Users, integrators give SATA 'thumbs up'

But reliability concerns remain

By Sonia R. Lelii

Gary Pilafas, manager of enterprise architectures at United Airlines, is one of those users who have the burden of satisfying the numerous legal requirements the government is putting on IT organizations these days. He is finding Serial ATA (SATA) to be a useful technology, especially in the areas of data protection and long-term retention.

Joe Rorke, vice president of Rorke Data, once was a doubter regarding the use of disk arrays based on SATA drives because he did not trust the reliability of those drives. But now he has no reason to shun the interface since his company, a subsidiary of Bell Microproducts, has seen a 300% revenue growth in SATA devices over the last three quarters.

More and more, the Serial ATA interface is starting to make its way into storage configurations, particularly in second-tier applications where data has legal retention and compliance requirements. End users, third-party integrators, and VARs say that SATA technology is having an impact on a variety of storage applications, including low-cost mirroring and disk-to-disk backup.

"SATA is definitely here to stay," says United Airlines' Pilafas. "We have found application environments that are a perfect fit for them."

However, for the most part, users are still wary about using SATA drives in the heart of their data centers for "mission-critical" applications. For example, Pilafas, who is currently testing SATA arrays for specific data-retention applications, says he understands that there are tradeoffs that come with the low price of SATA drives and arrays. "I'm not buying SATA drives for performance and reliability," says Pilafas. "They fail more often [than Fibre Channel or SCSI drives], but I know that."

But Pilafas is willing to use SATA drives for some e-commerce applications, where data can be copied via snapshots and saved for long-term retention.

For instance, every time a United Airlines (UA) business partner changes content for promotional deals on the United.com Website, that change is saved on a file system that needs to hold the information for three years.

"Based on my tests, I really like the SATA drives," Pilafas says. "It's kind of like a big parking lot for data."

Gartner estimates that a total of 26 million multi-user disk drives will be shipped this year. ("Multi-user," or "enterprise-class," drives are tracked separately from "mobile/desktop" drives.) Parallel versions of SCSI are expected to make up 55.6% of the total market, while Fibre Channel drives will account for approximately 27% of the market followed by ATA/SATA at 16.4% and SAS drives (which aren't shipping yet) at about 1% of the total market.

In 2008, the interface scenario will shift dramatically (and the multi-user drive market is expected to exceed 35 million unit shipments). Gartner expects SAS drives to make up 37.9% of the total multi-user market, followed by Fibre Channel at 31.6%, SATA at 30.3%, and parallel SCSI at only 0.2%. (In the mobile/desktop market, SATA is expected to account for virtually 100% of drive shipments by 2008.)

"SATA's encroachment [onto SCSI's territory] is happening faster than Fibre Channel's," says Eric Herzog, VP of marketing and business development for Ario Data Networks. "The biggest loser is [parallel] SCSI, and the winners are SAS, SATA, and Fibre Channel."

Rorke mentions some solutions where SATA is a safe bet. For example, in some instances he has used Maranti's intelligent switches to do low-cost mirroring to SATA arrays, in some cases eliminating the need to purchase expensive enterprise-class disk arrays for mirroring. But, like UA's Pilafas, Rorke notes the reliability issues regarding SATA drives.

"We're using SATA in controlled scenarios," says Rorke. "We're not trying to upstage an EMC Symmetrix [in the data center]. The place for SATA is not in the middle of the data center, but in ancillary roles."

Another SATA solution Rorke mentions involves using Quantum's DX series of disk arrays for tape emulation to reduce backup windows.

Backing up to SATA drives, which look like tape drives to the servers, enables administrators to do backups five times faster than with tape libraries, according to Rorke.

But as an integrator, Rorke still is adamant about not using SATA drives in the heart of a data center. He believes that SATA has a more viable place in second-tier storage applications. "SATA does not belong in a 'five nines' environment," says Rorke.

For more information about Serial ATA, see the following two articles in InfoStor. (Both include detailed projections on shipments of all types of disk drives.)
"SATA blurs the lines between desktop and enterprise," June 2004, p. 20.
"Serial ATA activity heats up," January 2004, p. 1.

For an in-depth look at Serial-Attached SCSI (SAS), see "Tech preview: Serial-Attached SCSI + PCI Express," June 2004, p. 26.

This article was originally published on August 01, 2004