ESXi uses different approaches to VMFS5 and VMFS3 upgrades.
You cannot upgrade a VMFS5 datastore to VMFS6. If you have a VMFS5 datastore in your environment, create a VMFS6 datastore and migrate virtual machines from the VMFS5 datastore to VMFS6.
ESXi no longer supports VMFS3 datastores. The ESXi host automatically upgrades VMFS3 to VMFS5 when mounting existing datastores. The host performs the upgrade operation in the following circumstances:
- At the first boot after an upgrade to ESXi 7.0 or later, when the host mounts all discovered VMFS3 datastores.
- When you manually mount the VMFS3 datastores that are discovered after the boot, or mount persistently unmounted datastores.