With the release of vSphere 5, VMware also released their VSA, a shared storage solution for the SMB market. VMware VSA uses the local storage in each ESXi server, presents it to the VSA appliance which in turn serves it back to the ESXi servers as shared storage. Each ESXi server needs to run a VSA appliance, and each will contain a replica of the other’s storage.
Until now the VMware VSA only supported RAID 10, which resulted in very low storage utilization. Running VMware VSA with mirroring between two ESXi server, meant that you could only use 25% of your actual storage capacity.
Now with the added support for RAID 5 and 6, VMware VSA offers a greater storage utilization rate.