STA

By Daniel D. Reno, Director, Technical Marketing, Western Digital and Member-at-Large, STA Board of Director

Enterprise customers demand the highest levels of quality and reliability for the systems they deploy. To deliver these robust solutions, industry leaders rely on the most advanced technologies available as a foundation of their product solutions. Within these products, the SAS (Serial Attached SCSI) interface has become a critical component for building the 'Unstoppable Datacenter'.

Author: Jeremiah Tussey, PMC Senior Applications Engineer

Today's challenging datacenter environments demand flexible switching and connection capabilities for storage scalability. SAS storage architectures allow for extensible configurations by providing incremental connectivity solutions: passive copper cables, active copper cables, and active optical cables. The fundamental basis driving these solutions is the necessity for a variety of cabling options; depending on a SAS topology's needs for tiered interconnectivity, segregation, and failover capabilities. Figure 1 shows these different available options and how they might be used.

It's nothing new that technology changes rapidly. Enterprise storage is no exception. Keeping data moving at faster speeds and having the ability to properly manage that data has never been more critical to having businesses run smoothly. Applications such as database, commerce and transaction, web serving and streaming use massive amounts of data and storage requirements continue to increase. New technologies need to be integrated into these storage architectures to reduce potential bottlenecks.

Author: Mike Karp, VP and Principal Analyst
Ptak, Noel and Associates

SCSI devices — first parallel and now, SAS — provide the lion's share of enterprise storage devices, and it seems likely that this leadership role will continue well into the foreseeable future. This is because as demands for better performance, configuration flexibility and manageability have increased over time, the SAS standard and the products that support it have also evolved. Second-generation SAS products are well established in the marketplace today, and progress continues with the design of a third-generation product set, which will begin to roll out in 2012.

Because first-generation SAS operated at 3Gb per second, second-generation operates at 6Gb per second, and the next generation will operate at 12Gb per second, most end-users continue to think of each generation in terms of its bus speed. Bus bandwidth provides a handy and descriptive shorthand, but there is much more going on than faster I/O.

SAS/SATA Compatibility. It's been a goal of the Serial Attached SCSI (SAS) technology since its inception. Originally this meant that a Serial ATA (SATA) drive could be plugged into a SAS port and work well. But that was back in the 3Gb/s SAS days.

Author: Harry Mason, President, SCSI Trade Association
Director of Industry Marketing, LSI Corp.

SSDs are low-latency storage devices that are finding their way into workstations, servers, and networked storage devices. Many of the uses for these devices are found in system-level caching environments, however recent cost improvements have made SSDs attractive for accelerating applications such as database searches.

SCSI Trade Association October 2009

Q1. What is the Advanced Connectivity Roadmap?

A1. The Advanced Connectivity roadmap is the STA connectivity roadmap to guide the industry through future SAS storage solutions. It specifies the Mini-SAS High Density (HD) (SFF- 8643/8644) connector as the converged connectivity scheme for SAS-based deployments. In addition, it defines SAS Connectivity Management for simplifying cable and connectivity management.

Q2. Name the factors that stimulated provision of the Advanced SAS Connectivity Roadmap.

A2. Factors which drove development and provision of the Advanced SAS Connectivity Roadmap include simplification of cable and connector options and the provision of managed connectivity standards. Additional factors include providing high-density connectivity and the extension of active copper cable to 20m and optical cable to 100m.

Author: Cameron Brett, Manager, Product Marketing, Enterprise and Storage Division, PMC-Sierra
With Contributions by Harry Mason, Director Industry Marketing, LSI Corp.

Not standing still, 6Gb/s continues to innovate with the SAS Advanced Connectivity Roadmap. The industry is trending toward large-scale SAS deployments with thousands of drives, multiple levels of SAS expanders, centralized SAS switches (all incorporating fail-over clustering), server virtualization and bladed processor complexes. This expansion is beginning to tax the basic SAS cabling and connector constructs that have been prevalent over the first two SAS generations.

The market is constantly demanding much more from the SAS interconnect to service increasingly more complex storage systems. The need to manage these large topologies becomes critical as does the greater need for substantially longer cabling distances.

Authors: Jay Neer, Advanced Technical Marketing Manager, Industry Standards, Molex
With Contributions by Harry Mason, Director, Industry Marketing, LSI Corp. and
Susan Bobholz, Product Marketing Manager, Intel

Introduction

The first article in this series of three articles discusses SAS connectivity and introduced the basic concepts of how SAS devices connect together as well as how SATA devices connect into a SAS infrastructure. The second article discussed how SAS connectivity has evolved over time. This third and final article in the series provides a review of the connectors and cable assemblies released for each revision level of the SAS standard.

SAS has experienced very fast growth based on the enhancements described in the previous articles. These expanded opportunities have created a need for the standardization of new connectors on several occasions. This article will show the chronology of these changes, by the SAS standard revision level, to provide an understanding of why convergence is important for revision SAS 3.0. Graphics are included for each of the revision levels to provide a visual connection to the product requirements as defined on the Advanced Connectivity Roadmap. The need for connector convergence in revision 3.0 becomes apparent and appropriate as the article unfolds.

Please read all three articles to understand the complete SAS connectivity story.

Author: Greg Schulz, Founder
StorageIO Group

Serial Attached SCSI (SAS) as a technology, has several meanings similar to the acronym SAS in general, which for IT professionals also refers to the Statistical Analysis Software from the SAS Institute. There is a linkage between SAS as a software package and SAS as a storage technology, particularly for performance and capacity-planning analysts that forecast storage usage and performance. However for now, let's focus on SAS as a storage interface technology, leaving the discussion about performance and capacity planning for another time.

Authors: Harry Mason, President of STA and Alice Tate, STA Marketing Manager

Special thanks to John Lohmeyer, Chair of the T10 Committee and Marty Czekalski, Vice President of STA, for their contributions

T10 is a Technical Committee of the InterNational Committee on Information Technology Standards (INCITS, pronounced "insights") and develops standards so that features and benefits can be implemented in commercial products in a common, compatible manner. INCITS is accredited by, and operates under rules that are approved by, the American National Standards Institute (ANSI). These rules are designed to ensure that voluntary standards are developed through the consensus of industry groups. Serial Attached SCSI (SAS) becomes a standard through the work, commitment and dedication of the T10 Committee members.

STA and T10
The SCSI Trade Association (STA) is not responsible for the technical standards concerning the SAS specifications. However, STA and the T10 Committee have a close working relationship. STA and T10 meetings are co-located to enhance the communications between, and the cooperation of, the two organizations. STA focuses on identifying SAS' marketing requirements and provides the forum to reach a consensus on features and benefits found on the roadmap. STA's primary mission is to promote the understanding and use of SAS technology. To that end, we are writing this article to further the industry's understanding of how SAS becomes a standard.

Defined Procedures and Policies
The T10 Committee has a clear set of procedures that guide the emergence of new standards. STA has developed a roadmap that maps SAS technology through 2015, however it is incumbent on the T10 Committee to propose new projects for each new SAS generation, and then develop a set of standard documents which support each generation.

Author: Mark Peters, Storage Systems Analyst, and Tony Palmer, Lab Engineer
Enterprise Strategy Group

Introduction
The relative success of new technologies is not a one-way street. Indeed, the history of IT is littered with great developments that never 'made it', storage technologies that have had more written about them than on them. 6Gb/s SAS products look great, and full of value, but will the enthusiasm of its promoters be matched by an eagerness to invest from its potential users? With the 6GB/s products rolling out now and over the coming months, there are many Enterprise buyers trying to figure out if, and how far, to jump into SAS. ESG has looked at this from both sides - the technical suitability as well as the adoption logic - and expects that SAS will indeed find success in Enterprise environments.

This article is not intended to repeat in any detail all the well-known attributes of SAS. Yes, it offers a number of benefits compared to traditional parallel SCSI technology including the use of thinner cables, the ability to transfer data over longer distances, providing faster data transfer rates, and the ability to create storage area networks; new and improved capabilities in terms of scalability, performance, capacity, zoning, multiplexing, security and so on, all look great on paper...but is SAS appropriate for and ready for the Enterprise? And is the Enterprise ready for SAS?

Authors: Paul Vogt, Senior Director of Product Management
               Dale Lafferty, Director of Alliances and Partnerships
               Xyratex International

Introduction
There is a technology shift taking place in enterprise storage environments that could help IT departments address some of the constraints the economy is placing on their budgets. The venerable Fibre Channel (FC) drives have been a staple in the enterprise for over a decade and their replacement by SAS drives is now in full force. Virtually all large storage system market leaders now offer enclosures with Serial Attached SCSI (SAS) disk drives in lieu of FC. While this may be good news for departmental budgets, how will the IT decision-maker feel comfortable with the long term reliability of SAS drives? There is good news about enterprise drive technology; SAS drives are enterprise proven. Market analyst firm, IDC, projects that SAS and SATA drives will replace FC drives in enterprise storage over the next five years.¹

(1) IDC: Worldwide Hard Disk Drive 2009-2013 Forecast and Analysis: A Post Crisis Fundamental Shift, May 2009, Doc # 218262

Author: Tonya Comer, Product Marketing Manager
HP

Serial Attached SCSI (SAS) incorporates differential signaling, which reduces the effects of capacitance, inductance, and noise experienced by parallel SCSI at higher speeds. SAS links are full duplex (Figure 1); they send and receive information simultaneously, thereby reducing a major source of latency inherent in parallel SCSI. Unlike traditional parallel SCSI that shares the bandwidth of one bus with many devices, SAS is a point-to-point technology that provides maximum bandwidth to each device, greatly improving scalability and performance. All end devices (initiators and targets) have a connection point called a port. Expanders and HBAs have multiple ports. A port can contain one or more transceiver mechanisms, or phys. A narrow port has only one phy, while a wide port has more than one phy.

Author: Anil Vasudeva, President and Chief Analyst
IMEX Research

Industry Trends

Explosion in the growth of Storage Data
The internet has been the catalyst behind the explosive growth of digital information, growing at an annual rate of 60% and estimated to reach 1,800 Exabytes by 2011. Regardless of the state of the economy, the amount of data that needs to be stored, accessed and managed will continue to grow exponentially, especially as new types of data such as that from social networking and internet video continues to mushroom.

Author: Greg Schulz, Founder,
StorageIO

Introduction
To say that "green" is a popular trend is an understatement. Green messaging in general and the information technology (IT) industry in particular tend to center around carbon footprint and emissions reduction or cost savings. Green is also being seen or talked about as being dead or falling off in importance and relevance.

While green hype and "green washing" may be falling out of favor or appearing on an endangered species list, addressing core IT data center issues that affect how resources are used to deliver information services is gaining attention. In an energy-efficient, environmentally and economically friendly manner, the industry is boosting efficiency and productivity and the trend is here to stay.

Author: John Rydning, Research Director, Hard Disk Drives
IDC

Storage device options continue to broaden for disk storage system OEMs and end users. For enterprise applications, hard-disk drives (HDDs) are now available in several form factors, configured with parallel SCSI, Fibre Channel, Serial ATA (SATA) or Serial Attached SCSI (SAS) interfaces. An increasing number of solid state drives (SSDs) are now also shipping for enterprise applications. DRAM-based SSDs have for many years satisfied the needs of very high performance, latency-sensitive environments, but at a high cost. Now, with the price decline in NAND flash and advances in technology, NAND-based SSDs have a growing opportunity in the datacenter. Similar to HDDs, flash-based SSDs are offered with several interface options.

Today's diversity of storage device options for the datacenter contrasts sharply with the limited selection available just five years ago. Consider the changes that have taken place just with hard disk drives. In 2003, essentially two HDD form factors serviced the large percentage of enterprise datacenter storage demands: 3.5 inch 10,000 rpm and 3.5 inch 15,000 rpm HDDs. Today, in addition to these 3.5 inch enterprise class products, the HDD industry also ships 2.5 inch 10,000 and 15,000 rpm enterprise-class small-form-factor (SFF) drives. Collectively, IDC classifies these drives as performance-optimized HDDs. By 2009, 2.5 inch performance-optimized HDDs will out-ship 3.5 inch products.

Author: Alvin Ooi, Marketing Manager,
Advanced Industrial Computer

The fast-growing demands of media storage in the broadcasting industry pose a significant challenge to the industry's IT professionals. The entire workflow process, from intake and production to play-to-air, requires massive storage capacities which are easily and quickly accessible. Streamlining the process of retrieving and restoring media, while maintaining IT overhead, is a key issue for industry broadcast media professionals. Their challenge is to find a large capacity, scalable solution that is fast, reliable and cost-effective.

Figure 1: The KCET-TV computer Room

KCET-TV serves Southern and Central California. It is watched by four million viewers a month in 11 counties, the largest broadcast reach of any public television station in the United States. Throughout its more than 40-year history, KCET-TV has won awards for its public affairs programming, drama and documentary productions, family and children's programs, community services and local and regional news.

Author: Steve Denegri, Storage Consultant, Financial Analyst

A study on data center electricity usage published a year ago by the Environmental Protection Agency (EPA) continues to receive attention in the storage industry. The study illustrates that storage is not keeping pace with servers and networking equipment as it relates to the amount of energy each of these hardware categories uses in the data center. In fact, the EPA study shows that storage is consuming an increasing portion of the data center's power budget as networking equipment and servers are maintaining a steady appetite for electricity, not a good trend in these times of skyrocketing utility costs. No wonder the EPA study recommends that the storage industry dramatically improve upon its power management semantics for disk and tape systems. And the industry pundits are taking this data and running with it, with talk of underutilized storage resources and customers not getting the most of the equipment they've purchased, as if that's a new theme. Regardless, many vendors in the storage industry are salivating at the thought of bringing new energy-efficient products to market, believing that this problem has all the ingredients of a paradigm shift that could rearrange the competitive playing field.

However, these vendors would be better off recognizing that this heightened attention to energy efficiency is less indicative of a new growth opportunity and, more likely, portends an uncertain future for the industry, as a whole. Countless industries have reached an energy ceiling over the past half century, only to realize, soon after, that revenue potential had peaked. What follows is a survival contest that only Darwin would love: more combinations at the top of the food chain and significant consolidation or closed doors among the multitude of suppliers. As revenue potential falls, those who are fortunate enough to survive must remain in cost-cutting mode in order to stay competitive.

Author: Mike Karp, Senior Analyst,
Enterprise Management Associates

"Storage density" is the term that describes how much storage capacity can be packed into a specified amount of space. The actual measurement varies a bit depending on your focus. Disk drive vendors measure bits per square inch, while tape vendors think in terms of bits per linear inch. Data center managers measure things at a more macro level: for them storage density is a measure of terabytes (and increasingly, petabytes) per square foot of floor space.

At least that's the way things were measured up until recently.

Author: Ashish Nadkarni, Principal Consultant
GlassHouse Technologies

Flash drives, also known as solid state drives, have a promising future in the enterprise space. They promise to overcome literally all limitations of traditional hard drives - power consumption, heat dissipation, mean time between failures, speed and IO/s, etc. The list is long. There is no doubt that eventually they will replace all rotational hard drives in the enterprise space, as well as the consumer market. If you have bought into the promise of solid state drives and are planning to invest in it right away, hold your plans for now. The technology should be continually researched to figure out how to best help your environment, stopping short of actually buying anything - yet. The technology is seemingly mature but still has to establish itself in the enterprise space. Then, and only then, will it become viable as a replacement technology for spindle-based drives.

< Author: Bob Griswold, Senior Technical Program Manager Lead, Core Operating System Division, Storage Platform,
Microsoft

Finally, the most pervasive enterprise technology has come to a crossroads. Parallel SCSI was the heart of the datacenter – used as the standard hard drive connection and communication scheme for server and storage environments. Companies have been developing and utilizing SCSI for over 20 years as the mainstay for enterprise storage, but the technology is now transitioning to Serial Attached SCSI (SAS).

In the enterprise, where Microsoft has its biggest growth opportunities, SAS has crossed over to being pervasive in the industry. This is a trajectory point where SAS is now taking over from parallel SCSI. So any question that any of your customers may have as to what technology they should choose for direct-attached storage in order to be able to use it with Windows in their enterprise, SAS is obviously the clear choice. SAS builds on 25-plus years of SCSI industry influence and growth, and is the logical next choice for most customers.

Author: Marty Czekalski, Vice President, SCSI Trade Association
Interface and Emerging Architecture Program Manager, Seagate

At the recent SCSI Trade Association (STA) SAS Solutions Open House in San Jose, Marty Czekalski discussed the past, present, and future of SAS. He went through the SAS roadmap, briefly describing 3Gb/s SAS origins, 6Gb/s SAS highlights, planned enhancements to 6Gb/s SAS, and the outlook for 12Gb/s SAS. In addition, he discussed the capabilities these technologies enable in delivering solutions to end customers.

The first SAS Plugfest was in 2004, when industry participants worked together to ready 3Gb/s SAS products for the market. The initial SAS releases focused on preserving the legacy SCSI infrastructure and enabling SATA in the environment. Since then, 3Gb/s SAS products have become widely accepted. Now, the storage industry is moving forward and getting ready to bring out a major upgrade from 3Gb/s SAS to 6Gb/s SAS. The first official 6Gb/s SAS Plugfest will be held at the end of this year. However, at the SAS Open House, 6Gb/s prototype hardware is being demonstrated by several industry providers working together. 6Gb/s SAS, with backward compatibility for 3Gb/s, will quickly become a key interface in the storage world. But even as 6Gb/s SAS is getting ready to be introduced to the market, plans are being formulated for 12Gb/s SAS in the late 2012 timeframe.

Author: Todd Mottershead, Manager, ProLiant Server Development
HP

With virtually every IT department in today's corporate world facing growing user demands and shrinking budgets, storage vendors are rushing to deliver the cost efficiency of low-end systems with value-added features and availability levels typically found only in enterprise class facilities. This focused effort began back in 2005 when companies like HP were faced with technical hurdles ranging from drive density limitation (approximately 300 GB) to storage interface challenges (Ultra 320 was running out of steam), to seemingly simple issues like bulky parallel SCSI cables, not to mention the demands of the customer.

Author: Jesse Molina, Product Marketing Manager,
PMC-Sierra

The transition from Parallel SCSI to Serial Attached SCSI (SAS) has been taking place for more than three years, since the first SAS hard disk drives (HDDs) were introduced to the market in 2005. Since then, SAS has made its way into a number of applications: from high performance workstations, to Small and Medium Business (SMB), external storage Just a Bunch of Disks (JBODs) and enterprise-class servers. SAS performance, matched with its support for Serial Advanced Technology Attachment (SATA), has made the transition to SAS economical and ideal for addressing many storage applications using a single storage networking infrastructure.

SAS and SATA Compatibility
One of the main reasons that SAS has been able to scale is that it is designed to be compatible with SATA HDDs, which provide the highest capacity at the lowest cost-per-gigabyte of any storage media. In addition, the use of a SATA Active/Active port selector to dual-port a SATA HDD enables fully redundant storage architectures with greater system fault tolerance.

Author: Susan Bobholz, Storage Market Development Manager,
Intel

Does the storage industry really need another storage fabric? There have been heated debates over the use of Fibre Channel, iSCSI, even InfiniBand, as THE best fabric, that continues even today. Yet, as larger and larger SAS-based topologies are being implemented, there is discussion over using Serial Attached SCSI (SAS) as a fabric technology. To fully understand this phenomenon, it's important to understand the roots of SAS and how SAS systems are being architected.

SAS was developed as the natural evolution of parallel SCSI, enabling point-to-point drive connections via a serial interface. In its simplest form, one SAS port on a SAS Host Bus Adapter (HBA) connects to one drive. Because SAS drives can be dual-ported, a single SAS drive can connect to two SAS HBAs. This enables redundant systems to be built, such that if one SAS HBA failed, the data on the drive is still accessible via the second HBA.

This is an excellent model for storage inside a server, however in many instances, more storage is needed than will fit into the server chassis. To support direct-attached storage outside of the server, the concept of an expander was defined. SAS Expanders enable a simple switching topology. SAS expanders are often incorporated into SAS Just a Bunch of Disks (JBOD) boxes, enabling a single SAS connection from the server SAS HBA directly to the SAS JBOD. Additionally, SAS expanders allow multiple servers to connect to the same SAS JBOD, as shown in Figure 1. The SAS JBOD can then be shared between multiple servers.

Authors: Chris Hoffman, Senior Product Marketing Manager
Sam Sawyer, Director of Product Marketing Embedded Storage Products
Emulex Corporation

Introduction
Several years after its initial ratification, the Serial Attached SCSI (SAS) protocol has gained momentum and is now entering the advanced stages of replacing parallel SCSI for the purpose of connecting disk drives in server applications. The majority of drives now being used for these internal storage system applications are SAS interface drives.

Within external storage systems the story is different. Fibre Channel has been the dominant protocol for providing high performance back-end connectivity from the RAID controllers through the disk enclosures and ultimately, down to the disk drives. Now with the success and efficient high-volume production of SAS drives used as internal storage for servers, the general competitiveness and even long-term availability of Fibre Channel disk drives has become uncertain. In response, storage system suppliers are rethinking the design of their external storage systems to incorporate SAS as a back-end protocol with the goal of deploying SAS drives. Like Fibre Channel, a SAS infrastructure can support the attachment of SATA drives, providing both high-performance and low-cost storage alternatives.

This article explores three alternatives for connecting high capacity, low-cost disk drives into external storage system designs utilizing the SAS protocol.

Author: Sam Barnett, Business Manager, Serial Attached SCSI and Serial ATA Storage / Storage Networking Products, Storage Products Group, Maxim Integrated Products

As first generation systems based on Serial Attached SCSI (SAS) technology enter the market, leading server and storage OEMs are racing to deliver the next group of platforms based on an ever-evolving technology landscape. Unlike other semiconductor vendors, Maxim opted to enhance its popular NexSAS™ product family concurrently with the release of generation I systems. This leapfrogging approach to the deployment of SAS technology has led to the introduction of many new products with features found only in high availability, superior performing Fibre Channel systems today. Comprised of three new high-phy-count expanders, extensions in intelligent mux/de-mux devices, a new enclosure management/SAS backplane controller, and the industry's best rate, agile signal conditioners, the NexSAS™ line delivers on the promise of high performance storage solutions for SMB (small/medium business) as well as enterprise systems.

The Maxim NexSAS™ product family is divided into four functional areas: expander technology, SAS/Serial ATA (SATA) support devices, server/enclosure/baseboard management, and signal conditioning. This article explores Generation 1.5 NexSAS™ expander technology in detail.

Author: Chaz Nichols, Global Channel Marketing and Kent Bransford, Sr. Technical Editor,
Seagate Technology

"Use the right tool for the job" is a time-honored maxim that's particularly relevant to developers and system builders seeking to deliver maximum value to their customers. Data center storage requirements continue to expand and diversify, challenging IT professionals to move beyond the traditional "speed or capacity" dichotomy to also address such issues as power consumption, system cooling, data center footprint, ease of data migration and more.

Efficiently meeting such a broad spectrum of storage requirements with only a narrow range of hard disk drives (HDDs) from which to choose is simply not possible...a fact to which many storage professionals can ruefully attest. In response to this dilemma, Seagate has recently made four compelling additions to its comprehensive Savvio, Cheetah and Barracuda ES enterprise disk drive families.

Storage solutions play a fundamental role in shaping data center footprint, power and cooling profiles, and Seagate has purpose-built its new Savvio 15K, Cheetah 15K.6, Cheetah NAS and Barracuda ES.2 Serial Attached SCSI (SAS) disk drives to maximize data center ROI. By combining superior performance and capacity with significantly reduced space and energy requirements, Seagate HDDs enable you to build higher performing, greener and more eco-friendly systems.

Author: David So, Product Marketing Manager and Bruce Grieshaber, Product Manager
LSI

Over the past several years, the SCSI Trade Association (STA) has gone to great lengths to educate the public on the features and benefits of Serial Attached SCSI (SAS). STA has even sponsored a series of plugfests at the University of New Hampshire's InterOperability Lab to ensure the compatibility of different vendors' SAS products with one another, thereby easing the adoption and integration of SAS into the marketplace. The result is that SAS has indisputably been accepted as the Direct Attached Storage (DAS) interconnect of choice. Since SAS' inception, the storage industry has announced a wide array of SAS infrastructure components as well as SAS-based servers and external storage systems. Today, most server platforms use SAS for the internal drive interconnect. And with the ability to support SAS and Serial ATA (SATA) hard drives, it is quickly becoming the mainstream disk drive interface for external storage enclosures.

Author: Matthew Hallberg, Storage Protocol Specialist
LeCroy Protocol Solutions Group

In today's rapidly changing, data-centric environment, one key requirement remains constant: every company needs reliable and fast access to critical business information. A company's fortunes are based on time-to-market in product development, the breadth and reliability of their product line, the availability of critical product design, sales and support information, and the access speed with which this information can be obtained. In recent years, the storage infrastructures of data centers have evolved with the introduction of Serial Attached SCSI (SAS) and Serial ATA (SATA). These key infrastructure changes have resulted in better performance, better availability, and lower cost.

These improvements don't stop there, as the SAS/SATA environment is undergoing yet another revolution with the introduction of the new SAS-2 specification. One of the major changes in SAS is the doubling of the basic data rate from a previous maximum of 3.0 Gb/s per link to a new standard of 6.0 Gb/s per link. Additionally, there are some new support features in SAS-2 that are designed to be highly beneficial to data centers.

Figure 1: Two examples of Test Emulation

Author: Don Jeanette, Sr. Manager, Product Marketing
Fujitsu Computer Products of America

When computers use less energy, they cost less to operate, thereby increasing a company's profits. It does not get any simpler than that. Fujitsu has once again answered the call to helping companies save money by saving power, while at the same time, helping the environment. Fujitsu is now shipping its third generation 2.5" 10K RPM and first generation 15K RPM Enterprise hard disk drives. These drives range from 36GB up to 147GB in capacity.

While today's computers offer higher processor speeds and more memory at a lower acquisition cost than ever before, they cost much more to operate. That's because while newer server-class computers are smaller and more powerful than before, their greater processing power and increased capacity for storage make them consume more power as they perform their work.

These increasingly powerful processors, larger-scale memory devices, emit more waste heat than earlier models. They have less space in which to dissipate heat, and that heat must dissipate through higher-volume fans. Furthermore, the additional heat dissipated into data centers has to be re-dissipated using more powerful air-cooling systems.

Author: Jim Pascoe, Corporate Communications
Hitachi Global Storage Technologies

The U.S. Environmental Protection Agency (EPA) recently issued a report on energy efficiency in data centers and the results were staggering. According to the EPA, energy usage at data centers doubled between 2000 and 2006, and it's poised to double again by 2011. Space, system cost and low power considerations in data centers are of primary importance to IT executives in the next few years.

In response to these trends, many data center managers have begun transitioning to small form factor enterprise hard drives for use in their server and storage applications. These 2.5-inch 10K RPM enterprise-class hard drives have been designed to deliver increased performance, improved server/storage density, greater thermal efficiency and lower total cost of ownership for enterprise computing.

Author: Alvin Ooi, Marketing Manager,
AIC/Xtore

Since the market emergence of Serial Attached SCSI two years ago, many high-end storage solution providers and OEMs have recognized the advantages of SAS over its parallel predecessor. Vertical markets that have since adopted SAS technology are the entertainment industry, medical imaging, financial institutions and research and government institutions, which typically need performance and/or capacity. SAS can offer good value, performance, and scalability.

SAS Advantages

In general, everyone recognizes the following advantages SAS offers:

• Superior aggregated performance over 4-lane wide ports -- providing throughput of up to 12Gb/s SAS
• Dual-ported design with fail-over capabilities
• Support for both SAS and Serial ATA (SATA) HDD in a single enclosure to eliminate redundant qualification and certification efforts, as well as the ability to achieve cost-effective storage
• Available edge and fan-out expander technologies for easier expansion and unmatched scalability
• Longer interconnect distance allowed compared to SATA for low-cost expansion enclosure solutions

Although overall market share is still relatively small compared to SATA, parallel SCSI and even Fiber-Channel, the majority of the next generation solutions currently being designed by OEMs are based on SAS technology. But demand for SAS is high and increasing.

Author: Levi Norman, ISS Storage Strategist, Industry Standard Servers
HP

From the time SAS was envisioned to this point, we have heard time and again it is to be much more than parallel SCSI ever hoped to be. It should deliver unsurpassed ROI, new and unique configurations and unparalleled performance gains, etc. It actually began as an engineering dilemma of how to overcome the issue of speeding up the bus and keeping all the data synchronized, on path, and ready to arrive at its destination in a timely and safe manner. pSCSI could no longer guarantee the safety or even the timely arrival of the 'payload,' thus the look elsewhere for a competent answer.

The idea of serial technology has been around for quite some time in varying forms and formats, alongside varying speeds and levels of security and connectivity. But the idea of using it cost-effectively outside of the Fibre Channel world with a cost-effective connection, (although smaller, stronger connectors, thanks to IB and ATA), had only recently been thought of. Long story short, SAS was born. It was born with 3Gb speeds, it was born with great expandability above and beyond pSCSI, and it is born with better inherent management than pSCSI.

ROI on a data center is easily calculated, right? Yes, if you are starting from the ground up. What about those folks that have a datacenter today? What do they do? How do they realize an immediate benefit? How do they calculate it? First, SAS is inherently SCSI and inherently connects into the architecture, yet immediately has architectural and performance benefits. The drives became more robust as they became smaller, point-to-point architectures sped up the transactions, and scalability went up nearly tenfold. Results get better immediately for even the existing datacenter. And secondly, HP as a company, offers a host of methods to measure performance and transactions with a variety of tools and industry monitored tests.

Authors:
Chris Hoffman, Senior Product Marketing Manager
           Michelle Ng, Director of Product Marketing
           Emulex Embedded Storage Products

Introduction
Serial Attached SCSI (SAS) has been making in-roads into the server storage market for the last year — which is all part of the natural evolution for storage since SAS was designed as the replacement technology for SCSI. However, now, as we are seeing SAS deployments begin to advance into external storage systems, it becomes much more important for storage system providers to consider the full cost of ownership for the products they are deploying. Not only is the on-going cost of goods an important factor to consider, but ease of deployment, and overall flexibility in system design are other factors that should be kept in mind.

This article discusses two new SAS-based products – the Emulex IOP 502M and the Emulex IOC 500S — and how they can make storage system providers jobs easier by enabling multi-application designs for next-generation external storage arrays.

Author: Greg Meythaler, Product Marketing Engineer
Intel

We've all heard the mind-boggling statistics. Data is accumulating at a phenomenal rate, more than doubling every two years. And analysts estimate that even though a whopping 161 exabytes of digital information was created worldwide in 2006, we can expect to generate more than six times that amount - 988 exabytes - in 2010.

Resellers, take note: Digital data growth represents a golden selling opportunity, especially if you can tap into the small-medium business (SMB) segment. Most of these businesses don't have a storage strategy to begin with, let alone a plan for growth. Yet with so much data on the horizon, they will be forced to do something about storage very soon. It's an opportunity you really can't afford to ignore.

But it's a challenging one too. SMBs need storage that can quickly and easily grow with their business and their data. They want the flexibility to go with a DAS strategy one day, and then migrate to NAS or SAN as their needs change. Integration with existing networking equipment is important. Solutions must be powerful and - above all - reliable.

Author: Cameron T Brett, Manager, Product Marketing
Enterprise and Storage Division,
PMC-Sierra

Serial Attached SCSI (SAS) is now a mainstream technology for enterprise servers and storage. Evolving from parallel SCSI to a serial technology, SAS is much more capable than its parallel predecessor. SAS provides a roadmap to faster speeds and can create, and be managed as a fabric with the use of controllers, expanders and muxes. The standard today is 3Gb/s (300MB/s) across a SAS link. 6Gb/s SAS is coming and PMC-Sierra, an established storage technology provider of SAS, SATA and Fibre Channel solutions, is leading the way.

Author: Thomas M. Coughlin, President,
Coughlin Associates

With entertainment and media content increasing in resolution, content data files have swelled and data throughput has increased proportionally. At the same time content producers are under more pressure to control prices than ever before. Serial Attached SCSI (SAS)-based storage systems play a big role in making these seemingly contrary goals possible.

Digital Production Means Lots of Bytes
The introduction of digital production technology is a great enabler of professional creativity. It encourages new levels of realism and special effects in the content and increases the efficiency of production at the same time as it decreases the costs of production. Because of the ease of digital capture of video content, producers now shoot a lot more hours before editing. This results in many more hours of content than was the case for film capture, similar to the trend seen with the conversion from film to digital still photography.

Generally, digital content producers shoot 10X more hours of content than was typical with film production. Digital production has resulted in more content, and increasingly more content is kept on associated post-production storage systems. Furthermore this digital content is kept on-line for a longer period of time. Some facilities even use disk arrays for active archives.

Author: Russ Fellows, Analyst
Evaluator Group

Why Consider SAS?

Serial Attached SCSI (SAS) is both a storage interface to disk and tape drives, as well as a storage connectivity technology. As the natural evolution of the older parallel Small Computer System Interface (SCSI) technology to modern technology, SAS provides application and device driver investment protection. It also provides investment protection by providing system architects another alternative for midrange storage networks while supporting both SAS and SATA storage devices.

In many ways, SAS uses the best of existing disk and connectivity technologies, leveraging Advanced Technology Attachment (ATA), SCSI and Fibre Channel (FC) technology. SAS is a continuation of the highly successful SCSI protocol, updated with current serial-attached connectivity technology. Additionally, SAS connectivity supports both high-performance SAS drives and high-capacity Serial ATA (SATA) drives simultaneously. SAS connectivity, along with SAS and SATA drive choices, provides users with the ability to mix and match drive types to best meet their business application requirements. These factors all serve to provide investment protection with past storage protocols while utilizing current technologies when choosing SAS technologies.

By David G. Hill, Principal,
Mesabi Group LLC

Blade servers are now very familiar to IT organizations, but they still have a lot of growth potential. And one of the gating factors for unlocking that potential is improving the relationship of blade servers with storage. Blade servers need a close relationship with storage — just not too close. In order to get the most out of blade servers, no storage should be on the blade server itself. The storage should be either on a local "network" within a chassis (i.e., direct attached storage (DAS)) or externally on a storage area network (SAN). Why?

Take the case where a blade has its own hard disk drive (HDD) for application data. Two problems arise; one with provisioning and one with data protection. Provisioning is a capacity planning issue. What happens if the disk fills up? Neither adding another disk nor migrating to another server with more storage is a palatable solution. Data protection is about the fact that the disk is a single point of failure. For data protection purposes, the disk should be mirrored. But who wants to put two hard disks on the same server blade for cost, blade real estate, and energy budget reasons? Using storage on the blade itself for application data is not a good idea.

Author: Dan Tanner, Founder and Principal
ProgresSmart

"Feeds and speeds" matter to engineers and are quoted by shallow analysts. Price matters to the business buyer, but only in the context of effectiveness. This brief article explains why you should care about Serial Attached SCSI (SAS).

SCSI (pronounced "skuzzy"), is the acronym for Small Computer System Interface. SCSI is a standard that had been around for years, widely used in high-performance workstations and servers. But until recently, SCSI cabling and electrical interface employed cumbersome and limiting wide parallel ribbon cables and wide connectors. Making the SCSI electrical and physical cable/connecters into slim serial parts has removed complex speed to precise cabling matching requirements and eliminated the severe configuration restrictions that had plagued parallel SCSI and which had forced the invention and employment of Fibre Channel (FC) or even Internet SCSI (iSCSI). In the bargain, SAS saves on both space and, importantly, uses far less power.

Author: Alvin Ooi, Marketing Manager
Xtore Extreme Storage
Advanced Industrial Computer

Introduction
While High Definition (HD) video contents are getting more and more popular in real video production, TV companies are experiencing the bottleneck of using legacy equipment to edit their HD video programs. One of the customers of PFU Systems (Panasonic, Fujitsu and Uchida), GCTV (Green City Cable TV), a local cable Nagoya TV Station in Japan, needed a cost-effective storage solution that provided high performance for editing multiple HD quality video. The traditional SCSI (Small Computer System Interface) Ultra320 SCSI-based storage system cannot work smoothly with a nonlinear video editing system. When GCTV used an Ultra320 SCSI RAID System to edit multiple HD video chips, they could only run three restricted HD video streams (draft quality) at the same time without frame skips. Since the HD video format is 1080i with a 145Mb/sec data rate, a Fibre Channel solution is able to resolve the performance bottleneck. However, it is very costly to acquire a FC solution. Serial Attached SCSI (SAS) is capable of providing equivalent performance at a lower price point.

Author; Kent Smith, Product Manager,
LSI Corporation

Exponentially increasing storage requirements in data centers, combined with the implications of regulations such as Sarbanes Oxley and HIPAA, entails large amounts of "business-important" information that must be periodically backed up and accessed while remaining readily available. IT managers are under extreme pressure to find storage solutions that deliver more capacity for less money – without sacrificing reliability or data availability.

In order to address this requirement, nearline enterprise disk array systems are emerging that retain the Fibre Channel (FC) infrastructure on the front-end of the array (in order to fit into existing SANs), while using a mix of Serial Attached SCSI (SAS) and Serial ATA (SATA) drives instead of more expensive FC drives. Such mixed-technology systems reduce costs while retaining the availability, manageability, data integrity and functionality achieved with FC-based storage systems. Though SATA-based storage solutions are ideally suited for the specific workload, capacity, and cost requirements of "secondary storage", SAS-based storage solutions provide performance and reliability comparable to current FC storage solutions.

Author: Suresh Panikar, Director, Branded Products Marketing
Adaptec

One of the most important factors in the growth of Serial Attached SCSI (SAS) is its seamless compatibility with Serial ATA (SATA) storage devices. Until the introduction of SAS, choosing a storage infrastructure meant making a choice to which a business would be committed throughout the long life of the infrastructure. This choice usually reflected a compromise between actual storage needs and budgetary considerations, yet it drove the future of the company's storage infrastructure. Because moving away from the initial decision as needs changed or storage technology evolved always required a tedious and costly upgrade, many companies have clung to an outdated solution that no longer makes sense for their business.

The SAS/SATA compatibility built into SAS components eliminates this long-term commitment to a single storage solution and allows the creation of solutions that can adapt to changing needs with a minimum of cost and complexity. This provides advantages for both end-users and the solutions providers on whom they depend.

Author: Daniel D. Reno, Senior Strategist, Marketing and Strategy, Enterprise HDDs
Hitachi Global Storage Technologies

As noted by Gartner Group in the recent SCSI Trade Association (STA) press release, Serial Attached SCSI (SAS) adoption rates experienced a significant increase in 2006, and SAS is expected to overtake Ultra320 SCSI, or Parallel SCSI, as the interface of choice for a variety of enterprise storage applications this year. Key drivers of SAS adoption have been reduced backplane complexity and improved signal integrity leading to greater reliability. In addition, the interface enables higher data transfer rates and improved scalability over Ultra320 SCSI.

SAS interface compatibility with Serial ATA (SATA) hard drives has been an added benefit, driving overall adoption rates, particularly with the explosion (since 2005) of SATA hard drive use for secondary storage. This ramp is expected to continue given that highest-capacity (one-terabyte) enterprise SATA hard drives recently began shipping in volume.

The combination of high-performance SAS hard drives and ultra high-capacity SATA drives gives builders of these mixed-interface systems and their customers the best of both worlds: tiered storage that is optimized for both performance and reliability, and cost and capacity.

Authors: Chaz Nichols, Global Channel Marketing and Kent Bransford, Sr. Technical Editor
Seagate Technology

"The only constant is change" is surely a familiar (and vexing) maxim to storage managers around the world. Grappling with this ever-present challenge requires a storage interface capable of both meeting today's requirements and seamlessly adapting as priorities inevitably evolve over time. Until recently, addressing an enterprise's broad range of storage needs required a combination of SCSI and Serial ATA (SATA) infrastructures, an inefficient and unwieldy approach.

But now the rules have changed, thanks to Serial Attached SCSI (SAS) and its compatibility with SATA. A key component of the SAS feature suite, this ground-breaking compatibility produces remarkable storage synergies and efficiencies, enabling IT professionals to achieve their performance and capacity objectives with a single SAS infrastructure.

The one-two punch of the SAS/SATA value proposition is simple: SAS hard disk drives (HDDs) deliver the speed, reliability and scalability demanded in high-availability enterprise environments, while high-capacity SATA drives are purpose-built for bulk storage applications, combining low cost per GB and greater reliability and scalability than their parallel ATA ancestors.

Author: Cameron T. Brett, Manager, Product Marketing
PMC-Sierra, Inc.

Serial Attached SCSI (SAS) was designed from the ground up for compatibility with Serial ATA (SATA) disk drives. The benefits of this compatibility include lower total cost of ownership (TCO), increased flexibility and usability, as well as allowing for larger storage capacities in enterprise and small business environments. To understand SAS and SATA compatibility, the enabling components are a good point of departure.

Author: Paul Vogt, Sr. Director, Product Management
Xyratex International, Ltd.

The Need for Serial Attached SCSI (SAS)
In order to understand the justification for the industry's investment in a new I/O technology standard, it is useful to look at a typical parallel Ultra320 SCSI bus configurations. This type of configuration was a common Direct Attached Storage (DAS) implementation in an enterprise server configuration in the early 2000's. Illustrated are two boot drives in the system as well as an additional Ultra320 SCSI JBOD (Just a Bunch of Disks) connected to the SCSI adapter in order to increase the capacity of the system.

Author: Susan Bobholz, Market Development Manager
Intel

Serial Attached SCSI (SAS) is the logical evolution of the traditional parallel SCSI interface, and it represents the continuation of more than 25 years of technology development and infrastructure investment. In SAS, the SCSI protocol is transported over a serial interface. Compared to the existing parallel SCSI interface, SAS enables faster device interconnect speeds, simpler cabling and improved system reliability, while preserving existing SCSI capabilities. SAS also improves connectivity to larger numbers of drives and also enables compatibility with Serial ATA (SATA) drives. The SAS interface standard was developed by the T10 Technical Committee of the International Committee for Information Technology Standards (INCITS). The latest specification "Serial Attached SCSI version 1.1" has been adopted by the American National Standards Institute (ANSI). A wide variety of SAS products has been shipping for several years including hard drives, controllers, servers and networked storage systems.

What is SAS?
SAS is the high-speed serial successor to Ultra320 SCSI as well as an I/O infrastructure that provides for a wide range of storage solutions. SAS goes beyond a mere disk drive interface; it provides a set of components that include connectors, cables, and expanders that can be used to deploy a large number of solutions into the storage and server market. While SAS preserves the traditional SCSI usage model, it widens the types of applications and markets it can serve including blade storage, tiered storage and near-line storage, and shared storage between hosts.

Author: Cameron T. Brett, Manager, Product Marketing
PMC-Sierra, Inc.

Putting Serial Attached SCSI (SAS) to work is relatively easy. Server and storage solutions can be created ranging from simple direct-attached storage (DAS) in servers to high-availability, switched rack environments. To look at these solutions, it is best to understand the SAS building blocks first.

Author: Kent Bransford, Senior Technical Editor,
Seagate Technology

The following is an actual case study, illustrating how SAS technology is a key enabler of high-performance business intelligence storage solutions that utilize the concept of a "server brick."

Microsoft Project REAL
The server brick concept was developed by Microsoft while working on Project REAL (Reference implementation, End-to-end, At scale, and Lots of users). The project involved a major US retailer with over 800 stores in the US and more than 40,000 employees. While the retailer's sales and data warehouse was initially 1.5TB in size, by the project's completion it had grown to over 4TB and was expected to continue this rapid expansion in the future.

Author: Stephen Weekley, Marcom Program Manager, Storage, Corporate Planning and Marketing, LSI Logic
With Tim Bolden, president of iGLASS Networks and Tomas Havrda, Managing Partner of Solid Access Technologies

Serial Attached SCSI (SAS) user sees dramatic productivity improvement by adopting the newly developed solid state disk (SSD) device from Solid Access Technologies with its breakthrough IOP performance/cost metric. iGLASS Networks selected the Solid Access Universal Solid State Disk 200 (USSD 200) along with LSI's Serial Attached SCSI (SAS) Host Bus Adapter (HBA) solution to achieve a remarkably fast storage system.

Author: Heidi Smith, Product Marketing
HP

SAS Infrastructure is the next generation of storage
Serial Attached SCSI (SAS) and Serial ATA (SATA) solutions are the next generation in storage technology, offering better performance, flexibility and scalability. Vendors are now offering a complete line of SAS capable products including small form factor (SFF) and 3.5" hard drives, a variety of controllers and HBAs, servers and storage enclosures, with more to come.

Why serial now? Parallel SCSI and parallel ATA have reached their technological limits. Parallel connectors are too big for new dense server and storage products and the cabling is limiting airflow. In addition, cross talk over the cables is making system design more complicated resulting in increased backplane and cabling costs. Electrical challenges are being encountered while attempting to increase parallel I/O speeds to accommodate HDD data rate increases. Serial Attached SCSI greatly helps to reduce these issues while providing customers unprecedented flexibility and scalability.

Author: Sam Barnett, Product Line Manager, Serial Attached SCSI and Serial ATA
Storage Products Division, Vitesse Semiconductor

Mention Serial Attached SCSI (SAS) technology to a gathering of IT professionals and the room is immediately charged with an air of excitement. Take the dialogue one step further and associate SAS with Fibre Channel front-ends/fabrics/switching or a Storage Area Network (SAN), and the mood turns somber – until economic reality sets in.

SAS technology offers a wealth of benefits to the enterprise server and enclosure customer (high reliability and performance, mixed enterprise/desktop drive support, improved economies of scale), but it was not developed with networking in mind. Even so, with modest extensions to the existing standard SAS could be positioned to dominate the changing storage network landscape.

This article explores SAS technology and its logical extrapolation as a viable protocol for the Storage Area Network (SAN) of tomorrow.

Authors: Bob Brencic, Senior Director of Product Marketing
              Michelle Ng, Director of Product Marketing
              Emulex Embedded Storage Products

Serial Attached SCSI's (SAS) use in disk drives and external storage systems is one of the hottest topics in the data storage industry today. Already gaining volume momentum in server-based applications as it replaces its SCSI technology predecessor, SAS is now starting to migrate into entry-level external storage systems as well. However, applying SAS to external storage systems presents a different set of challenges than those confronted within servers, because external storage system applications demand uncompromising performance and reliability. This article discusses how SAS will be deployed and used in external storage systems.

By Paul Vogt, Director of Product Marketing,
Adaptec

The flexibility of Serial Attached SCSI (SAS) allows it to be used as a universal connectivity standard for a wide range of business needs. In addition to its role as a replacement for parallel SCSI, SAS now offers the ability to reduce the cost of servers and storage networks, to create tiered solutions that weren't possible before, and to provide investment protection for SATA installations. While SAS performance and scalability generate a majority of the media attention, it could be the flexibility that SAS brings to storage subsystems that creates the most value for your business.

SAS as a parallel SCSI replacement
SAS maintains support for the proven SCSI command set while offering much better performance, scalability, and availability. Stability and reliability have made parallel SCSI the standard in storage connectivity for twenty five years. SAS offers compatibility with this command set while overcoming the physical limitations of parallel SCSI. Now with SAS, it is possible to take advantage of dual-port drives, redundant connections, failover support and scalability up to 128 attached devices and over 16,000 addressable devices. Performance at 3Gb/s per port can be aggregated into wide-port connection bandwidth.

Author: Kent Bransford, Senior Technical Editor,
Seagate Technology

As capacity demands and energy costs continue to escalate, the need for greater data center efficiency has become increasingly urgent. A recent study by research company, Robert Frances Group, found that 41 percent of IT executives surveyed at Fortune 500 companies view power and cooling as major concerns. That same study revealed that while Fortune 1000 companies averaged 138TB of storage in 2004, by 2006 that figure had mushroomed to 600TB.

Recognizing the fundamental role that hard disk drive (HDD) storage plays in shaping the data center footprint, power and cooling profiles, Seagate has specifically designed its Savvio and Cheetah enterprise-class SAS drives to deliver maximum performance while enabling systems with reduced space and energy requirements.

Author: David So, Strategic Marketing Manager,
LSI Logic

The storage industry has gradually been introduced to the newest storage interface, Serial Attached SCSI (SAS), over the past few years. In that time, numerous companies have announced a wide array of SAS infrastructure components as well as SAS-based servers and external storage systems. Among those companies are SCSI Trade Association (STA) members LSI Logic, Adaptec, Fujitsu, Hitachi GST, HP, Intel, Molex, PMC-Sierra, Seagate, and Vitesse, with products including ICs, host bus adapters (HBAs), cables, 2.5" and 3.5" disk drives and drive enclosures.

STA has gone to great lengths to educate the public on the features and benefits of SAS and why this technology will be critical to the future of Direct Attached Storage (DAS) environments, and potentially Storage Area Networks (SANs). STA has sponsored a series of plugfests at the University of New Hampshire's InterOperability Lab to ensure compatibility of different vendors' SAS products with one another, thereby easing the adoption and integration of SAS into the marketplace.

Author: Rachelle Trent, SAS Product Marketing Manager,
PMC-Sierra

PMC-Sierra's maxSAS™ storage family includes Serial Attached SCSI (SAS) expander switches with zoning support and intelligent Serial ATA (SATA) active/active multiplexers. It also includes SAS/SATA retimers and enclosure management processors supporting the 3.0 Gb/s SAS specification. To accelerate OEM and ODM development cycles for tiered-storage disk arrays, PMC-Sierra provides complete reference systems for its entire maxSAS product line.

PMC's maxSAS products are all production released and shipping in volume, as follows:

PM8398 SXP 36x3GSec: 36-Port SAS Expander with Zoning
PM8399 SXP 24x3GSec: 24-Port SAS Expander with Zoning

Author: Karin Gilles, Corporate Communications,
Hitachi Global Storage Technologies

Data center workloads have increased exponentially in recent years, requiring IT managers to find new ways of scaling their enterprise storage resources so that they are both highly reliable and cost effective. With the introduction of complementary serial interface technologies, IT managers now have the flexibility to deploy either high-performance Serial Attached SCSI (SAS) drives or cost-effective Serial ATA (SATA) drives (or both) in a SAS environment.

This approach to tiered storage allows IT managers to control costs and pair the less frequently used data with lower cost-per-gigabyte hard drives, while freeing high-performance SAS drive resources for mission-critical applications.

Author: Steve Denegri
Independent Data Storage Analyst

The Industry in Aggregate

It may have taken longer than expected, but RAID arrays equipped with SAS are now shipping. IBM is the first to get in the game with the launch of its EXP3000 array at the end of August. Soon to come are SAS-based RAID boxes from the likes of Dell, EMC, Hitachi, HP, and Sun. NetApp enters the fray, too, with filers based on SAS by year-end.

Almost universally, the new SAS-based external storage boxes feature 3.5" disk drives. The IBM EXP3000 deploys a single RAID controller and twelve SAS drives in a 2u shelf, giving it the capability to pack almost 4TB in the configuration. Though SAS drives are available in both 2.5" and 3.5", most in the industry agree that 2.5" SAS drives will primarily reside in performance-centric enterprise servers and not external arrays since the smaller size means less capacity per unit. This allows for maximum capacity as storage needs expand. Meanwhile, expect value-based servers to adopt 3.5" SAS drives in order to save cost.

Author: Tonya Comer, Product Marketing Manager, Industry Standard Servers,
HP

Introduction

As organizations address their growing storage needs, they are also facing changes within their computing needs. This means that they need a server configuration that is flexible and adaptable. They also need a standard tool set for configuring, expanding and managing the array controllers. And it all has to come at an affordable price.

The new HP controller combines the benefits of better performance, increased server uptime, and proactive monitoring, all while providing the investment protection customers have come to expect with HP's Smart Array family of controllers. The HP Smart Array E200 and E200i are the first entry-level controllers utilizing PCI Express and they also provide RAID 0, 1 and 1+0 support with an upgrade path to RAID 5 by adding Battery-Backed Write Cache (BBWC). The E200i is the embedded version of this array controller that ships in selected server units, based on customer order specifications.

Author: Brad Corrion, Product Marketing Engineer
Intel Corporation

The evolution and innovation of a new technology generally is paced by the demands of its user base. New technologies can grow and adapt quickly, rapidly responding to the needs of a small user base. Ironically, when the technology becomes popular and entrenched, the innovations focus on extending the shelf life of the current technology to minimize user disruption. For example, parallel shared bus architectures such as PCI were made wider and clocked faster in order to move more data more quickly, but without significantly altering their underlying architecture to support backward compatibility.

When simple extensions no longer address fundamental technological challenges, radical reinvention occurs. The best bits are retained and the rest is reconsidered. Again, consider the parallel shared PCI bus that is quickly being replaced with the serial, point-to-point PCI Express bus. They share many conventions and compatibilities, but the technologies are fundamentally different.

Similarly, the storage industry is witnessing SCSI's big leap to Serial Attached SCSI, or SAS. Like PCI Express, SAS drastically reduces the scalability and design challenges of parallel SCSI while also bringing new capabilities which parallel SCSI could not offer. Timed to leverage SAS adoption momentum, the recently launched Intel IOP34x Storage Processor Family integrates SAS/SATA controllers into the sixth generation of Intel's I/O processor line to provide end-product ease of use, data protection, and the flexibility of multi-protocol storage technologies.

Author: Sam Barnett, Product Line Manager, Serial Attached SCSI and Serial ATA Storage & Storage Networking Products, Storage Products Division,
Vitesse Semiconductor

As first generation systems based on Serial Attached SCSI (SAS) technology enter the market, leading server and storage OEMs are racing to deliver the next group of platforms based on an ever-evolving technology landscape. Vitesse opted to enhance its popular NexSAS™ product family concurrent with the release of generation 1 systems. This leap-frogging approach to the deployment of SAS technology has led to the introduction of many new products with features found only in high availability, superior performing, Fibre Channel systems today. Comprised of three new high-PHY-count expanders, two new RAID-on-CHIP offerings, extensions in intelligent mux/de-mux devices, a new enclosure management/SAS backplane controller, and high-rate, agile signal conditioners, the NexSAS™ line delivers on the promise of high-performance storage solutions for SMB (small/medium business) as well as enterprise systems.

Author: Don Jeanette, Senior Manager, Product Marketing
Fujitsu Computer Products of America

Adoption is Happening:
For nearly two years, a variety of Serial Attached SCSI (SAS) products has been available in the marketplace. In 2006, the hard disk drive (HDD) industry anticipates shipping as many as 2.5M to 3M enterprise products with SAS as the preferred interface. This will represent approximately ten percent of the overall enterprise hard disk drives shipped for the year. In parallel, it is evident that small form factor (SFF) SAS hard disk drives are continuing to gain momentum.

Author: Paul Vogt, Director of Product Marketing,
Adaptec

With Serial Attached SCSI (SAS) now widespread in the marketplace, developers have new freedom to create a single storage solution that meets a variety of price, performance, capability, and reliability needs. By having one SAS storage system meet the full spectrum of application requirements, development budgets can be reduced from previous generations where multiple products were required to meet multiple application requirements.

In addition to this flexibility, SAS offers a number of important benefits, including new levels of scalability, performance, and robustness.

Authors: Michael Sebesta and Joseph Rebrovich
System Integration Test Lab
Hitachi Global Storage Technologies

Serial Attached SCSI (SAS) is a new serial interface for enterprise hard disk drives that will eventually replace aging parallel SCSI technology. The new serial interface provides much higher data transfer rates, improved scalability and superior reliability. SAS is also compatible with Serial ATA (SATA), which has become increasingly popular for use in nearline and entry-server applications. The SAS architecture allows IT managers to deploy either high-performance SAS or cost-effective SATA drives in the same storage enclosure, providing unprecedented design flexibility for server and storage subsystem deployments.

New storage interconnects can often present system integration challenges. SAS is no exception, although SAS' unique development approach has, in many ways, helped to minimize the challenges.

Author: David So, Strategic Marketing Manager
LSI Logic

So maybe it took a little longer than some of us forecasted or hoped. For others, maybe it happened faster than they expected. But regardless of what any of us thought back then, it is now undeniable that Serial Attached SCSI (SAS) has finally landed, and in a big way.

SAS development time-line
Initial work on the SAS specification began in 2001, as the next evolution of SCSI technology, and it was ratified as an ANSI standard specification in late 2003. The first public demonstration of SAS prototype components actually took place in July 2003. And here we are, just over three years later. During those three years, numerous companies have announced production of SAS components as well as SAS promotional and educational events.

Author: Rachelle Trent, SAS Product Manager,
PMC-Sierra

As enterprise storage requirements rapidly increase, expanding data throughput and providing scalable storage capacity is crucial. The goal of Serial Attached SCSI (SAS) was to overcome the scalability and reliability limitations of parallel SCSI and to significantly improve the ability to add hard disk drives to a system. To overcome the scalability limitation, SAS uses devices such as expanders and multiplexers (muxes).

Expanders for scalability
SAS expanders provide scalability and enable fault tolerant systems by providing multiple connections between hard disk drives and initiator devices. These redundant links between hosts and drives maintain a connection in case of a system failure. In addition, SAS expanders provide high throughput and facilitate the compatibility between SAS hosts and Serial ATA (SATA) disk drives. Expanders simplify the configuration of large external storage arrays and can be cascaded with minimal latency while preserving bandwidth for increased workloads.

Excerpted from IDC Document #201478, "Worldwide Hard Disk Drive 2006-2010 Forecast: Record-breaking Years Lie Ahead."

Author: Dave Reinsel, Director Storage Hardware Research

The Industry in Aggregate

Calendar-year 2005 was a record-breaking year for the HDD industry from two perspectives: units and revenue. Surpassing the 2004 unit shipment record is no surprise, though the 24.4% increase to nearly 381 million drives surpassed all expectations. However, breaking the industry's old revenue record has received little attention. In 1997, the industry generated $27.8 billion in revenue. 2005 revenue came in at $27.9 billion, when rounded. It was close, but a record-breaker, nonetheless. This dynamic should not be overlooked given the difficult years the industry experienced immediately following 1997. Many question whether the same trend can happen again, but IDC sees the future in a positive light.

The component constraints that emerged late in 2004 lasted throughout all of 2005, especially with respect to glass and aluminum substrates. The limited supply of components coupled with manufacturing constraints among the HDD vendors created an environment of undersupply, moderate price declines, and unprecedented revenue growth.

Author: Sam Barnett, Product Line Manager, Serial Attached SCSI
and Serial ATA Storage & Storage Networking Products, Storage Products Division,
Vitesse Semiconductor

Serial Attached SCSI (SAS) offers a wealth of benefits to the enterprise server and enclosure customer (high reliability and performance, mixed enterprise/desktop drive support, improved economies of scale), and key to scalability and performance is the expander.

This article offers a brief technical exploration of SAS expander technology and its potential evolution into the "interconnect-fabric" of choice for midrange and enterprise storage systems of tomorrow.

The author assumes the reader has some knowledge of point-to-point storage architectures and SAS nomenclature. Detailed specification information on SAS can be found on the T10 website under http://www.t10.org/ (click "Drafts" then "Serial Attached SCSI (SAS)" under "Protocols and Physical Layers"). Similarly, the SCSI Trade Association (STA) also offers a robust set of tutorials on SAS. The reader may reference this material at http://www.scsita.org.

Author: Bill Schilling, Marketing Director/Enterprise Segment and Kent Bransford, Sr. Technical Editor
Seagate Technology

After months of speculation and anticipation, Serial Attached SCSI (SAS) storage solutions are now entering the marketplace in force. Given its unparalleled blend of performance, scalability and flexibility, it should come as no surprise that SAS is quickly making converts among IT professionals throughout the enterprise.

Yet some storage managers have been hesitant to adopt SAS, wary of the connection challenges this powerful new serial interface might entail. Having invested years of sweat equity to master the idiosyncrasies of parallel SCSI, they are understandably reluctant to risk a similarly steep learning curve with SAS.

Happily, SAS was specifically designed with a vastly more straightforward and robust connection architecture than parallel SCSI. Gone are the tedious shared bus issues (SCSI ID settings, drive termination, total cable length constraints, etc.) that plague parallel SCSI storage environments; SAS banishes such concerns with the elegant simplicity of point-to-point architecture.

Author: By Mike Micheletti, Product Manager
LeCroy Corporation

Administrators are often faced with choosing between a newer, more exciting technology or going with an existing, proven one. When it comes to server storage, the choice today is between the Serial ATA (SATA) hard drives and storage devices based on the Serial Attached SCSI interface (SAS).

SAS has become the next evolution of SCSI and significantly expands on the capabilities of its parallel predecessor. SATA has effectively replaced the ATA/Integrated Drive Electronics (IDE) standard that was used for years in desktop hard drives and CD/DVD drives. SATA drives have always been inexpensive and easy to work with, but they have also lagged behind SAS drives in terms of performance.

Author: Rachelle Trent, SAS Product Manager,
PMC-Sierra

SAS Provides Scalability

• Capacity: maximum 16K devices
• Expanders enable capacity scalability
• Bandwidth: in multiples of 3Gb/s
• Wide links provide bandwidth aggregation
• Increased storage capacity via cascaded JBODs

Author: Sam Barnett, Product Line Manager, SAS and SATA Storage Networking Products, Storage Products Division,
Vitesse

As connectivity and storage needs of the world business community continue to expand, high-performance, low-cost storage infrastructures and new storage networking technologies are required. Enter Serial Attached SCSI - its two tiered model - offering simultaneous support of both enterprise-class (high performance, high transaction I/O and extreme reliability) and desktop-class (high density with low cost) storage facilities -- are revolutionizing the way storage systems are designed and ultimately deployed.

Author: David So, Strategic Marketing Manager
LSI Logic

LSI coordinated a live, multi-vendor demonstration highlighting the performance benefits of SAS technology in a Microsoft SQL Server environment. The key messages for this demo were that SAS offers:

• Enterprise-level performance up to 2.4GB/s full duplex
• Enterprise-level capacity of over 16K targets
• Lower total cost of ownership
• An ideal solution for MS SQL Server data warehousing environments

Author: Linus Wong, Director, Strategic Marketing,
Adaptec

With its diverse requirements for high-performance storage for primary, mission-critical data and lower cost, higher capacity storage for secondary data, tiered storage has often required completely different primary and secondary storage systems. Building a tiered storage solution on a SAS infrastructure solves this problem, by allowing a single storage infrastructure to support both primary and secondary storage.

Author: Jay Neer, Corporate Strategic Product Manager,
Molex

The SAS Interconnect Infrastructure table displayed examples of the new connectors and cables implemented in the recent SAS 1.1 release. The new Mini SAS connectors developed by Molex for the standard are now appearing in SAS products from a number of companies. This interface provides more port density on host boards and enables higher bandwidth capability for transmitting data.

The internal Mini SAS is documented in the SFF Committee SFF-8087 Specification. This low-profile SMT connector provides four times the port density on host boards compared to the connector released in SAS 1.0. The AMCC controller card on display implemented four Mini SAS 4i connectors on a full size PCI card similar to the upper diagram on the sign.

Author: Mike Karp, Senior Analyst, Enterprise Management Associates

There cannot be much doubt that Serial Attached SCSI (SAS) is ready for prime time. The technology is new but evolutionary, and therefore it doesn't require much of a stretch for system builders to understand it. It is a proven technology: we have seen SAS work in the lab, at plugfests and in the field. It's hot pluggable, has a roadmap that will take it to 4X its current speed, it's cheaper to build than parallel SCSI, it plays well with the cheaper SATA technology, and it's highly scalable.

Additionally — and perhaps most importantly — it arrives on the scene (not coincidentally, of course) at a time when parallel SCSI, which has played a major role in protecting IT data since the 1980's, has reached what may reasonably be described as its end of life. Because something is a technical success however, even if the timing is right, does not necessarily guarantee that it will win in the marketplace. Remember the Betamax, which by most accounts was technically superior to the VHS videotape technology that eventually defeated it? Remember mini-super operating systems like VMS and PRIMOS? Many readers of this newsletter could make a good case for the fact that both were far superior to Unix in many ways, and yet both fell by the wayside.

Authors: Franco Castaldini, Sr. Product Marketing Manager
and Kent Bransford, Sr. Technical Editor, Seagate Technology

"If you fear change, leave it here!" may be the lighthearted counsel of cash-strapped baristas, but IT professionals know that proactively adopting change is serious business, a key to maximizing system performance and efficiency. Alas, pioneering storage technologies are often seen as double-edged swords, their gains coming at a stiff price in terms of purchase or deployment and integration.

Fibre Channel (FC) is a prime example of this phenomenon, coupling remarkable throughput and scalability with daunting cost. Beyond the substantial investment required for FC infrastructure itself, Fibre Channel solutions also entail complex deployment and management procedures that require highly specialized (and expensive) expertise not found in many IT departments. Hence FC has typically been limited to enterprises with the needs (and deep pockets) to justify its use.

Serial Attached SCSI (SAS) was specifically architected to avoid such pitfalls. By leveraging the best features of two familiar storage interfaces, SCSI and Serial ATA (SATA), SAS makes it surprisingly easy to upgrade existing SCSI servers and storage arrays. While delivering performance and scalability that rival Fibre Channel, SAS is far simpler (and less costly) to buy, install and maintain.

Author: Tonya Comer, Product Marketing Manager, Industry Standard Servers
HP

Just in time for today's storage explosion, Serial Attached SCSI (SAS) hard drive options provide a scalable, flexible, better performing and efficient solution for servers and for storage enclosures that go beyond the inherent limits of parallel technology. A recent study at the University of California at Berkeley found that the rate of storage performance is growing 30 percent year over year. According to the report, physical media is defined as "print, film, magnetic and optical - and seen or heard in four information flows through electronic channels - telephone, radio and TV and the Internet," that will at some point be stored for retrieval. This holds true at the enterprise data center level with data collection spanning email, security, and online and financial transactions.

Author: Mike Micheletti, Product Manager,
Lecroy Corporation

Serial Attached SCSI (SAS) is a storage interface developed to meet the needs of enterprise-class storage applications. Central to the SAS value proposition is the ability to scale storage systems beyond the limits of today's parallel SCSI using a switching technology called Expanders. Designed to provide fan-out architecture for SAS, expanders allow SAS initiators to connect up to 16,000 physical devices in a single domain.

Storage integrators are now busy validating multi-terabyte storage subsystems that include active backplanes containing multiple expanders with 64 or 128 disks in a single enclosure. The SAS architecture is designed to seamlessly scale performance as the number of targets increases. But, as with any new technology, integrators pushing the envelope with these external RAID configurations may encounter problems not seen in simple internal direct-attached storage (DAS) applications.

Author: Susan Bobholz, Intel Storage Group Ecosystem Enablement Manager
and member of the STA Board of Directors

The first generation of Serial Attached SCSI (SAS) products represents a major leap forward in storage technology. SAS drives have a full-duplex throughput of 3.0 Gb/s and are capable of providing a competitive advantage to enterprises that require fast access to data. While today's servers also have 3.0 Gb/s bandwidth, servers soon will be capable of communicating with storage at 6.0 Gb/s. On the other hand, the availability of 6.0 Gb/s SAS devices is expected to lag behind that of 6.0 Gb/s servers. In order to bridge the anticipated gap, the storage industry is looking for ways to take advantage of faster servers by aggregating bandwidth to communicate with multiple storage drives, e.g., enabling a 6.0 Gb/s server to communicate with two 3.0 Gb/s or four 1.5 Gb/s storage drives simultaneously. Bandwidth aggregation would enable businesses to take advantage of faster servers while still protecting their investments in current storage technology. Delivering this capability however, would have both technical and economic implications that must be considered.

Author: Tonya Comer, Product Marketing Manager
Industry Standard Servers, HP

Serial Attached SCSI (SAS) is a point-to-point disk interface that builds on the functionality of SCSI for the enterprise. Borrowing reliability and performance enhancements from Fibre Channel, SAS supports dual-port and full-duplex communication between servers and disk drives. SAS extends reliability and bandwidth opportunities by using expanders to create wide ports, which are multi-path connections between the server and storage solutions. SAS also improves manageability of the storage solution by providing the Serial Management Protocol (SMP) to monitor connections between individual devices and identify points of failure or reduced performance.

The first generation of SAS achieves bandwidth as high as 300 MB/s per link and operates in full-duplex mode, in which data, commands, or status information flow bi-directionally. The SAS interface allows for combining multiple links to create 1x, 2x, 3x, or 4x connections for scalable bandwidth. In contrast, Ultra320 SCSI has a half-duplex bandwidth of 320 MB/s per channel.

Authors: Franco Castaldini, Sr. Product Marketing Manager and
                   Kent Bransford, Sr. Technical Editor
                   Seagate Technology

"Efficiency" is the watchword in today's enterprise as it strives to achieve the optimal blend of performance and cost-effectiveness. To be sure, this can be a delicate balance. Investing in unnecessarily powerful (and costly) solutions is wasteful, yet deploying inexpensive (and underpowered) solutions can seriously degrade system performance and overall productivity. In either case the bottom line ultimately suffers.

Fortunately, the enterprise's heightened focus on efficiency coincides with an unprecedented variety of storage options from which to choose. Spearheaded by Serial Attached SCSI (SAS), a comprehensive range of serial-based solutions now enables savvy IT managers to hit the "sweet spot" of performance and cost-effectiveness by specifying the most appropriate storage device for any given application.

Storage Selection Criteria
To determine which serial disk drive is the most appropriate solution for a specific application, four evaluation criteria can be applied:

• Performance
• Reliability
• Scalability
• Price

Author: Doug Pickford, Director of Product Planning and Strategy,
Hitachi Global Storage Technologies

Hitachi Global Storage Technologies has been working with HP and numerous other companies to help define the Serial Attached SCSI (SAS) standard and deliver products to the marketplace. We recently caught up with HP's Jeff Jenkins to discuss SAS in greater detail, including the benefits he believes it will afford to HP customers.

As vice president of server storage and infrastructure at HP, Jeff's organization is working to ensure that HP's enterprise customers realize maximum performance, reliability and flexibility from their SAS-based systems.

Author: Mike Micheletti, Product Manager
LeCroy Corporation

Now that component vendors Serial Attached SCSI (SAS) are shipping in volume, storage integrators are rolling up their sleeves to begin evaluating this powerful new storage interface. Anxious to harness superior performance, these SAS developers are testing hosts, devices and storage subsystems for compatibility and reliability. Early adopters are impressed to see their legacy SCSI applications running on top of SAS storage volumes without modification. But is SAS robust enough to replace parallel SCSI in mission critical applications?

Author: Rachelle Trent, SAS Product Marketing Manager

PMC-Sierra's maxSAS™ storage family includes Serial Attached SCSI (SAS) expanders, SAS/Serial ATA (SATA) retimers, SAS/SATA multiplexers and enclosure management processors. To accelerate OEM and ODM development cycles for tiered storage disk arrays, PMC-Sierra provides complete reference systems for its entire maxSAS product line.

The latest editions to PMC's maxSAS family include SAS expander switches with zoning support and intelligent SATA active/active multiplexers. A complete SAS/SATA storage system solution can be realized by using PMC's SAS expander switches combined with the intelligent active/active SATA multiplexers.

Author: Charlie Kraus, Director, HBA Business Unit
LSI Logic

After enjoying an amazing run of longevity and evolution, parallel SCSI is finally seeing the end of its reign, to be replaced by Serial Attached SCSI (SAS). SAS builds on, and improves on, the parallel SCSI foundation and succeeds Ultra320 SCSI on the industry roadmap:

Table 1: Serial Attached SCSI Roadmap.
Source: SCSI Trade Association, 2005

Author: Tonya Comer, Product Marketing Manager, Industry Standard Servers,
HP

IT managers have traditionally had scant flexibility when choosing a data center storage solution. Their options were limited to separate systems based on parallel Advanced Technology Attachment (ATA), Small Computer Systems Interface (SCSI) or Fibre Channel disk interfaces. These storage options constrained the IT manager's ability to deploy and redeploy core technologies, thereby often adding a significant cost and management burden to the overall enterprise. With the advent of serial I/O architectures, key solution providers, such as HP, can now provide one system or storage solution that will meet the requirements for a broad range of storage applications. This will enable IT managers to standardize on a single server or storage platform, dramatically reducing the complexities of managing storage applications in today's data center.

HP's Serial Attached SCSI (SAS) and Serial ATA (SATA) solutions are the next generation in storage technology, offering better performance, flexibility and scalability. HP has been instrumental in driving the direction of SAS and SATA technologies within the industry. HP designs solutions that are the most advanced and most thoroughly tested, in order to provide the best customer experience possible. HP has ensured that key contributors are unified in the industry direction and development of this monumental technology.

The direction that HP is taking this technology is based on feedback from users—overwhelmingly, the customer has requested a transition from the existing SCSI platforms to the small form factor (SFF) SAS platform. Product development addresses customer pains relating to heat management of newer generation processors by creating drives that draw half the power of their predecessors. It also addresses concerns around physical space constraints, as well as general IT issues such as performance, metrics and density.

Author: Linus Wong, Director, Strategic Marketing
Adaptec

Adaptec offers solutions that integrate a broad range of Serial Attached SCSI (SAS) products, from RAID controllers and host bus adapters to internal storage enclosures and external arrays. These solutions are built on a platform that enables products to be easily mixed and matched to meet specific storage needs and are also integrated into existing storage environments without retrofitting.

Authors: Franco Castaldini, Sr. Product Marketing Mgr. and Kent Bransford, Sr. Technical Editor,
Seagate Technology

As the pace of Serial Attached SCSI (SAS) product introductions continues to accelerate, IT managers enjoy an increasingly broad range of SAS storage solutions from which to choose. While the inherent performance advantages of SAS disk drives are certainly compelling, savvy IT professionals are even more excited about the revolutionary role SAS will play in the larger context of storage infrastructures.

Storage is entering a new era of cost-effectiveness and efficiency, driven by the growing movement towards specialized storage solutions. The value proposition of such storage is straightforward: Optimize price/performance by matching the storage device to the specific characteristics of the data and/or storage environment. SAS is a fundamental enabling technology in this specialization revolution, seamlessly integrating multiple types of storage devices in one enterprise-class infrastructure.

Author: Sam Barnett, Product Line Manager for Serial Attached SCSI and Serial ATA,
Vitesse Semiconductor

The NexSAS™ family of Serial Attached SCSI (SAS) products from Vitesse offers server and storage enclosure OEMs, ODMs, and contract manufacturers (CMs) the industry's most comprehensive portfolio of solutions for the emerging SAS market. Comprised of edge expanders, fanout expanders, RAID-on-CHIP offerings, intelligent mux/de-mux devices, discrete enclosure management/SAS backplane controllers, and rate-agile signal conditioners, the NexSAS™ line delivers on the promise of high performance storage solutions for SMB (small/medium business) as well as enterprise systems.

The Vitesse NexSAS™ product family is divided into four functional areas: expander technology, RAID-on-CHIP, SAS/SATA Support devices, and Enclosure Management. This article explores the NexSAS™ expander and RAID-on-CHIP technology in detail.

Author: Jim Pascoe, Hitachi Corporate Communications, interviewed Gary Goodwin, Firmware Development Engineer Hitachi Global Storage Technologies

In the following interview, Gary Goodwin of Hitachi Global Storage Technologies (Hitachi GST) reviews some of the key issues related to Serial Attached SCSI (SAS) scalability and how systems integrators (SIs) and other end-users deploying SAS-based storage are expected to benefit from the transition from parallel SCSI to SAS.

Gary Goodwin is a firmware development engineer at Hitachi GST with an extensive knowledge of Ultra320 SCSI, Fibre Channel and SAS. He has had a long career working with computer storage interface technologies. SIs will benefit from Gary's expertise presented in question and answer format.

Author: Linus Wong, Director Strategic Marketing and Tom Treadway, CTO
Adaptec

For the past five years, your only choice for developing a high-availability, highly scalable and reliable storage subsystem has been to use a Fibre Channel (FC) storage area network (SAN)-based architecture. A number of key features have established FC as the platform of choice for the highest storage performance. It provides:

• Enterprise-class reliability
• 1 and 2Gb/s bandwidth, with 4Gb/s products entering the market now
• Support for multiple topologies
• Scalability up to hundreds of servers
• Flow control to eliminate congestion
• Mature set of storage network services

However, FC has not proven to be a universal solution because its price point and maintenance requirements have put its level of reliability out of reach of smaller organizations. For businesses that need low-end networked storage, Serial Attached SCSI (SAS) can provide similar reliability at a far more affordable price.

Although SAS was originally designed to replace the aging parallel SCSI interface as an inside-the-box connection in direct-attached storage (DAS) implementations, it actually has many of the qualities of a network fabric. For example, it scales easily without downtime by using expanders the way switches are employed in FC architecture. Like all multi-node environments, SAS allows multiple hosts to access various storage systems and also provides redundancy, offering multiple paths for a host to access its data.

Author: Martin Czekalski, Interface Architecture Initiatives Manager
Maxtor Corporation

Well, with a variation of that now-classic line, it all depends on what your definition of "fabric" is. If your definition includes a large computer room, campus infrastructure environments or generalized network capabilities, then the answer is "No." For example, if you have multiple computer rooms full of servers and storage area network (SAN)-attached storage with the need to connect a cross-campus environment, then either a Fibre Channel (FC) or IP-based SAN is going to be the obvious choice. These protocols and interconnects allow for a high degree of connectivity as well as long cabling distances. However, many applications that currently use SANs are much more bounded, and could easily be satisfied by using Serial Attached SCSI (SAS). Let's look at some usage models and see how SAS can provide many of the same features as a SAN in these bounded environments.

Author: Charlie Kraus, Director, HBA Business Unit
LSI Logic

Adoption of the next evolutionary step in SCSI technology, Serial Attached SCSI (SAS), is well underway, with announcements from major OEM storage vendors starting to appear. Initially the role of SAS was understood to be the next direct-attach technology for internal disk drives in servers, or for external drives in SAS JBODs. We will see just such applications of SAS technology in the beginning. But there are other aspects to SAS that will have wide-ranging implications and prove disruptive to current strategies for building storage systems.

Author: Samuel J. Barnett
Product Line Manager, Serial Attached SCSI Products
Vitesse

IT Insights
Mention Serial Attached SCSI (SAS) technology to a room full of IT professionals and the air is immediately charged with excitement. Take the dialogue one step further and associate SAS with Fibre Channel front-ends/fabrics/switching or a SAN and the mood turns noticeably somber.

While Serial Attached SCSI offers a wealth of benefits to the enterprise server and enclosure customer (high reliability and performance, mixed enterprise/desktop drive support, and improved economies of scale), the thought of yet another SAN technology initially concerns the majority of the end-customer community. Legacy deployments of 1, 2, and now 4Gbps Fibre Channel in conjunction with costly director-class switches make a wholesale technology shift difficult at best, while other promising technologies like iSCSI further divide the end-user community.

Author: David Woolf - Senior Technical Staff
University of New Hampshire InterOperability Lab

When it comes to data storage and protection, small and medium businesses (SMBs) often find themselves not knowing where to turn for data storage solutions. They are torn between high-end product offerings intended for large enterprises, or trying to piece together a data storage solution from products intended for home users.

Like a large enterprise, a small or medium business has increasing data storage needs as the business grows. Data is a critical part of any business. Also like a large enterprise, a small business needs scalability, backup, and possibly some form of information life-cycle management (ILM).

In many cases the best solution for these needs is a storage area network (SAN), but SANs are expensive. Although the price for SAN equipment is decreasing, the high cost of the initial investment remains, making it prohibitive for a small business. An SMB does not always have the resources necessary to devote to an IT staff to support its storage needs. SMBs need a storage technology that allows flexibility, ease of use, and a lower total cost of ownership.

Author: Ahmad Zamer, Manager, Storage Industry Initiatives, Intel Corporation

Pacing SAS Adoption Progress
The apparent eagerness for higher performance Serial Attached SCSI (SAS) calls for a pause to look at the allocation of industry synergies as we push for SAS adoption. There is no doubt that the future of SAS depends on its successful adoption over the next few years and all effort should be focused on driving the highest possible adoption rates. In addition to that, all proposed new enhancements should be embraced proportionally to their ability to facilitate SAS adoption. Driving successful SAS adoption takes precedence over other considerations, for without it; future SAS generations may not evolve. At this time, an updated version of SAS (1.1) is on its way to becoming an industry standard. Even before that version is complete, discussions are starting on the next generation, a faster version of the technology known as SAS-2. The expectation is that SAS will last a long time, so there is no urgency to rush headlong into the next generation of SAS technology.

Author: Franco Castaldini, Sr. Product Marketing Manager, and Kent Bransford, Sr. Technical Editor Seagate Technology

Introduction
To successfully compete against today's enterprise behemoths, small- and medium-sized businesses/enterprises (SMBs/SMEs) rely on their superior agility and rapid adaptability to ever-changing business challenges. Lacking the deep pockets of their outsized rivals, SMBs/SMEs simply cannot afford to be caught flatfooted. Lumbering along in reactive mode is often costly to a large enterprise, but to an SMB/SME it can be fatal.

So it's no surprise that SMBs/SMEs bring a decidedly proactive perspective when contemplating investment in storage solutions. It's not enough for a new storage system to cost-effectively address current needs—it must also have the power and flexibility to seamlessly keep pace as storage requirements inevitably evolve. Achieving this balance of efficiency, performance and expandability has been an elusive goal for the SMB/SME community...until now.

Author: Tonya Comer, Product Marketing Manager, Industry Standard Servers, HP

Serial Attached SCSI (SAS) holds the promise of the future for SMB users who will eventually need more input/output per second (IOPS) performance, easier connectivity and greater scalability, as storage requirements continue to escalate. As SAS products begin to enter the market in 2005, SMB customers will appreciate the time and effort that has gone into the definition, development, and standardization of this innovative refinement to long-standing SCSI technology.

More affordable for SMB customers than Fibre Channel and more robust and reliable than Serial ATA (SATA), SAS will be able to fulfill the SMB customer requirements and provide the necessary performance and scalability to move data at gigabit speeds—speeds that meet or exceed current storage I/O performance found in Parallel ATA (PATA), SATA, SCSI or Fibre Channel systems.

Author: Tonya Comer
HP

In today's data center, customers use Fibre Channel, parallel SCSI, or parallel ATA (PATA) technologies for their hard drive needs. With increasing performance demands, it is more difficult for the current parallel buses to meet these demands.

A logical transition is necessary if SCSI and ATA are to meet the recent performance and management needs; thus the evolution to serial technology. Serial technology will overcome the performance limitations of today's parallel buses and will enable future growth.

Rachelle Trent, SAS Product Marketing Manager, PMC-Sierra

As enterprise storage requirements rapidly increase, expanding data throughput and providing scalable storage capacity is crucial. System Integrators (SIs) need to understand the new features of expander devices now, in order to be ready for market adoption of Serial Attached SCSI (SAS). The SAS standard specifies expanders, which are inexpensive switch devices connecting SAS hosts to SAS targets as shown in Figure 1 below.

Figure 1: A SAS Expander performs a data switching function between multiple hosts and target devices.

Author: Martin Czekalski, Maxtor Corporation

Server blades first appeared about two years ago as a way to deliver increased server compute capabilities within a small footprint. Server blades are offered in a wide range of performance and packaging options. High-density blades (Figure 1) offer modest performance with a focus on low power and high packaging density to maximize the number of servers per rack. This high-density form factor has typically used mobile drives for low power. High performance blades (Figure 2) are focused on providing the maximum compute power in a given space, hence they typically use higher performance enterprise drives (10K and 15K) in a 3.5" form factor. Both blade types utilize a direct-attached storage model for these embedded drives. Additional storage is typically provided by some form of fabric-attached storage (NAS or SAN).

Author: David So, LSI Logic

Video on demand. Tivo. On-line gaming. Digital photography and videography. Video and audio editing. E-mail archives. New SEC and federal regulations (SEC 17a-4, Sarbanes-Oxley, HIPAA, etc.). The increasing need for storage capacity continues down a seemingly endless path, and the timing for Serial Attached SCSI (SAS) couldn't have been scripted any better. SAS introduces greater storage scalability and the ability to access that storage faster than ever before.

SCSI is Good
Today's dominant disk drive interface in the enterprise server and direct-attach storage markets is Ultra320 SCSI, a parallel SCSI speed bump that is nearing its end in innovation. As has been announced by the SCSI Trade Association, the next evolution of SCSI technology beyond Ultra320 is SAS. While Ultra320 SCSI offers many benefits over other currently available I/O interfaces and has served the market well, its physical limitations leave something to be desired as data centers clamor for even greater capacity and higher bandwidth. Parallel SCSI is limited to 15 target devices per bus, and a shared bus at that. With today's prevalent dual-channel SCSI host bus adapters, that's a total of 30 disk drives per HBA.

Author: Linus Wong
Director, Strategic Marketing, Adaptec

Serial Attached SCSI (SAS) leverages the 20-year evolution of the SCSI protocol, carrying forward its trusted reliability and stable feature set. Since its inception three years ago, SAS has promised new levels of scalability, flexibility, and cost-effectiveness for connectivity, data transport, and data storage.

The announcement of the first prototypes in 2003 marked a major milestone in the transition from drawing board to mass market availability. Since then, the first generation of technologies and products that will bring the benefits of SAS into the enterprise have been developed and tested, and a variety of integrated solutions have been demonstrated at numerous venues.

Author: David So
LSI Logic

The many features and benefits of Serial Attached SCSI (SAS) have been touted in previous editions of Serial Storage Wire. As the next evolution of SCSI technology, and with the support of numerous industry powerhouses, SAS is poised to be the dominant I/O interface in the enterprise market, gradually replacing Ultra320 SCSI in that space and extending the industry's most dominant interface for many years to come. In fact, because of its scalability, greater performance, high availability, and flexibility in supporting both SAS and Serial ATA (SATA) disk drives, SAS is predicted to make great inroads into the storage systems market as well, where parallel SCSI penetration, although successful, never quite reached its full potential. The promised transition to SAS has officially begun, as many companies have recently announced (or soon will announce) production availability of various SAS components. Q1 2005 will see SAS move beyond the prototype phase and into customer applications.

Author: Marty Czekalski
Maxtor Corporation

As Serial Attached SCSI (SAS) products start to roll out over the next several months, IT managers can feel confident in purchasing storage solutions based on SAS. Not only will SAS serve the storage needs of today's systems, but it will also enable a new range of capabilities previously unavailable in small to midrange servers and systems.

Many of these features have been discussed in previous issues of Serial Storage Wire and include; enhanced performance, scalability, reliability and availability and, in addition, compatibility with both SATA and SAS disk drives. These features not only address a broad range of price-performance points for storage subsystems, but also enable the concept of tiered storage and Information Lifecycle Management (ILM) to be applied to systems targeted at Small to Medium Businesses (SMBs) and branch office environments.

Author: Linus Wong, Director Strategic Marketing
Adaptec

One of the key considerations in developing a new technology is interoperability. As witnessed by the early issues with Fibre Channel solutions, market acceptance of a new technology, no matter what performance gains or cost reductions it provides, will be slowed by interoperability doubts.

As a result, interoperability has been a focal point throughout the development of the Serial Attached SCSI (SAS) technology standard and products. SCSI Trade Association and its members are committed to providing fully interoperable products, and in 2004, three plugfests at the University of New Hampshire InterOperability Laboratory tested for both SAS and Serial ATA (SATA) compatibility and multi-vendor interoperability. Components tested for interoperability included disk drives, controllers, test equipment, cables, connectors and systems. The fourth SAS plugfest, held April 25-29, 2005, continued this commitment.

This electrical level interoperability testing provides peace of mind that products can be connected to other products from multiple vendors and integrated into existing environments. However, creating SAS solutions, particularly early in the adoption process, requires more than hardware interoperability.

By Rachelle Trent
PMC-Sierra

As enterprise storage requirements rapidly increase, expanding data throughput and providing scalable storage capacity is crucial. One of the goals of Serial Attached SCSI (SAS) was to overcome the scalability limitations of parallel SCSI and significantly improve the ability to add hard disk drives to a system. Parallel SCSI is a shared bus architecture that utilizes common connection paths between devices. The shared connection limits scalability, and adding more buses with multiple initiators does little to extend the scalability.

Author: Rachelle Trent
PMC-Sierra

As enterprise storage requirements rapidly increase, expanding data throughput and providing scalable storage capacity is crucial. System Integrators (SIs) need to understand the advantages and architecture of devices called "expanders" now, in order to be ready for market adoption of Serial Attached SCSI (SAS). The SAS standard specifies expanders, which are inexpensive switch devices connecting SAS hosts to SAS targets as shown in Figure 1 below.

Figure 1: SAS Expanders Perform Data Switching Functions Between Multiple Hosts and Target Devices.

Author: Jim Pascoe, Hitachi Global Storage Technologies

Data center workloads have increased exponentially in recent years, requiring IT managers to find new ways of scaling their enterprise storage resources in a manner that is both highly reliable and cost-effective. With the introduction of complementary serial interface technologies, IT managers now have the flexibility to deploy either high performance Serial Attached SCSI (SAS) drives or cost-effective Serial ATA (SATA) drives in a SAS storage environment. Hardware compatibility between the new interfaces will provide unprecedented design flexibility for server and storage subsystem deployments.

SAS was designed to be the successor to parallel SCSI, which has been used effectively as an enterprise storage interface for more than 20 years. Maintaining compatibility with the last 20 years of application software investment, SAS supports the SCSI command set and protocol. SAS will support faster data transfer rates and more devices per controller, as well as reduce the size and complexity of the cables and connectors (thus enabling smaller, more densely-packed disk arrays).

Author: Franco Castaldini and Kent Bransford
Seagate Technology

Serial Attached SCSI (SAS)/Serial ATA (SATA) compatibility produces unprecedented storage synergies and efficiencies, enabling enterprises to meet both performance and capacity requirements with a single SAS infrastructure. SAS drives deliver the speed, reliability and scalability demanded in high-availability enterprise environments, while high-capacity SATA nearline drives are purpose-built for bulk storage applications, combining low cost per GB and enhanced reliability.

And now the SAS value proposition grows even stronger with the arrival of small form factor (SFF) 2.5-inch enterprise drives. These drives are spearheading a new class of high-I/O-density storage solutions that facilitate rapid and cost-effective storage consolidation. SFF 2.5-inch drives are 70 percent smaller than conventional 3.5-inch 10K drives, enabling them to deliver 130-150 percent greater system performance in the same footprint. They also use 40 percent less power and run cooler, reducing airflow requirements and enabling greater storage density.

Author: Tonya Comer, HP

Three years ago the Serial Attached SCSI (SAS) and Serial ATA (SATA) industry working groups developed specifications for serial I/O technologies that will provide the flexibility and performance that IT managers need for storage products and solutions in the future. SCSI Trade Association (STA) member companies have worked together in the interim developing SAS technology to ensure quality products for reliable, quick-time-to-market SAS solutions. SAS solutions will be implemented in enterprise-class data centers, delivering the full functionality of enterprise-class systems and subsystems such as hard disk drives (HDDs). SATA solutions will be implemented in desktop PCs and low-cost, non-mission-critical server storage solutions.

Author: David Allen
Vitesse Semiconductor

With the advent of new technology often comes new terminology and updated definitions for familiar concepts. Engineering and standards communities strive to precisely define concepts and functions using terminology applicable to the technology. The Serial Attached SCSI (SAS) standards community is no different, and has defined specific terminology for the physical and link layer functions surrounding SAS links. Addressed in this article is a clarification of the definitions and terminology surrounding SAS connections.

Author: David Woolf, Senior Storage Research Engineer and Principle SAS Consortium Engineer,
University of New Hampshire-InterOperability Laboratory (UNH-IOL)

This is an exciting time for Serial Attached SCSI (SAS). Its development curve has been extraordinarily smooth and swift, products are now launching and market entry will accelerate as 2005 goes forward. The last of the dust clouds are dissipating, and it's becoming clearer what role SAS will play in the near- and not-so-near-term data center market.

Greasing the Skids
The rapid SAS market ramp-up owes much to the forethought and careful planning of key engineering players and organizations like the SCSI Trade Association (STA). In fact, SAS' smooth transition from the engineering white board to the marketplace should be taken as a model for successful technology development. This process succeeded for two key reasons: First, SAS didn't reinvent the wheel. Its development incorporated and built upon older, well-established technologies such as SCSI and the trusted XAUI (see definition two paragraphs below) physical layer. Second, interoperability tests were built into the development process from the start. Amazingly, this is not necessarily the rule with new technologies.

Author: David Allen, Director of Strategic Marketing, Storage Products Division
Vitesse Semiconductor

Serial Attached SCSI (SAS) expander architectures provide flexible, cost-effective connections for internal and external storage subsystems in the mid-range and enterprise server markets. In this article we address SAS expanded architectures applicable to both server and storage enclosure applications.

Expander Types and Features

SAS Edge Expanders and Fan-out Expanders provide switching for connecting multiple targets to a host connection. Edge expanders support up to 128 SAS PHYs. Similarly, “Edge Expander Device Sets” can be constructed from multiple edge expanders. Direct connections, subtractive connections, and limited table routing enable communication between individual expanders (see Figure 1). Because they employ limited table routing, edge expanders are targeted at low-cost designs with limited storage scalability requirements.

Author: Mike Micheletti
Computer Access Technology Corp. (CATC)

Scalability can be defined as "the ease with which a solution or component can be modified to fit the problem as the size of the problem increases". Scalability in the storage domain allows IT managers to respond to changing storage requirements within the enterprise, and is a stated design goal of Serial Attached SCSI (SAS).

The SAS protocol delivers scalability via Expanders, integrated circuits (IC) that function as switch components and route frames between initiators and end-points. By providing multiple point-to-point drive connections in a single IC, expanders allow aggregation of bandwidth between Initiator and multiple SAS disk drives. Expanders also enable an architecture that accommodates dynamic discovery and configuration as new components are added to the system.

Authors: Franco Castaldini and Kent Bransford
Seagate Technology

The arrival of Serial Attached SCSI (SAS) marks a new era in storage scalability, wherein both the type and quantity of drives can easily be optimized. SAS compatibility with Serial ATA (SATA) enables seamless deployment of desktop-class SATA drives and enterprise-class SAS drives in the same SAS domain, giving IT managers unprecedented flexibility to specify the most appropriate drive for both online (transactional, high availability) and near-line (archival, low availability) duties. Moreover, employing a common SAS infrastructure for both types of drives minimizes hardware redundancy, further enhancing efficiency.

Author: Ahmad Zamer
Intel Corporation

On a recent trip to the North East, I had the opportunity to visit the data centers of two corporate customers. The first was an Internet Service Provider (ISP), the second, a mid-size brokerage firm. Both organizations, despite their different businesses, spoke of similar challenges their Information Technology (IT) staffs face. They also spoke of similar needs they wanted to be able to meet using new technologies.

Real-World Data Center
The ISP's manager of data center operations spoke in terms that may not be unfamiliar to technical people who work on industry standard and storage product design. He talked about his needs and challenges in terms of how they relate to floor tiles. He measured the value and utility of every storage and server solution in terms of how much precious real estate they would occupy in his data center. Following a three-hour tour and lecture from the data center director, one finds it hard not to measure everything using the "tile factor."

From the ISP's perspective, the major challenges were the limited power, per tile, they can bring to the data center, and the ever-rising costs of cooling per tile. These are simple metrics that have serious implications for all new computing technologies, especially storage technologies. Pointing to huge boxes scattered across the data center, our guide shouted, "Do you see these huge boxes? These are my storage boxes and I don't seem to ever have enough." So, how can one keep adding big storage boxes to the enterprise infrastructure without negatively impacting the tile factor?

Author: Sam Sawyer
Hitachi GST

The new serial interfaces, Serial Attached SCSI (SAS) and Serial ATA (SATA), have been designed to replace their parallel predecessors. They will support faster data transfer rates and more devices per controller, as well as reduce the size and complexity of the cables and connectors (thus enabling smaller, more densely-packed disk arrays). System builders will also be able to integrate SAS and SATA hard drives in a single enclosure.

SAS goes beyond SATA by adding dual porting, full duplex and device addressing; furthermore, it offers higher reliability, performance and data availability services, as well as logical SCSI compatibility. SAS will continue to enhance these and other metrics as the specification evolves, including increased device support and longer cabling distances.

Author: Paul Griffith
Adaptec, Inc.

Why Choose SAS?
The topmost factor in choosing a storage subsystem for enterprise system development is reliability. Maintaining user access to valuable data reduces total IT costs and increases user productivity. Serial Attached SCSI, a serial bus architecture, has emerged to deliver higher levels of reliability than parallel SCSI for mission-critical, transactional applications that must be online around the clock with no data loss.

To ensure continuous data access when a disk drive fails, multiple initiators have long been used in enterprise computing to provide disk drive access to multiple hosts and host bus adapters or both - an approach that doesn't work well in parallel technology configurations because doing so produces single points of failure that can block access to a device and ultimately to critical data.

A developer benefits from utilizing serial bus architectures that overcome this shortcoming in reliability by supporting a network of dedicated point-to-point device connections and eliminating the single point of failure. The connections also provide full bandwidth to each storage device to boost system performance. By contrast, multi-drop parallel bus architectures share total bandwidth among devices.

Author: Harry Mason
LSI Logic

An often over-looked aspect of system reliability is software quality. Software quality improves as the software is used in real world applications and as it undergoes revisions, until the failure rates are quite low. In short, software run time is a necessary requirement to deliver highly reliable enterprise-class storage solutions.

Serial Attached SCSI (SAS) was architected from the beginning to leverage more than two decades of legacy SCSI software. As such, the middleware applications that have supported SCSI over this lengthy period of time can be reused without sacrificing any enterprise-proven functionality.

Author: Martin Czekalski
Maxtor Corporation

Reliability, availability, and scalability are the cornerstones of online transaction processing (OLTP) and enterprise class computing systems and storage subsystems. In this issue of Serial Storage Wire we will cover the first two as they apply to Serial Attached SCSI (SAS) and cover scalability in the next issue.

Reliability
The terms reliability and availability are often misunderstood and used interchangeably, when in fact they refer to two different attributes of a system or its components. For example, a component's reliability is typically specified as Mean Time Between Failure (MTBF), which represents the mean number of component hours accumulated between failure events when a large sample of components is run in operation. Another important aspect of reliability is the ability to detect errors when they occur and take appropriate action so as not to adversely affect the integrity of a system or its data (error detection and containment).

Availability
Availability, on the other hand, is the percentage of time a system or component is available for use. To calculate availability, additional factors beyond MTBF need to be factored in such as Mean Time to Repair (MTTR) and the overall system architecture. In many cases individual system components can fail while not affecting the availability of a system (e.g. RAID systems can usually remain available, even if a single disk drive fails).

Stephen Schaeffer, Manager of University of New Hampshire InterOperability Laboratory (UNH-IOL) iSCSI, Fibre Channel, SAS and SATA consortiums, interviewed Mike Fitzpatrick of Fujitsu Computer Products of America, to learn how the company approaches testing Serial Attached SCSI (SAS) hard disk drives. Fitzpatrick was interviewed during a recent SAS interoperability plugfest held at UNH-IOL that drew 17 companies. Fujitsu and UNH-IOL are members of the SCSI Trade Association (STA).

Author: Don Harbin
Intel Corporation

As the limits of technology have pushed the traditional parallel bus technology toward serial technologies, it makes sense that this phenomenon should occur on both sides of an I/O controller. And this indeed is what is occurring with the onset of PCI Express (PCIe). This article will discuss how I/O controllers are advancing and how PCIe will be utilized to meet the performance demands of the future.

In order to attain higher speed data buses, designs have moved from the traditional parallel bus technologies to serial-based technologies, which employ features such as differential pair transmit / receive data lines. The entry of serial technologies such as Serial ATA, Serial Attached SCSI (SAS) and PCIe, are displacing Parallel IDE, Parallel SCSI and PCI-X in turn.

Author: Dennis Alexander
Hewlett-Packard

Although the design of a Serial Attached SCSI (SAS) backplane is not a trivial matter, the design task is much simpler than the design and layout of a parallel SCSI backplane. A parallel SCSI backplane has 27 differential signaling pairs that must be routed in a daisy-chain fashion from the I/O connector to each of the disk drive connectors that reside on a common SCSI bus. SAS is a point-to-point interconnect comprised of only two differential signaling pairs per drive (transmit and receive) that are routed between the I/O connector and each disk drive connector. Four signaling pairs are required for each drive if dual-port operation is supported.

Parallel SCSI drive backplane connectors also have four SCSI ID pins per drive that must be connected and six single-ended signal pins per drive that can optionally be used. SAS has one single-ended signal that may be used to indicate drive ready status, but no SCSI ID pins.

Power and ground connections are basically equivalent in design complexity for the two protocols, however SAS has an optional +3.3 volt supply input to support future SAS drives that may require 3.3 volts.

The SAS protocol allows SAS backplanes to support Serial ATA (STA) disk drives. Parallel SCSI backplanes can only support parallel SCSI devices.

Author: Mike Micheletti, Product Manager
Computer Access Technology Corporation (CATC)

Serial Attached SCSI (SAS) has moved quickly from lab prototypes to early silicon because its designers deliberately limited the amount of new technology in the specification. Its physical layer is leveraged from Serial ATA and the SAS link layer borrows liberally from Fibre Channel for encoding, addressing and transport.

By borrowing technology from field-proven protocols, SAS can minimize interoperability problems and accelerate its introduction. As with any new storage technology, SAS must deliver state-of-the-art reliability to be successful. Most system integrators agree that signal integrity and fault handling logic will need careful validation before SAS can meet a broad range of enterprise-worthy applications.

Author: Marty Czekalski
Maxtor Corporation

When introducing a new interface into a system, several questions generally come to mind such as; what characteristics does the new device possess, what are its specifications and how will it fit into the overall system design?

This development overview article will look at devices that can be used in Serial Attached SCSI (SAS) systems. We will also look at some of these devices' characteristics and how various standards organizations and committees manage their specifications. Finally, we will talk about where a designer or technical professional can go to get additional information on various components. (For the purposes of this article we will focus primarily on SAS disk drives and will briefly discuss tape drives and Serial ATA (SATA) disk drives.)

Author: Paul Griffith
Adaptec

SCSI is the most versatile disk interface used today for mass storage in enterprise environments by virtue of the protocol's advanced features, throughput capabilities, and support for large storage infrastructures. But the growing need for faster, more complex data communications and more scalable storage systems raises the question of whether parallel SCSI can support the increasing capacity scalability requirements needed for external storage systems.

The physical layer of the parallel SCSI bus has continued to limit its ability to widely scale. While standard unassisted Low Voltage Differential (LVD) SCSI supports a maximum of 12 meters between the computer and external device, many of today's larger SCSI systems require cables longer than 12 meters; hence, the need for SCSI bus expanders.

Author: James Pascoe
Hitachi GST

Hitachi recently interviewed David Steele, Director of Product Planning and Management for Storage Standard Products in the Storage Components Division of LSI Logic Corporation. LSI Logic is a leading designer and manufacturer of storage, communications and consumer semiconductors for applications that access, interconnect and store data, voice and video.

Steele has more than 20 years of experience in the semiconductor industry and is currently responsible for defining roadmaps for LSI Logic's storage standard product IC's, including SCSI, SAS and Fibre Channel solutions. Hitachi asked Steele what IT departments should consider as they prepare to deploy SAS-based storage, including issues such as ease-of-use and management, interface performance, investment protection, etc.

PMC-Sierra was interviewed by a System Integrator about Serial Attached SCSI's Cable and Connector Features and Uses

Author: Rachelle Trent, Product Marketing Manager
PMC-Sierra
All Figures are courtesy of Molex

The challenges that System Integrators (SIs) encounter when learning how to handle new technologies, new components and especially how to make everything work together, requires research and experience. It helps them acquire the knowledge they need if they have a series of demonstrations of cables and connectors and their uses. The purpose of this article is to provide a mini-demo through the use of illustrations that are clear and easy to understand.

Author: Paul Griffith
Adaptec

Introduction
Today, most data centers use parallel storage technology like SCSI, but as requirements for increased performance, higher scalability and improved reliability grow, IT managers are looking to new serial technologies such as Serial Attached SCSI. IT managers needing a simple, cost-effective way to migrate from parallel-technology to serial-based systems with minimal disruption to business operations will find direct-attach storage (DAS) spillover, adaptive storage migration, and DAS evacuation powerful tools for enabling this transition.

Author: Marty Czekalski
Maxtor Corporation

With Serial Attached SCSI--Everyone Wins
In this day and age, where technologies come and go, it's unusual to find a case where change has benefits across the entire supply chain, from manufacturer to end user. All too often change is made to benefit only a small segment of this chain, to push the performance envelope, or just for the sake of change itself. With Serial Attached SCSI (SAS) there are benefits for everyone involved in bringing this technology to market. In this article we'll explore the various aspects of one such benefit, investment protection.

Author: Harry Mason
LSI Logic

Serial Attached SCSI (SAS), much like legacy SCSI, is architected with the following components:

• Host Controller:
  • ChipBoard
  • RAID
• Expanders
  • Edge Expanders
  • Fan-out Expanders
• Interconnection schemes
  • Connectors
  • Cables
  • Backplanes
• Storage Devices
  • Disk Drives
  • Tape Drives
  • SATA Drives
• Text/Validation Systems

Author: Bob Sheffield
Intel Corporation

Serial Attached SCSI (SAS) extends the SCSI roadmap well beyond the limitations of parallel busses. Parallel SCSI has achieved geometric improvement over the last 20 years by doubling the bandwidth in each subsequent generation: from 8 MB/s (megabytes per second) to 320MB/s over its lifetime. SAS’s link rate of 3Gb/s (gigabits per second), delivers 300MB/s if accounting for 8b/10b encoding. SAS is 20 MB/s slower than parallel SCSI point to point, often creating confusion about which interface is faster. This article evaluates three key features of SAS which provide performance and scaling well beyond parallel SCSI:

• Full duplex
• Switched transport
• Wide ports

Author: Tom Robinson
I-TECH Corp.

If developers and manufacturers of products for storage infrastructure are considered to be on the leading edge of new storage technologies, test equipment vendors can be considered to be on the “leading edge of the leading edge.” And the latest leading edge is a significant shift from parallel to serial technologies.

The evolution of parallel SCSI interface test equipment was relatively straightforward through the introduction of Ultra320 SCSI in which electrical performance limitations resulted in cross-talk, low-level ground noise, and signal skew. This new generation of SCSI, Serial Attached SCSI (SAS), specifies the established SCSI protocol as a new gigabit serial technology.

Seagate Technology recently met with storage architect from a Fortune 500 Company located in St. Paul, Minnesota to get his insights on the issues surrounding migration from parallel SCSI to Serial Attached SCSI (SAS). In the following interview, our storage architect shares his views on why moving to SAS will ensure the flexibility needed to meet the storage challenges of today and tomorrow.

Author: Marty Czekalski
Maxtor Corporation

Years ago, nearly all interfaces were serial. Communications, printers, and disks all used serial interfaces. Those were the days of discrete components, and reducing the component count was an important factor in keeping costs under control. As the level of integration increased, it became possible to put multiple drivers on the same piece of silicon as the logic. This made parallel interfaces both high-performance and cost-effective. As a result, parallel interfaces became the rule and serial interfaces the exception, except in long-distance communications, where the cost of the high-speed transmitter/receiver technology was offset by the savings in wire (or fibre) costs.

Interestingly, as technology has moved forward, the same advances in integration that caused parallel interfaces to gain favor are now working against them. The I/O cells are not scaling at the same rate as internal logic, and it is now easier and less costly to add sophisticated signal processing at lower cost than adding additional I/O cells needed by parallel interfaces. The result is that these high-performance serial interfaces are becoming cost effective at shorter and shorter transmission distances as the levels of integration increase. We now find ourselves switching back to serial interfaces such as USB for printers and PCI Express for PCI replacement. The next step will see this same migration in the interfaces we use to connect disk drives. The evolution of ATA and SCSI will move these interfaces to Serial ATA and Serial Attached SCSI. This article will explore some of the details driving this transition as well as the advantages of these serial topologies.

By LSI Logic

Today’s enterprise storage landscape is dominated by products using the SCSI interface. With close to 90 percent market share of all enterprise-class storage systems, SCSI is clearly the most widely deployed, high-availability enterprise storage I/O technology in use. Over its twenty-year history SCSI has evolved dramatically, currently offering a parallel interface that supports data rates of up to 320 Mbytes/sec. Throughout those two decades SCSI has remained a compelling interface, to system designers and IT professionals alike, because it offers three critical advantages: high performance, exceptional flexibility with the ability to connect to multiple peripherals, and proven backward compatibility.

As with the introduction of any new technology, the migration from parallel SCSI to Serial Attached SCSI (SAS) requires OEMs give due consideration to the implementation, deployment, and maintenance of new SAS-based solutions. That said, transitioning from a parallel architecture to a serial, point-to-point model may prove less daunting than some expect, while providing investment protection well into the future.

Adaptec recently met with a group of Value-Added Resellers (VARs) to get their insights into today’s storage market. Representing one of those VARs was Vince Conroy, Chief Technology Officer of NACIO Systems, a full-service provider of managed hosting, storage and connectivity solutions for businesses that rely on the Internet for daily operations. In the following interview Mr. Conroy shares his views on how Serial Attached SCSI (SAS) will help his customers protect their storage investments.

PMC-Sierra recently had the opportunity to interview Tim Symons, Storage Architect & Technologist in the Storage Solutions Group at Adaptec, to discuss Serial Attached SCSI (SAS) and how customers will make the transition from parallel SCSI to SAS. Adaptec offers direct-attached and networked data storage for mission-critical applications, from data warehousing and transaction processing to streaming video, medical imaging, digital pre-press and more.

Never before has the enterprise enjoyed such a broad variety of storage solutions from which to choose. Innovative new offerings in both hardware and software seem to appear almost daily, promising unprecedented flexibility to specify the most appropriate, targeted solution for any storage challenge.

By: Hitachi Global Storage Technologies

The ATA and SCSI hard drive interfaces that are commonly associated with desktop and enterprise storage applications are examples of parallel bus architectures. These architectures will eventually transition to serial implementations to improve data signal integrity, enable smaller designs and overcome the bandwidth limitations of their predecessors. The new serial interfaces--Serial ATA (SATA) for PCs and workstations and Serial Attached SCSI (SAS) for mission-critical computing--have also been designed to improve performance, reliability and scalability. There are several attributes that combine to substantially reduce the total cost of ownership for desktop and enterprise storage.

These emerging interface standards offer investment protection as a result of the following: configuration flexibility, backward compatibility and a performance roadmap extending out nearly a decade. Let's look at each of the characteristics in greater detail:

By: HP

Today's companies have limited flexibility when choosing a data center storage solution. Their options have been restricted to separate systems based on ATA, SCSI, or Fibre Channel disk interfaces. These storage options inhibit the IT manager's ability to deploy and redeploy core technologies, thereby adding significant cost and management burden to the enterprise. With the advent of serial I/O architectures, key solution providers can now provide one system or storage solution that will meet the requirements of a broad range of storage applications, while at the same time reducing total cost of ownership. This will enable IT managers to standardize on a single server or storage platform, which can dramatically reduce the cost and complexity of managing the wide variety of storage applications in today's data center.

Serial Attached SCSI (SAS) technology empowers customers to deploy a standardized server product while providing the flexibility to "customize" storage. Low-cost Serial ATA (SATA) disks will be ideal for near-line applications, while SAS disk performance and uptime requirements will meet the needs of mainstream server and storage applications. Users may decide to deploy a single model of server or storage enclosure across the enterprise, and then customize the hard drives based on the individual requirements--another key benefit of this serialized architecture and its ability to lower the total cost of ownership.

Author: Debika Ingham
Intel Corporation

With the advent of any new interface, users of the technology invariably ask, "Now what do I have to buy?" And perhaps more importantly, "What existing investments have been protected?" The transition to Serial Attached SCSI (SAS) will ensure many levels of investment protection, both during its initial stages and long thereafter.

Chaparral Network Storage designs and markets storage appliances that provide simple solutions to common storage networking problems. Chaparral specializes in advanced performance devices that deliver data efficiently within the network, and sells protocol bridges, data routers, RAID controllers and disk array appliances that are network-ready. Maxtor recently had the opportunity to sit down with James Russo, Vice President of Engineering, at Chaparral Network Storage to discuss his views on Serial Attached SCSI (SAS), and how its ability to interoperate with Serial ATA (SATA) disk drives will affect the way storage systems are designed and deployed.

Author: Paul Griffith
Adaptec, Inc.

Today’s system builders must develop, test, qualify, inventory and sell separate subsystem backplanes to meet their customers’ needs for storage of reference and transactional data. Distributors and IT managers must also deal with the inefficiencies of separate systems. Serial Attached SCSI (SAS) will enable computer makers to build a single system that supports disk drives for both data types, reducing development costs. For customers, standardizing on one server and storage infrastructure will increase storage flexibility and reduce total ownership costs.

Author: Michael Micheletti, Product Manager, LeCroy Corp.

Serial Attached SCSI (SAS) is a storage interface developed to meet the needs of enterprise-class storage applications. Leading solution vendors are rapidly adopting this new standard because it offers superior performance while preserving compatibility with legacy SCSI applications. Central to the SAS value proposition is its ability to scale storage systems beyond the limits of today’s parallel SCSI by using a switching technology called expanders. Designed to provide a fan-out architecture for SAS, expanders allow SAS initiators to connect up to 16,000 physical links per domain. Yet this is only one aspect of SAS' scalability as an enterprise-class storage interface.

Another important advantage of SAS is interoperability with Serial ATA (SATA) disk drives. The SAS specification defines an electrical and physical connection interface within the backplane that is form-factor compatible with SATA. This feature is ushering in a new approach to storage system design, enabling manufacturers, integrators and users to populate a single storage enclosure with either SAS or SATA disks. Enterprise-class storage systems can be equipped with high performance SAS drives for mission-critical applications. The same storage enclosure can also be introduced with lower cost SATA drives to address segments of the market that value capacity over performance.

Jim Pascoe
Hitachi Global Storage Technologies

Use of the parallel bus interface, which has long been the industry-standard storage interconnect, is on the verge of decline among the vast majority of system builders. Components that are based on the aging interface are increasingly being replaced by their evolved serial counterparts—Serial Attached SCSI (SAS) and Serial ATA (SATA).

The new serial interfaces are designed to address the bandwidth limitations of their predecessors. They will support faster data transfer rates and more devices per controller, as well as reduce the size and complexity of the cables and connectors (thus enabling smaller, more densely-packed disk arrays). Among the most significant benefits is that incompatibility between SCSI and ATA will finally be addressed.

Authors: Franco Castaldini & Kent Bransford
Seagate Technology

The advent of Serial Attached SCSI coincides with a fundamental change in enterprise data management. Gone are the days when there were only two types of data storage: online and offline. A new concept, near-line or secondary storage, quickly gained acceptance because it recognizes that data has a lifecycle, during which its need for accessibility and security will vary. Rather than a simple online/offline dichotomy, enterprise storage now comprises a continuum along which data can easily migrate as its value and relevance change.

Author: Harry Mason
LSI Logic Corporation

While storage consumption continues to grow at a phenomenal pace, spending on Information Technology (IT) has been, and is projected to be, flat to slow when viewed in the aggregate. This low-growth environment drives the market to seek more efficient ways to accommodate the unabated creation of more and more data. In order to manage this torrent of stored data, concepts like Information Lifecycle Management (ILM) have emerged. This and other innovative concepts enable suppliers and end users to more efficiently provision tiered pools of storage in the face of constrained IT spending.

With the complex demands being placed on data, demands that vary throughout the data’s lifecycle, it’s doubtful a single disk drive can ever service the entire range of market needs. It seems the market will always be bifurcated by its demand for drives that both target the enterprise’s need for performance and high availability, and desktop-class deployments that emphasize cost and capacity.

Serial Attached SCSI (SAS) is the first and only data storage connection scheme that resolves these conflicting data center needs. Never before has the market been able to use a single connection scheme to support both enterprise- and desktop-class drives. This common infrastructure can be used to service a broad range of market needs, while also enabling IT resources to be dynamically re-purposed to meet the changing demands on data throughout its lifecycle.

Serial Attached SCSI (SAS), the next generation SCSI standard, provides IT implementers with maximum flexibility in configuring their storage environments. SAS supports logical compatibility with Serial ATA (SATA), enabling one storage design to service both high performance mission-critical storage (SAS) and low cost bulk storage (SATA).

PMC-Sierra recently spoke with members of IT departments at medical imaging, software development and financial companies to discuss their current storage strategies and their thoughts on the benefits that SAS can provide. Their responses (summarized below) highlight the exceptional flexibility and cost-effectiveness that SAS/SATA compatibility can bring to the enterprise.

Author: Tonya Comer
HP

Current server solutions lack flexibility in the type of storage they deploy. Systems designers for direct attached storage (DAS) must choose between a low cost storage interconnect like Serial ATA, a mainstream interconnect like U320 SCSI or a high-end interconnect like Fibre Channel. The interface decision dictates the remaining storage infrastructure costs, limiting users’ ability to deploy and redeploy core technologies, and potentially adding significant expense and management burden to the enterprise.