VAAI

Introduction Nimble Storage arrays are one of my favourite SAN arrays to work with at the moment. However, until Nimble OS3 which was made GA on the 31st of August, 2016, there was no support for the XCOPY VAAI primitive. This meant that when performing actions such as a storage vMotion that moved data between datastores on the same array, or cloning virtual machines, the ESXi host performing the action was required to read the data from the array up through the ESXi host, and then write it back to the array, creating additional load on the ESXi host and traffic on the storage adapters and network.

OverView Back in vSphere 5 a new VAAI primitive called unmap was released. When using thin provisioned volumes or LUNs for VMFS datastores, actions such as storage vMotion, consolidating snapshots and deleting data (such as VMDK files) do not automatically reclaim the space on the underlying datastore. For example, if you have a thin provisioned 1TB datastore that has 2 x virtual machines using 400GB each, and you delete one of these virtual machines (using the ‘delete from disk’ action), the used space on the datastore will still report as 800GB.