Converting your VMs and Template Disks to Thin

The tool we mainly make use of is vmkfstools to convert the thick disks to thin.

We'll be using the ESX console to perform this operation.

First, power off the VM.

Use vCenter to find the host the VM is on and the associated datastore location.

Log into the ESX host's remote console as root user.

Convert the original thick .vmdk into a thin one

vmkfstools -i THEVMNAME.vmdk -d thin thinTHEVMNAME.vmdk

Move the original .vmdk flat file out of the way.

vmkfstools -E THEVMNAME.vmdk orig-THEVMNAME.vmdk

Move new thin .vmdk flat file into place

vmkfstools -E thinTHEVMNAME.vmdk THEVMNAME.vmdk

In vCenter remove the VM from inventory and add it back again, otherwise the disk may not show as 'Thin'.

Ensure that the VM boots up and all drives are available.

If things test out ok you can remove the original disk file, using vmkfstools is the proper way so the datastore knows it's gone.

vmkfstools -U orig-THEVMNAME.vmdk