STA

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: 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; 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.

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.

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: 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.

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: Chris Croteau
Intel Corporation

SCSI is undergoing an exciting serial transformation, one that goes far beyond a mere parallel-to-serial conversion to deliver significantly increased capabilities. Serial Attached SCSI (SAS) is the next evolution of SCSI technology following Ultra320 SCSI, utilizing a speedy serial point-to-point architecture to eliminate the bus overhead of today’s parallel SCSI technology. Dual-ported devices are also a standard feature for Serial Attached SCSI, enabling multiple signal paths for each disk drive. In addition, Serial Attached SCSI will have the ability to scale to over 16,000 physical devices in a single domain through the use of expanders. And SAS leverages existing SCSI protocols, thus ensuring backward compatibility with legacy SCSI drivers and enterprise application software.

In addition to compatibility with existing SCSI drivers and software, Serial Attached SCSI offers interoperability with Serial ATA devices. This is an unprecedented development in storage technologies. The inclusion of the Serial ATA Tunneling Protocol (STP) allows Serial Attached SCSI environments to host Serial ATA devices. This will not only allow flexibility in system deployment, but also offers end users more choices based upon economics and workloads for specific applications.

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.