By Charles Vallhonrat

Despite many years of strong growth in storage migrating to SANs, we still live in a world where a huge amount of storage is still directly attached to servers.  Why have we not seen all storage move external for any environment with multiple servers?  Surely the SAN offers lower cost, higher data protection, and better utilization.

The fact of the matter is a lot of data remains inside servers or directly attached via a JBOD because that is the best place for it.  Maybe there is a specific performance need, or certain local control of data and access that leads to customers keep storage directly attached. Customers are savvy and until the SAN offers a better solution for their specific need, they are keeping certain storage infrastructure close to the server.

Enter shared SAS.  It looks and smells like shared storage yet offers the simplicity of Direct Attached Storage (DAS) and has no requirement for a switch or to manage a network in smaller configurations.  HP introduced a shared SAS solution - The MSA2000sa - in August 2008 and quickly SAS became 25% of the interconnect mix for MSA.  Now with the release of a generation 2 model (or G2) there are a number of improvements that will likely boost usage still further.  The G2 products is faster than the previous generation, supports more drives, supports more snapshots, supports more LUNs, supports more servers...and on and on.  But, one of the most important new features is support for 2.5" inch (aka Small Form Factor) drives.  Yep, the same type of drives used in many ProLiant servers.  In fact, with the MSA2000sa G2, the small form factor drives are same drives that are used in our HP ProLiant servers.  Talk about keeping the simplicity of DAS...

By the way, once customers get the benefit of shared storage using SAS, the MSA architecture allows them to upgrade controllers to iSCSI or Fibre Channel if they wish.  Maybe we have finally found the catalyst to remove storage from servers.

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