SAS Wave Breaks Big

Check the storage headlines, and you'll find a lot of "SAS." Serial-attached SCSI products, hyped a couple of years ago as a performance challenger to Fibre Channel with the lower-cost profile of SATA, are finally taking off.

Recent announcements include SAS controllers from Adaptec, AMCC, Atto, and LSI; arrays from Infortrend and Promise; and test equipment from Finisar and LeCroy. (See Adaptec Makes Announcements, ATTO Intros RAID Adapters, LSI Offers Adapters, Infortrend Ships Array, Promise Unveils Products, Finisar Debuts Analyzer, and LeCroy Unveils Analyzer.)

The news follows support of SAS from major vendors, including IBM and HP, late last year, as well as Data Domain via Xyratex componentry more recently. (See IBM Turns to LSI for SAS and Data Domain Taps Xyratex.)

"This pickup in SAS activity is just the start of a sustained ramp-up of the SAS ecosystem over the next several years," states Greg Schulz of the StorageIO Group. He notes that benefits of performance and reliability similar to Fibre Channel, along with features like native dual-port capability, are moving SAS to the forefront of storage demand.

One user, for instance, has deployed SAS drives in EqualLogic's iSCSI storage arrays to activate a new tier of online database processing. "The random data loads from our mobile business services running on Oracle created a serious need for high-performance storage," said Andy Monroe, VP of technology at mobile information services firm AirClic, in a prepared statement. "When we wanted to replace our direct-attached storage, the common misconception was that Fibre Channel was the only choice for performance. But when we ran our high-transaction databases on EqualLogic's new SAS-based array alongside Fibre Channel products from large vendors, the performance... was superior."Demand for similar tiered storage setups may be imminent. In a recent Heavy Reading survey, 81 percent of 136 IT managers listed database processing, after backup, as the second chief application for deploying SANs. (See Survey: SAN Extension on the Rise.)

If it's so great, why has SAS taken so long to roll out in any meaningful way? The key holdup has been compatibility with SATA. "SAS was supposed to be here a year ago. Frankly, I'm not surprised," says Arun Taneja of the Taneja Group consultancy. While SAS and SATA were supposed to be compatible, he says, it took a lot longer than expected to actually make them work together. (See IBM Turns to LSI for SAS.)

But joint SAS/SATA support is key to the value of a SAS system, particularly for OEMs. "Both SAS and SATA devices can coexist on the same adapter and controller port, bringing economies of scale over time for vendors and customers alike," Schulz maintains.

Besides SAS/SATA support, Schulz and others make these recommendations to prospective SAS buyers that gear include these features:

As the SAS train leaves the station, a couple of vendors remain behind. These include EMC and Network Appliance."We do not believe the technology is mature enough yet for a premium class of storage array like the Clariion CX3 series," writes EMC spokesman Rick Lacroix in an email to Byte and Switch. "We feel there is some maturing of the technology from an availability/reliability/economics perspective that needs to happen in order for us to offer it." He notes that SAS was originally aimed at replacing parallel SCSI as the link to internal storage in servers.

Likewise, here's what NetApp spokesman Craig Pratt has to say: "NetApp is following this space closely and waiting for additional maturity in SAS silicon infrastructure. With the challenges the industry is having with SAS technology, we just don't think the current risk level is appropriate for our customers. We will keep you posted as we monitor evolution in this area."

Notably, though, NetApp execs refused to comment during their analyst day this week about word of a pending low-end SAS product, which originally was said to be based on an OEM deal with Dot Hill. (See NetApp Stokes Competitive Fires.)

Mary Jander, Site Editor, Byte and Switch