Welcome to the Community,
I'd prefer the last mentioned option:
- verify that all hardware is supported with the new version (e.g. your storage system)
- migrate the VMs from the v5.1 host to the storage/cluster. Live migration isn't possible between AMD and Intel CPUs so, that will require some downtime (and maybe reconfiguration within the guest OS!?).
- remove the v5.1 host from the vCenter Server environment
- migrate your Windows vCenter Server 5.5 to a vCenter Server Appliance 6.5U3
- create a new cluster and enable EVC on it (not a requirement, but recommended)
- live migrate the VMs
- at a later time, you may power cycle the VMs (so that they get the new CPU features), update VMware Tools, and the virtual hardware
Thanks - can someone clarify the following? It seems like moving live VMs between two vcenters is only supported on 6.0 or above. So I don't think I would be able to create a new vcenter and move the vms from the 5.5 cluster, right?
Looks like upgrading vcenter and then deploying the new individual hosts is my only option?
If you install/migrate your 5.5 vCenter to a 6.5 VCSA you can manage the old hosts as well as the new R740 (assumed you install/ordered them with 6.5)
BUUUUUUTTT.... the R805 is a AMD based Hosts and the R710 and your shiny new R740 are Intel based, so no vMotion from the AMD to Intel which means you need a downtime for migrations.
A vMotion from the R710 to new R740 is only possible with the help of EVC on the Cluster or both Cluster(old and new). For a migration maybe ok............. but i highly suggest after you remove all old hosts to lift the EVC up to Sklylake/CascadeLake and than shutdown and restart one VM (not GuestOS!) after another. Otherwise your VMs will see the CPU featureset from 10 years ago.
I'm aware of the R805. That one will be removed from the cluster prior to any of this - just 2 guests to move.
Now, I see that the R710s are not compatible with 6.5. And the R740 came with 6.7 installed, so will need to install 6.5 on it first.
My understanding is that vcenter will be upgraded first to 6.5 (into a new appliance) but will be running inside the cluster in one of the old R710, right? So basically I need to do:
a) Install 6.5 on new R740
b) Upgrade vcenter to 6.5 (will use embedded PSC)
c) Add new R740 to new cluster, storage, etc
d) Move test VMs to new cluster
e) Reboot test VMs
f) Move vcenter to new cluster
g) Vacate VMs from one R710 and remove form old cluster
h) Add new R740 to new cluster
i) Move remaining VMs and reboot when possible
Blame it all on Covid - vm admin position frozen, windows admin furloughed. Did one host upgrade many many years ago. At least I know what rm -rf and format c: can do. TIA.
Sounds ok, except for the VM reboots. In order to make the VMs aware of the new CPU features, you need to power cycle the VMs, i.e. shut down+power on. A simple reboot is not sufficient.
Regarding the EVC mode for the new cluster. It should work to select the highest possible EVC mode for the new cluster. Life migration (vMotion) from the current cluster to the new one should still work, since the powered on VMs currently have less CPU features than available.