After you have finished upgrading the vSAN hosts, you can perform the disk format upgrade.

Note: If you enable encryption or deduplication and compression on an existing vSAN cluster, the on-disk format is automatically upgraded to the latest version. This procedure is not required. You can avoid reformatting the disk groups twice. See Edit vSAN Settings.


  • Verify that you are using the updated version of vCenter Server.
  • Verify that you are using the latest version of ESXi hosts.
  • Verify that the disks are in a healthy state. Navigate to the Disk Management page in the vSphere Web Client to verify the object status.
  • Verify that the hardware and software that you plan on using are certified and listed in the VMware Compatibility Guide website at
  • Verify that you have enough free space to perform the disk format upgrade. Run the RVC command, vsan.whatif_host_failures, to determine whether you have enough capacity to complete the upgrade or perform a component rebuild, in case you encounter any failure during the upgrade.
  • Verify that your hosts are not in maintenance mode. When upgrading the disk format, do not place the hosts in maintenance mode. When any member host of a vSAN cluster enters maintenance mode, the member host no longer contributes capacity to the cluster. The cluster capacity is reduced and the cluster upgrade might fail.
  • Verify that there are no component rebuilding tasks currently in progress in the vSAN cluster. See "Monitor the Resynchronization Tasks in the vSAN Cluster in vSAN Monitoring and Troubleshooting.


  1. Navigate to the vSAN cluster in the vSphere Web Client.
  2. Click the Configure tab.
  3. Under vSAN, select General.
  4. (Optional) Under On-disk Format Version, click Pre-check Upgrade.
    The upgrade pre-check analyzes the cluster to uncover any issues that might prevent a successful upgrade. Some of the items checked are host status, disk status, network status, and object status. Upgrade issues are displayed in the Disk pre-check status text box.
  5. Under On-disk Format Version, click Upgrade.
  6. Click Yes on the Upgrade dialog box to perform the upgrade of the on-disk format.


vSAN recreates each disk group in the cluster. The On-disk Format Version column displays the disk format version of storage devices in the cluster. The Disks with outdated version column indicates the number of devices using the new format. When the upgrade is successful, the Disks with outdated version is 0 (zero).

If a failure occurs during the upgrade, you can check the Resyncing Components page in the vSphere Web Client. Wait for all resynchronizations to complete, and run the upgrade again. You also can check the cluster health using the health service. After you have resolved any issues raised by the health checks, you can run the upgrade again.