http://blogs.vmware.com/vsphere/2011/08/new-enhanced-vsphere-50-storage-features-part-4-vsphere-storage-appliance.html
Let's start with a brief introduction. In vSphere 5.0, VMware releases a new storage appliance called the VSA. VSA is an acronym for “vSphere Storage Appliance”. This appliance is aimed at our SMB (Small and Mid-size Business) customers who may not be in a position to purchase a physical SAN or NAS array for their virtual infrastructure, and as a result, these customers do not have shared storage.
Without access to shared storage, SMB customers are unable to implement many of vSphere’s core technologies, such as vSphere HA & vMotion. Customers who decide to deploy a VSA can now benefit from many additional vSphere features without having to purchase a SAN or NAS device to provide them with shared storage.
Customers require two or three newly installed (green-field) ESXi 5.0 hosts to create a VSA cluster. The ESXi hosts must not have any virtual machines deployed & have the default logical network configuration (Management portgroup & VM portgroup). The local storage on the ESXi host should be configured into a RAID10 setup for optimal resilience. Should the server lose a disk spindle, it will not impact the VSA cluster storage. The recommendation is to use 8 local disks per ESXi; this will give optimal performance.
During the ESXi 5.0 deployment, a VMFS-5 is created on all the remaining available disk space on the ESXi servers.
Each ESXi 5.0 host will have an appliance/Virtual Machine deployed to it by the VSA cluster installer. The appliances are deployed with multiple disks (VMDKs) which allows them to use (almost) all of the VMFS-5. The appliances then present one replicated volume via NFS to each of the ESXi 5.0 hosts in the cluster. This replication of storage volumes makes the VSA very resilient to failures. All ESXi 5.0 hosts now have shared storage.
VSA Manager is the component used to manage the VSA cluster. VSA Manager is a vCenter Server 5.0 extension that you install on a vCenter Server machine. After you install it & the VSA Manager plugin is enabled, you can see the VSA Manager tab in the vSphere Client. VSA Manager will deploy & afterwards monitor the VSA cluster. Here is a screen-shot of the VSA Manager from a 3 node configuration:
The VSA manages the data replication/redundancy by dividing the local storage on the appliance into two distinct volumes, one volume becomes the replica/mirror source and the other becomes a replica/mirror destination (for a source replica on a different appliance). It then exposes the mirrored volume as an NFS volume over the network, which allows it to be mounted by all the ESXi hosts in the VSA cluster. vSphere HA & a vMotion network are also configured for all ESXi hosts in the cluster.
This is all done automatically by the installer. There is no customer intervention required to do this.
There is an obvious CAPEX saving achieved by SMB customers as there is no longer a need to purchase a dedicated SAN or NAS devices to achieve shared storage.
There is also an OPEX saving as the installation & management of the VSA may be done by the vSphere Administrator who may not have the necessary skills to manage a physical SAN or NAS array.
The installation & configuration is also much simpler than that of a physical storage array or other storage appliances.
A new vSphere Storage Appliance Technical Whitepaper is published here.
