As I mentioned in my wrap-up of VMworld 2011, one of the shiny new VMware products to hit the shelves this year is the vSphere Storage Appliance, or VSA. The VSA delivers SAN-like features to small businesses that may not have the budget, staffing, or technical sophistication to purchase a real SAN.
But the initial release of the VSA is marred by a number of serious deployment and scalability limitations. The real story behind VMware's introduction of the VSA has less to do with the VSA itself and more with VMware's relationship with its partners and its parent company, EMC.
What is the VSA?
The vSphere Storage Appliance is a cluster of virtual machine appliances that offer local storage as a unified, highly redundant datastore. A VSA cluster can currently span either two or three vSphere hosts, and it uses network-based synchronous mirroring (RAID1) combined with local RAID10 on the hosts to ensure data availability and to deliver reasonable performance. The vSphere cluster hosts are then able to connect to the VSA cluster's datastores via NFS -- effectively allowing the hosts to see and share each other's storage in real time.