STA

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.