vSphere: Migrate from a Thick to a Thin VMDK

Inflating a Thin VMDK to a thick VMDK is easy, just browse your Datastore, select the VDMK file you want to inflate, right mouse click on it and select inflate.
Note: Your Virtual Machines needs to be powered off and inflating a disk can take-up some time. In my test I inflated a 5 GB Thin disk on witch 3,6 GB was occupied took 8 minutes.This was on a NetApp with Fiber Channel (1GB).

But what if we want to do the opposite? There are a few way to create a Thin VMDK file:

  • Create a Virtual Machine
  • Clone to a template
  • Clone a Virtual Machine
  • Use VMware Storage VMotion to migrate the virtual machine storage

So, the most easy way to migrate a Thick VMDK file to a Thin VMDK file is to use Storage VMotion.

  1. Right click the Virtual Machine and select Migrate
  2. Select change datastore
  3. Select the Lun you want to move the Virtual Machine to
  4. Select the format. This will be Thin provisioned format of course
  5. Select finish

That’s all

About Michael
Michael Wilmsen is a VMware training/consultant (no specific order) with more than 15 years in the IT industry. Main focus is VMware vSphere, Horizon View and Site Recovery Manager with a deepdive to performance. Michael is VCDX 210, VCAP 4/5 certified, has been rewarded with the vExpert title from 2011, is a PernixPro, Nutanix Tech Champion and a Nutanix Platform Professional.

4 Comments to “vSphere: Migrate from a Thick to a Thin VMDK”

  1. By TBoy, October 13, 2010 @ 19:12

    I agree this is an easy way to migrate from Thick to Thin provisioning. However, how do you addresss the same issue on virtual machines with snapshots?

    • By Mike, October 14, 2010 @ 09:32

      You cannot, but it isn’t the best idee to leave snapshots on because the delta disk will continue to grow until the datastore will fill up

  2. By TBoy, October 13, 2010 @ 19:12

    I agree this is an easy way to migrate from Thick to Thin provisioning. However, how do you addresss the same issue on virtual machines with snapshots?

    • By Mike, October 14, 2010 @ 09:32

      You cannot, but it isn’t the best idee to leave snapshots on because the delta disk will continue to grow until the datastore will fill up

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