vSphere Storage Appliance
vSphere Storage Appliance (VSA) is an appliance designed for small to medium businesses (SMBs) (20 to 35 VMs), allowing access to shared storage at a lower cost by using advanced features such as HA, DRS, DPM, FT, and vMotion. The appliance, available only for vSphere 5, is deployed as a VM on each ESXi server (distributed as a 3-GB OVF file). VSAs occupy the available space on the local disks of ESXi servers and show an NFS volume replicated by the ESXi server.
The replication of local storage on another ESXi server ensures redundancy if a host server is out of service. When a VSA node is out of service, the VSA Manager switches IP addresses and shared storage to the replicated VSA. This is done without service interruption for that datastore’s VMs.
VSA supports 2 or 3 ESXi servers in a cluster, and up to 25 VMs in a two-node configuration or up to 35 VMs in a three-node configuration.
Therefore, there are two deployment configurations for VSA: Two ESXi servers with one VSA and the VSA cluster service installed on vCenter, or, as illustrated in Figure 3.21, three ESXi servers with one VSA.
Figure 3.21. VSA deployment configuration.
VSA Manager (installed as a plug-in in vCenter Server) is the administrative interface of the VSA cluster. It enables monitoring of the cluster’s state and allows maintenance and VSA-node replacement operations.
The VSA appliance has the following minimum requirements:
- 6 GB RAM
- 4, 6, or 8 identical disks (same size, same characteristics), configured in RAID 5, RAID 6, or RAID 10
- 4 1-GB network cards
- 2 VLANs configured on physical switches
Because vCenter Server provides VSA management, it must be placed outside the VSA cluster—either in a VM outside the cluster or on a dedicated physical server. Note that this is the only case in which VMware recommends putting vCenter Server on a physical server.
Installing the appliance is rather simple and quick (approximately 10 minutes) and requires no particular storage skill.