@acebmxer It's not pretty, but its failsafe. The proceedure looked like this in our case:
Disable HA in the "old pool"
Put a host in the "old pool" into maintenance mode
Reinstall that host and connect it to XOA and then patch it
Create a "new pool" from that host
Create a new LUN or NFS share in the SAN for "new pool" and attach it to "new pool"
Live migrate VM's over from "old pool" to "new pool"
Once you've freed up another host you repeate step 2 and 3 and then join that host to "new pool". It is important that you patch it before joining it to the pool, that is done by going to Settings -> Servers in XOA and connect to it manually.
And then just continue untill you're done. Live migration is pretty reliable now days, so this works pretty good and since we had 10G network its not taking as long as it used to do with 1G network.
We did this after a major incident on our primary production site where 2 out of 4 hosts in a pool "suddenly" lost their NIC's after updating them. Since then we never updated the pools again. Standalone hosts are fine tho, they never did this.
Luckily we had 2 other pools where we could migrate the VM's to, but we couldn't realy trust the updating after that.
