Seagate touts SAS drives as faster alternative to SATA

While much of the country is celebrating Presidents Day by taking the day off, Seagate Technology LLC is preparing to launch a new disk drive interface. The company will demonstrate its 2.5-inch drive at the Intel Developer Forum in San Francisco this Tuesday.

Small, fast and about the size of a Palm Pilot, Seagate's Savvio serial-attached SCSI (SAS) drives use a full duplex, point-to-point architecture and command queuing to achieve data transfer rates of 3 Gbps.

Serial ATA (SATA) drives are cheaper, but disk makers say that they are also less reliable and slower than SAS and Fibre Channel drives. Scotts Valley, Calif.-based Seagate says that SAS, which was designed as a replacement for SCSI drive technology, saves money by "preserving IT investments" in storage management and enterprise application software. It does this by integrating the same SCSI commands that support enterprise storage environments and eliminating any need for system-level workarounds, like those required for ATA.

Marc Farley, president of Building Storage Inc. and a SearchStorage.com expert, says SAS is a necessary interface because the up-and-coming SATA interface is insufficient for enterprise applications. He said that the SATA interface doesn't provide for command queuing, a function that optimizes the physical movement of the drive arm. SATA also comes up short in the I/O department.

"Serial ATA doesn't allow for I/O overlap," he said. "In any multi-program environment, serial ATA doesn't work."

But if drive makers like Seagate and Maxtor Corp. added command queuing to SATA drives, it would change everything, he said.

"There is no reason a serial ATA drive could not be manufactured that would be almost as fast as a 15,000 rpm serial-attached SCSI drive," Farley said. Farley said Western Digital Corp. is going to push the envelope on SATA, while Seagate and Maxtor are going to say SATA is just for desktops. "You can make SATA drives with 10,000 RPM capability," Farley said. "Everyone could crank out SATA drives."

According to Farley, another reason SAS is being heralded as the latest, greatest drive technology is that Seagate and Maxtor both have high profit margins in the Fibre Channel- and SCSI-drive businesses and don't want to see those margins eroded by a desktop drive like SATA.

So what can you do to plan for the drives of the future? While the vendors sort it out, Farley said, users should start familiarizing themselves with the technology, since SATA drives are now available and SAS drives will soon follow.

"It's always a good idea to get a little 'hands-on' with new technology and see what it's like. Stay on top of it," he said.

Gary Gentry, vice president of marketing and planning at Seagate, said the company plans to deliver its first SAS products in fall 2004, and the drives should be turning up in high-performance storage arrays, servers and blade servers soon after.

Let us know what you think about the story; e-mail: Kevin Komiega, news editor.

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