I have read http://www.virtualizationteam.com/virtualization-vmware/vsphere-virtualization-vmware/vmware-esx-4-r... on how to zero fill a vmdk file used by Windows so that unused storage can be free up to be reused by the thin provisioning SAN storage.
However, I realize that if I delete or move VMs out of a VMFS volume that is thin provisioned from a SAN storage, the free space is not reclaimed by the SAN storage unless I zero-fill the VMFS volume as well. So how do I do this since the the vmdk files are no longer there for me to run vmkfstools -w /vmfs/volume/xxx/xxx.vmdk? Running cat /dev/zero > zero.bin;sync;sleep 1;sync;rm -f zero.bin is out too because it freeze up other VMs in the same volume.
If I have to shutdown the VMs just to free up the storage, then thin provisioning is not worth using at all consider the amount of downtime and effort to keep it's demanding storage usage in check. Especially when storage is so cheap these days.
