SATA Saturates SANs

If there were any doubts that Serial ATA (SATA) drives have secured a place in SANs, they were eliminated this week.

Just about all the major SAN system vendors have SATA offerings, or will soon, as the following sequence of events indicates:

Peter Herz, who founded SATA controller startup 3ware, which was bought by Applied Micro Circuits Corp. (AMCC) (Nasdaq: AMCC) in March, attributes the rise of SATA to the successes enjoyed by EMC and Network Appliance Inc. (Nasdaq: NTAP) in the market for ATA, the technology's parallel predecessor. As a result of those companies legitimizing the technology as more than just a way to sell cheap disk, years of resistance to ATA technology has fallen away.

"I think we've hit the tipping point," Herz says.Now that the market has a slew of new SATA products, the question is how the low-cost, low-performance drives will be used. EMC and Dell aim their wares as primary storage for small companies. The others say SATA is suited for secondary or backup storage, although there is hedging on this.

For instance, IBM positions the FastT 100 as a secondary storage system. And while Engenio director of product marketing Steve Gardner says the system his company sells to IBM could be used for primary storage, he doesn't recommend it.

"SMB users might consider this primary SAN storage," Gardner says. "You could use it for that, but it's certainly not going to offer high performance for IOPS [input/output operations per second]."

Though SATA drives perform better than ATA, Gardner says testing shows SATA drives have about one-fourth of the IOPS performance of Fibre Channel drives. So, while Fibre Channel is better for transaction-heavy applications, SATA has a place in video, medical imaging, surveillance, and high-performance computing environments, where backup is crucial but not associated with live transaction processing.

Sun director of technical marketing Chris Wood says SATA arrays are built for low-duty cycles used in secondary storage. "It's inappropriate to sell it any other way, based on design," he says. "If you use it at a 100 percent duty cycle, you will be disappointed."Herz says all drives fail, not just SATA drives. The issue is whether a company can live with more frequent failures, which means rebuilding drives while using a replacement.

Gardner says users will be the ultimate judges. "In the end, the market will decide," he says. "In six months, we'll all have a beer and talk about it."

By then, we'll be wondering about the effect Serial Attached SCSI (SAS) will have on SANs and SATA: SAS drives are expected late this year. Then there are other options, such as the FATA (Fibre Attached Technology Adapted) drives offered by HP, as well as combination systems that bridge Fibre Channel to SATA such as Digi-Data's (see EMC and HP Spin Disk).

"There's a lot of confusion about drives," Gardner says. "People look at SAS, SATA, FATA, and they're trying to figure out the right combination of interfaces."

Herz says he thinks SATA will win a spot in the low end, while SAS and Fibre Channel share the high end. "I think it is going to confuse people, but the real battle is between Fibre Channel and SAS," he says. "SATA sells to a different customer."— Dave Raffo, Senior Editor, Byte and Switch