I am in the process of putting together an implementation plan to upgrade a ESXi cluster of 5 servers housing 150 virtual machine to ESXi 5.5. We have no capacity to vMotion the virtual machine between hosts and so we are adding a 6th server to the cluster to aid the process which i detail below. Really I'm just wanting someone to do a quick sanity check on the proposal I have in place and point me in the right direction or any big problems with what i am proposing.
1.Upgrade the firmware on the vSphere 4.1 server.
2. Upgrade vSphere server from 4.1 to 5.5 via in place upgrade (run install over the top).
3. Add a 6th server that is the same make\ model to the cluster.
4. vMotion guests from server 1 to the 6th server.
5. Upgrade firmware on server one and then reinstall ESXi 5.5 and add back to the cluster.
6. And then basically go around all servers moving the guests and then reinstalling ESXi 5.5 and adding to the cluster.
Any flaws in this? Can ESXi 5.5 and 4.1 coexist in the same cluster whilst the upgrades are taking place?
Thanks for looking