In order for you to make use of latest features provided by VSAN, the On-Disk Format has to be kept updated. The procedure is pretty simple but time consuming if you have large amounts of data.
Once the version is upgraded, you cannot add the older version Hosts to the VSAN cluster.
Click on the Upgrade button right next to the On-Disk Format version. On the next screen, you see a pop up with important instructions. Read them carefully and click on Yes to proceed with the Upgrade.
- Snapshot consolidation fails during the On-Disk Format version upgrades, it is always recommended to perform consolidations before or after the upgrades.
- Some of the old manully unmounted disks show up on the VSAN UI, also the status may be displayed as mixed, this does not affect the upgrade process.
Once done, you should now have the latest version installed.
Just in case your upgrade seems stuck at some point, below is a quick way to understand whats exactly happening in the background and this comes in hady for troubleshooting.
©VMware Documentation Center
Hope this was informative. Thanks!