After enabling vSAN unmap on the cluster and running trim/unmap in guest no space is reclaimed on the datastore

Products

• VMware vSAN

Issue/Introduction

After enabling unmap on the vSAN datastore, and running trim or unmap in the guest after deleting data, no space is freed on the vSAN datastore.

Environment

vSAN OSA

Cause

The VM level advanced setting disk.scsiUnmapAllowed is not present or is set to False.

This setting is required to allow the guest OS to pass the unmap commands to the underlying storage layer.

Resolution

• Power off the VM
• Edit the VM settings in the vCenter UI
  • Go to Advanced Parameters tab and filter for disk.scsiUnmapAllowed
    • If present but set to False change the option to True

    • If not present add the setting and set to True
      
  • Save the addition with the OK button
    
• Power on the VM
• Run trim or unmap in guest after deleting data
• Verify the data is made available on the underlying datastore

Additional Information

Procedure to enable vSAN TRIM/Unmap