Servers Get Some SAS

HP and IBM, among others, plan to expand the use of serial-attached SCSI drives in their servers.

Corporate IT users this year will see a host of servers come on the market with new hard drives that promise better performance and power efficiency, helping to address two of the bigger concerns on the minds of data center managers.

Some OEMs, including Hewlett-Packard Co. and IBM, have been sprinkling the SAS (serial-attached SCSI) drives into select servers over the past year but are promising to outfit more of their systems with the new drives this year. Others, such as Gateway Inc. and MPC Computers, plan to bring the SAS drives into their server portfolios this year.

The new drives, from makers such as Seagate Technology LLC and Adaptec Inc., offer faster performance than their parallel SCSI and SATA (Serial ATA) brethren. They come in 3.5-inch and 2.5-inch models, with the latter being easily installed in smaller form factors such as blade servers. The smaller size also enables server makers to put more drives into a system to improve overall performance and consume less energy, as well as allow better airflow for enhanced power efficiency and cooling.

/zimages/4/28571.gifClick here to read more about Adaptecs SAS drives.

The ever-increasing amount of heat generated by todays powerful servers is one of the key problems facing enterprise IT shops. As businesses look to save money through server consolidation projects, they often end up bringing in machines with more drives per box, which draw more power, generate more heat and increase cooling costs. The forthcoming SAS drives are designed to meet these challenges head-on.

The serial nature of the drives also moves away from the slower shared bus architecture in the parallel SCSI drive, and the compatibility with SATA drives enables users to adopt the SAS technology as desired. "Its the same type of technology, now just on steroids," said Alex Smith, director of the enterprise product group for MPC, of Nampa, Idaho.

"[The use of SAS by systems makers] is pretty limited right now," said Dave Reinsel, an analyst with IDC, in Hutchinson, Minn. "2006 will be a good year. Its a huge factor for systems OEMs because faster drives are something theyre trying to work into their systems."

IDC sees a healthy market for SAS drives. Last year, 1.5 million SAS drives were shipped—a fraction of the overall 32 million drives sold. In 2009, IDC expects that about 20 million of the 54 million drives shipped will be SAS.

The speed of the drives—at 10,000 rpm to 15,000 rpm, faster than the 7,200 rpm of many SATA drives—is a key feature. SATAs current theoretical limit of 150MB per second will improve to 300MB per second when the interface goes bidirectional this year. The bidirectional SAS currently tops out at 600MB per second.

It was speed that Starz Entertainment Group LLC needed. SEG is using Opteron-based HP ProLiant DL385 and DL585 servers armed with 2.5-inch SAS drives in an internal project. The Englewood, Colo., company is taking hundreds of hours of video content out of a SAN (storage area network) library and running the content through the servers before playing it back, said Stephen Smith, manager of automation and system integration at SEG. Doing so enables the content to be cached locally on the SAS drive, protecting it in the event of a SAN failure. To do this, SEG needed to find a technology that could move the content quickly from the SAN to the server for caching.

"The bottom line is, this is pushing the content into the server very quickly and pulling it out as well," Smith said. "The alternative would have been going with [parallel] SCSI drives, but we needed something small that could go into the servers."

David Lawler, director of product definition and strategy for Sun Microsystems Inc.s Network Systems Group, said the vendors "Galaxy" systems—powered by Advanced Micro Devices Inc.s Opteron chips—and the new servers using Suns UltraSPARC T1 processors both were designed with speed and power efficiency in mind. It made sense to put SAS drives in both product lines, and the Santa Clara, Calif., company will continue to roll out systems with the drives in the future. "It is the future," Lawler said. "There are significant advantages over parallel SCSI. Sun is committed to SAS. We want to maximize overall performance and lower power consumption."

The cooling issue is important as processors get more powerful and servers get smaller, said Jay Bretzmann, director of IBMs xSeries high-performance server division. Having the smaller drives enables an enterprise to add more performance without having to increase its data center cooling budget. IBM, of Armonk, N.Y., has put SAS drives into several Intel Corp.-processor-based xSeries systems, including the 3U (5.25-inch) x366. IBM put the 2.5-inch drive into the system even though at 10,000 rpm it was slower than the 3.5-inch 15,000-rpm drive. It was either that or grow the server to 4U (7 inches). "The adoption of the 2.5-inch [drive] was necessitated by cooling," Bretzmann said.

The expected development of 2.5-inch drives that run at 15,000 rpm will further drive adoption, he said. Still, the current 2.5-inch drives offer significant benefits, said Paul Perez, vice president of storage, networking and infrastructure for ProLiant servers at HP, in Palo Alto, Calif. OEMs can put one-third to one-half more drives into standard enclosures.

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