3 Replies Latest reply on Oct 15, 2018 12:57 AM by SupreetK

    Will VMFS unmap freed data and give back to its backed storage after deleting a large VMDK file?

    sinoleao2018 Lurker

      I ask the question as I did the test below, and found no data block was not freed in lun level after deleting the VM.

      if ESX host frees data block in block/LUN level when deleting VMDK file, it can help the storage utilization more efficient.
      Did i miss some configuration in vsphere?

       

      1. create a thin-provisioning LUN in my storage array. The allocated size of the new LUN is zero now.

      2. mount the LUN in ESXi host as a VMFS data store.

      3. create a VM with 40GB eagerly zeroed thick VMDK in the data store.

      4. in vsphere UI, the used size of the data store is a little more than 40GB.

      5. in the storage array management UI, the allocated size of the LUN is around 40GB.

      6. delete the VM.

      7. in vsphere UI, the used size of the data store is decreased to less than 1GB.

      8. however, in the storage array management UI, the allocated size of the LUN is still around 40GB.

      9. I looked into the metadata of the LUN, no data block was not freed in lun level after deleting the VM.