Engenio Technolgies Inc. expects to ship a midrange serial-attached SCSI (SAS)-based storage array as early as 2007, pending a review of SAS drives' reliability, according to president and CEO, Tom Georgens.
At issue is user demand for high-capacity SATA drives used to create a second tier of low-cost capacity in existing midrange arrays. SATA drives can natively plug into a SAS backplane, unlike Fibre Channel (FC) drives.
To put a SATA drive in a FC-based enclosure, you need to use FC-to-SATA protocol conversion hardware. That adds approximately $400 to $500 to a disk shelf, according to Bob Brencic, senior director of switch marketing at FC component maker Emulex Corp.
Furthermore, SAS drives, which will likely replace parallel SCSI disk drives in servers, will ship in greater numbers than FC drives. And unless FC disk-drive vendors significantly reduce their prices, SAS drives promise to be much cheaper.
Should Engenio and other array manufacturers stick to this schedule, users might want to consider whether to purchase SATA-only systems today, or opt to wait for SAS equipment that may have more value in the long run.
FC fights back
To make the switch from FC to SAS enclosures, the array manufacturing empire will have to ditch significant amounts of FC infrastructure, engineering and test equipment. "Why throw out something robust that you have a lot of knowledge about for something that's just full of promises?" Brencic asked.
Reluctant to let that happen, Emulex and FC players Agilent Technologies Inc., Brocade Communications Systems Inc., Hitachi Global Storage Technologies, McData Corp. and Seagate Technology Inc. are working on adding native SATA connectivity to the existing FC protocol (FCP).
Currently a project under ANSI's T11 group, the FC-SATA protocol would simply add the SATA Tunneling Protocol to FCP, just as SAS does today. Brencic expects project members to deliver a first draft of the standard to ANSI in early 2006.