If the virtual infrastructure in use is configured with vSAN, after completing the upgrade of both vCSA and ESXi hosts to version 6.7, also vSAN should be upgraded to latest version.
After the upgrade of vSphere components (vCSA and ESXi hosts), the vSAN cluster's Summary tab displays a warning message related to Disk format version.
This warning is due to vSphere 6.7 that comes with the new vSAN version 6.7.
vSAN cluster checks before the upgrade
Before upgrading the vSAN cluster, some checks must be performed to avoid possible issues or data loss during the upgrade process.
Select the vSAN cluster and go to Configure tab. Click on Disk Management under vSAN area and verify that vSAN Health Status is reported as Healthy for all disks and disk groups configured.
Make sure that no rebuilding tasks are currently running in the vSAN cluster. From vSphere Client select the vSAN cluster and go to Monitor tab. Select Resyncing Objects option under vSAN section. In this area you can check running tasks or perform a synchronization before proceeding with the upgrade by clicking Resync Throttling.
From vSphere Client select the vSAN cluster and go to Configure tab. Click Pre-Check Upgrade button before launching the upgrade to ensure vSAN can be safely upgraded.
If the Pre-Check Upgrade process reports a green flag with Ready to upgrade - pre-check completed successfully, the system is ready to be upgraded.
When the pre-checks have been completed, from Configuration tab select Disk management option under vSAN section. Click Upgrade button to perform the upgrade of your vSAN cluster.
Based on your requirements select the Allow Reduced Redundancy option.
Click Upgrade to proceed with the upgrade.
The upgrade takes place and requires some minutes to complete depending on the disks size.
When the upgrade process has been completed successfully, the system reports a green flag with the status All <disks_number> disks on version 6.0.
The procedure to upgrade vSAN is now complete. The virtual infrastructure is now running vSphere 6.7 and you are able to take benefit of new features provided.