3 host vSAN upgrade from 6.0 to 6.7

[Nick_Dearing_AM]

I have a three host vSAN cluster currently running vSphere 6.0. I'm in process of getting the hosts up to 6.7. vCenter is already upgraded to 6.7 U3. I want to do a fresh ESXi install for each host on USB flash drives, rather than an upgrade.

Would I be safe to put one host into maintenance mode, complete fresh install to ESXi 6.7, re-add to cluster, migrate VM's and move to the next host? Waiting to upgrade any disk formats until all hosts are complete? I know this isn't "best practice" as the hosts should match, but is it OK for short-term upgrade purposes? I'm trying to avoid total down-time as much as possible.

Thanks!

[TheBobkin]

@Nick_Dearing_AM, Yes this should be okay as it *should* just re-add the later version node to the cluster with Multicast mode as long as the disks on-disk format remains unchanged.

https://kb.vmware.com/s/article/2145248

Do take backups before proceeding and have plan in place to re-install that node on 6.0 if something doesn't go as expected and validate all is okay before doing 2nd node.

[TheBobkin]

@Nick_Dearing_AM , Just a short addendum to this:

Ensure you update the vCenter to 6.7 U3 before doing any updates to the ESXi hosts.

When adding the re-installed host to the cluster, remove the old reference to it from vCenter inventory, add the new one to the vCenter at the Datacenter level (e.g. not in the cluster), configure the vSAN networking on it and only then move it into the vSphere cluster.