The other fast storage

ALTHOUGH MOST OF the buzz surrounds SCSI and Fibre Channel devices, a new category of storage devices has been quietly evolving. We are talking about SATA (serial ATA), the natural, backward-compatible result of steady advancements in the technology that gave us the low-cost, high-performance ATA drives in most desktop PCs, entry-level servers, and NAS appliances.

Just to refresh your memory, the ATA parallel interface topped its performance limits at 133MBps, whereas SATA promises a smooth ride from the 150MBps throughput of its initial implementation to rates as fast as 600MBps. In addition, moving from a parallel interface to a serial interface spurred a significant improvement of the physical interface -- that is to say, the connectors and cables -- of the drive.

Doesn't sound like a big deal? Consider that recent CPUs and disk drives generate an incredible amount of heat, requiring adequate air flow inside the computer case to keep things cool. The ATA interface, with its flat, short, and wide ribbons, creates challenging ventilation problems. By contrast, SATA's longer, pencil-thin cables, smaller connectors, and low-voltage signals are a blessing for computer and storage-device manufacturers who are investing significant R&D dollars in this technology.

But can SATA compete outside the ATA niche, against technologies such as SCSI and Fibre Channel, which offer better performance and can stretch beyond computer-case boundaries?

An apples-to-apples comparison between technologies as diverse as SATA and SCSI is not possible. But SATA devices are expected to maintain a street price not much higher than their predecessors. In addition, consider that the per-gigabyte cost of current SCSI drives is at least four times that of ATA drives. Native Fibre Channel drives are even more expensive.

This will likely result in more OEMs switching from SCSI to SATA to build systems more easily and more cost-effectively. Furthermore, SATA's point-to-point connection requires a switched bus architecture, and that's sweet music to the ears of vendors such as 3Ware who have been trumpeting the advantages of a switched architecture over SCSI, in which devices are daisy-chained and share bus capacity.

With that in mind, it's fair to assume that bottom-line considerations will prompt enterprises to set aside a significant portion of their storage budgets for SATA solutions.

And before they know it, enterprises will have SATA products to purchase. Later this month, 3Ware will release a SATA RAID controller card. And this fall, Seagate will begin shipping a Baracuda drive with the SATA interface. Seagate imagines SATA working well in entry-level servers and high-end workstations and has every intention to gradually phase out ATA.