The problem is we use Thin Provisioned Volumes on a 3par Array, with T10 Unmap turned off (Which is now the default) freeing space up by deleting a VM or doing a storage vmotion means the space gets freed up at the VMWare/Datastore Layer and can be reused by Vpshere but it is not reclaimed at the Array Level, issuing a vmkfstools, writes a file to the datastore and then deletes it and sends T10Unmap back to the Array, the 3par then returns this space to the free pool. This works when we do it manually we just want to automate it until VMWare decide to turn on UNMAP again.
Brett