Vitesse Talks Some SAS

Vitesse Semiconductor Corp. (Nasdaq: VTSS) unveiled a series of unusual serial-attached SCSI (SAS) components this week, in a move that could get competitors off the dime (see Vitesse Debuts NexSAS).

SAS is commonly viewed as a replacement for the existing parallel SCSI interface in high-end disk drives and servers used for heavy-duty, transaction-oriented applications. A series of vendors have been eyeing the market for awhile, and some have announced components, including Adaptec Inc. (Nasdaq: ADPT) (see Adaptec Demos SAS Chip); Fujitsu Components America Inc. (FCAI) (see Fujitsu Expands Connector Line); LSI Logic Corp. (NYSE: LSI) (see LSI Logic Intros SAS Controller IC); and PMC-Sierra Inc. (Nasdaq: PMCS) (see PMC-Sierra Chips Into 3-Gig SAS).

Intel Corp. (Nasdaq: INTC) and Emulex Corp. (NYSE: ELX) also announced a joint effort to develop SAS components last year (see Intel, Emulex Join at the Chip). According to Intel spokesman Scott Smith, the joint project is proceeding on schedule: "We're hitting our development milestones and plan to introduce products this year," Smith writes in an email.

Meanwhile, even though many vendors have announced SAS products, the actual roster of what's out there is relatively small, as shown in the table below.

Table 1: Selected SAS Components

Indeed, if Vitesse delivers its new chips on time, it could wind up being first out of the gate to have a so-called expander chip, which acts as a fan-out, creating multiple links from one port -- so that OEMs can link multiple disk drives to a single port on a host adapter, for instance.

Expanders are vital to the emerging SAS market, because some vendors view SAS as a potential aggregator for disk-drive ports. Because the SAS interface can carry tunneled SATA signals, even though SATA can't support tunneled SAS, a SAS expander, on a server, for instance, can be linked to multiple serial ATA (SATA) interfaces on servers, workstations, and direct- or network-attached storage devices.

The availability of a SAS expander could spur more market activity. Adaptec, for instance, says it's gearing up for its own expander announcement in the fourth quarter. And LSI Logic has said it's interested in releasing expanders as well.

Up to now, suppliers haven't been rushing out SAS chips, despite the modest flurry of announcements in recent months. Instead, it seems they've focused more on SATA and its near-term potential as a cost-effective replacement for SCSI.

But arguments abound over whether SATA is tough enough to withstand the kind of ongoing, transactional storage required for applications like financial services. In the view of some, SAS, with its ability to support both SATA and SAS drives interchangeably, is a clear candidate to not only replace SCSI in these kinds of apps but challenge Fibre Channel as well."I think SAS has some inevitability because it's the logical replacement for SCSI as owner of enterprise storage," says Greg Tabor, architect for SAS products at Vitesse. "SATA is good for desktops as a replacement for ATA, but it has not been able to gain the enterprise foothold, because it's not as robust."

At least one analyst takes a slightly different view. Arun Taneja of the Taneja Group consultancy, thinks SATA isn't the enterprise weakling it's made out to be. The ability of RAID to mask any drive failures, coupled with the relative cost advantage of SATA drives over SAS ones, means SATA may stay in place for awhile, even if drives must be replaced occasionally. "The cost differential doesn't matter... The price ration is favor of SATA," he says.

In general, sources view 2005 as the year when SAS takes hold. If Vitesse jolts some of its rivals into action, however, that timetable could move a bit closer.

Mary Jander, Site Editor, Byte and Switch