Fixed content adopts SATA

Now that the SATA (Serial ATA) interface has proven its merit with solid industrywide support, storage vendors are turning their attention to the next big thing in disk interface technology, the forthcoming SAS (Serial Attached SCSI) interface. SAS is expected to deliver quicker connectivity, lower implementation costs for storage and server vendors, and dual port capabilities for redundancy. SATA, meanwhile, has carved a valuable niche providing in-line secondary storage.

LSI Logic Inc., Seagate Technology LLC, and Maxtor last week demonstrated LSI Logic's SAS controller and expander executing SCSI write and read commands to Seagate's and Maxtor's SAS disk drives. This first public demo is important from a hardware perspective and will benefit enterprises down the road, said Kevin Gray, business development manager at Maxtor in Milpitas, Calif.

"We're spending a lot of money here and expect product availability in the second half of 2004," Gray said.

SAS, Gray said, is the successor to the SCSI interface found in a majority of servers sold today. Jeff Jenkins, vice president of server storage and infrastructure for HP Industry Standard Servers at Palo Alto, Calif.-based Hewlett-Packard Co., concurs. He estimates that 90 percent of the servers HP sells are SCSI-based and that, over time, SAS will replace the SCSI line of servers, providing even greater benefit and choice because a single SAS controller can control a SAS drive and a SATA drive simultaneously. The first HP servers with SAS drives will be available in late 2004.

SAS's major selling point is the fact that it is a serial technology, meaning it is point to point as opposed to the master/slave architecture of parallel interfaces such as SCSI and ATA. SAS drives are also smaller than SCSI drives and use thinner cables. The same is true of SAS's cousin, SATA, which has shown wide adoption and impact.

In the short time since its inception, the SATA interface has found its niche in disk-to-disk backup products and for storing data that does not reside in a database and change often, such as X-rays, medical records, and legal documents.

A number of companies, including EqualLogic Inc., IBM Corp., and LSI Logic, have already adopted SATA technologies in storage systems, such as Maxtor's MaXLine Plus II hard drives, and many will follow, says Arun Taneja, an analyst at the Taneja Group in Hopkinton, Mass.

He said SATA's affordability and reliability are its key benefits.

"A number of trends are being impacted by SATA," Taneja said. "Data archival backup and restore, disaster recovery, and disk-to disk technologies are all affected by SATA."

EMC introduced its new Clariion line last September, which uses the old ATA drives. According to the company, it is evaluating SATA for its Clariion and Symmetrix platforms.

Also in the market with a solution that uses SATA is EqualLogic and its PeerStorage Array 100E. The ISCSI (Internet SCSI)-based system provides up to 2.5TB per array and houses up to 14 SATA drives.

In May, Milpitas-based LSI Logic began shipping its Serial ATA MegaRAID family of SATA adapter cards. Adaptec Inc., also based in Milpitas, was right behind in June with its controller, Serial ATA RAID 2410SA.

HP's Jenkins said SATA solves many long-standing datacenter problems.

"Cooling and power have long been big concerns of datacenter administrators," Jenkins said. "The thinner cables inside the box don't block air flow."

The smaller disk size also permits more air flow and allows more drives to fit into a single box, he said.

Jenkins agrees with Taneja that reference data is an emerging application that is ideal for SATA. He explains that this fixed content requires low workload because it is not accessed as often as primary data, which often is stored on more expensive and reliable disks such as FC (Fibre Channel).

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