By Kevin Komiega
March 31, 2006—SAN configurations that use Serial Attached SCSI (SAS) as a fabric interconnect are moving from the drawing board to the data center. For example, LSI Logic plans to unveil the first fabric switch based on SAS at next week's Storage Networking World conference and has hopes that small to medium-sized businesses (SMBs) will eventually opt for SAS-based SANs over competing technologies such as Fibre Channel and iSCSI.
LSI's 1U SAS switch has 36 ports and is built on the same crossbar switching technology used in some of the company's processors. Using copper cables, the switch supports connection distances up to 8 meters and is designed for workgroup or rack-mounted server-storage environments requiring support for as many as 10 servers connected to one or more SAS storage arrays.
SAS was originally designed as a next-generation replacement for parallel SCSI, but the industry has come to realize that SAS can scale, allows multiple hosts to connect to multiple storage arrays, and offers redundant paths—much like a traditional SAN fabric.
According to Charlie Kraus, director of LSI Logic's HBA business unit, SAS-based SANs have a role in a storage world dominated by Fibre Channel. "There are a lot of companies that don't have a SAN yet because they are too expensive and complex. There is still very little adoption of Fibre Channel SANs in the SMB market. It has been a dud," says Kraus.
LSI's aim is to make SAS fabrics simpler to manage than their Fibre Channel counterparts at a considerably lower price than traditional Fibre Channel SANs. But there are tradeoffs to consider. For example, SAS-based SANs are limited in two ways: distance and scalability.
SAS fabrics have a distance limitation of 8 meters, and LSI claims it is only possible to build a switch with up to 100 ports. But Kraus says that's enough for many end users. "It's a much more flexible storage network for small enterprises with a relatively low number of servers and storage devices," he says.
LSI plans to ship prototypes of the SAS switch in June and expects the devices to be generally available toward year-end. Pricing has yet to be determined.