LSI Gives Limitations On DAS The Boot

Industry's first 6Gb/s SAS switch permits resource sharing, extends connection distance

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A device shipping Monday could spell the end of the resource isolation and close proximity requirements of direct-attached storage (DAS) while providing an easier and cheaper alternative to SANs. Storage solution giant LSI begins shipping the SAS6160, a 6-Gbs SAS switch that permits two or more servers to share the same physical JBOD, (just a bunch of disks), RBOD (RAID bunch of disks), or other SAS resource at distances up to 75 feet.

According to Rob Callaghan, LSI's technical marketing manager, the 6-Gbs SAS6160 is an industry first. �For the first time in the SAS world, you don't have to have islands of storage, some which are underutilized,� he said. "Now you can share storage resources those across groups of servers. No one else is doing this in six gigabit."



Alacatel, Hewlett-Packard and others make SAS switches under the 3 Gbs spec, which Callaghan said lacks table routing and other capabilities of the 6-Gbs SAS spec, devices for which began hitting the channel last year. "This allows for cascading of switches and a larger number of physical drives," Callaghan said.

The 16-port SAS6160 is a half-width 1U device that can support as many as 990 drives, physical or virtual servers, switches and other connected devices at 24 Gb/s per port and 384-Gbs total throughput. Drive isolation within a JBOD is made possible thanks to new zoning rules introduced with 6-Gbs SAS spec, sometimes known as SAS 2.0.

"For example, let's say you had two servers and a couple of JBODs, one connected to each. On JBOD one, you're using 90 percent of capacity, and JBOD two is using 20 percent. I can use the zoning function to take a portion of JBOD two and make it available to server one."


Next: Zoning Creates More Connections

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