ESXI converts Thick Provisioning Disk back to Thin Provision and reclaims space

Once, because of my mistake, I inflated a 2TB Thin Provisioning disk. So the space it takes up has skyrocketed from 10GB to 2TB.

In order to roll back this thing, I had to do these things:

First delete all snapshots. And consolidate if possible.

Then enable SSH on your host:

Then go to /vmfs/volumes/store-name/vm folder.

Run ls -ashl you may see that original-flat.vmdk is very big. (4TB) (The name original here is your actual virtual machine name.)

Shutdown your VM. And run the following commands:

# Copy the disk to temp.vmdk
vmkfstools -i original.vmdk -d thin temp.vmdk

# Move away the old flat.
mv original-flat.vmdk big.bin

# Use the new flat to fake the old flat.
mv temp-flat.vmdk original-flat.vmdk

# Remove disk representer.
rm temp.vmdk

Try to run ls -ashl. Hopefully you can see the new -flat.vmdk is small. Then try to start your vm again.

If everything works fine, you can delete the file: big.bin.

Finally, check the VM consumed size in VCenter:

If it is not showing up, try to create a snapshot.