When a thin-provisioned VM is deleted, the underlying array is not informed that the data is no longer in use (this is an expected behavior in vSphere – that’s how it works) and, when writes occur, the previously allocated blocks must be first purged. There is a manual procedure, described here, to manually trigger the unmap of these blocks. What is not working as expected with 3PAR arrays is that when a write in thin provision mode occurs on previously written blocks, ASIC cannot intercept zeroes and an unexpected data format leads to poor write performances. The same condition would not happen if you restore thin provisioned disks on newly created 3PAR virtual volume.