By Dave Simpson
Emulex is spearheading a potential standard, recently dubbed “FC-SATA,” that is analogous to Serial Attached SCSI (SAS): Just as SAS subsystems can accommodate both SAS and Serial ATA (SATA) disk drives, FC-SATA arrays would be able to accommodate both Fibre Channel and SATA drives. The potential advantages are increased flexibility for OEMs, systems/storage integrators, and end users, as well as lower costs and the ability to create “in-the-box” tiered storage with low-cost SATA drives and high-performance Fibre Channel drives. For example, Fibre Channel drives could be dedicated to online data processing applications while SATA drives are used for “nearline” data retention and other applications that require high capacity but not the highest performance.
The FC-SATA spec enables native connection of SATA drives to Fibre Channel infrastructures, thereby eliminating the need for costly bridges that convert between the Fibre Channel and SATA protocols. Emulex officials say that bridges can add $400 to $500 to the cost of a disk subsystem. FC-SATA technology would also offer an alternative to SAS subsystems.
The degree to which FC-SATA will succeed may be more a question of timing than technology. Emulex and other vendors have already demonstrated FC-SATA systems at both Storage Networking World conferences last year, but it will be awhile until FC-SATA sub-systems make their way to end users.
Last June, the ANSI T11 standards committee “approved for technical standards development” the FC-SATA spec, which was originally referred to as “SATA Tunneling over Fibre Channel.” FC-SATA is expected to be included in ANSI’s Fibre Channel standard.
Although it’s guesswork at this point, approval of the FC-SATA standard by the ANSI T11 group is slated for April 2007, which means that disk arrays based on FC-SATA are unlikely to ship prior to that date. Although by that time SAS will be well-established, some independent analysts think that there will still be a need for FC-SATA arrays.
“Fibre Channel supporters want to be on equal footing with SAS in terms of incorporating SATA as seamlessly as possible,” says Arun Taneja, founder and consulting analyst with the Taneja Group. “Without the FC-SATA spec, SAS would have an advantage cost-wise and simplicity-wise.
“I do think that Fibre Channel proponents should have responded sooner, but I don’t think it’s too late,” adds Taneja. “Fibre Channel is the incumbent, and no one is going to throw out Fibre Channel at the high-end. It’s in the midrange that Fibre Channel will have to duke it out with SAS. Both Fibre Channel and SAS will prevail, although SAS will put pressure on Fibre Channel margins.”
In the case of Emulex, FC-SATA technology will be enabled by the next generation of the company’s InSpeed embedded Fibre Channel switches. (Emulex claims to have shipped more than eight million InSpeed Fibre Channel ports to OEMs such as Apple, Engenio, Fujitsu, Hewlett-Packard, IBM, NCR Teradata, NEC, Network Appliance, Quantum, Sepaton, SGI, StorageTek, Sun, and Xyratex.) FC-SATA technology could also be implemented in I/O controller chips from other vendors.
For more information on FC-SATA, visit www.emulex.com/fcsata. For more information on the relative positioning of the various disk drive/array interfaces, see the Special Report, p. 22, as well as “SATA, SAS drive toward the enterprise,” InfoStor, November 2005, p. 22.