MORE background:
Here's the situation. It's more of a question than a problem:
I have configured a new 5.5 vSphere environment with all new hardware - 3 new ESXi Hosts, 2 new SANs, new 5.5 vCSA. I have decommissioned the vcenter 4.1 server managing vSphere 4.1 and have successfully added the 4.1 hosts to a new cluster in the 5.5 datacenter. I have 4 hosts running ESXi 4.1 in one cluster and 3 hosts running ESXi 5.5 in another cluster. All managed by the 5.5 vCSA.
We have been performing cold storage migrations of the VMs on the 4.1 cluster to the 5.5 cluster. But we have several mission critical servers that cannot be down for the time it's going to take to migrate them to the new cluster. Is it possible to detach and remove one of the 4.1 hosts, install 5.1 or 5.5 on it and join it to the 4.1 cluster so that I can vmotion those VMs from the 4.1 hosts to the 5.1 host in the 4.1 cluster, then from that host, vmotion the VMs to the new 5.5 cluster?
I have disconnected and removed the 4th host from the 4.1 cluster so that I can begin the upgrade. See the attachment...