Apologies for the thread necro, but we are about to do a similar project, but rather migrate from an older ESXi 4.1 cluster to a new ESXi 5.5 cluster.
Would it cause problems to (temporarily) have 2 vcenters (one for old cluster and one for the new cluster) while we migrate VMs from the old cluster to the new cluster?
My original suggestion to the project lead was to just remove the old hosts one by one from the old vcenter and add them to the new vcenter, then rebuild the old ESXi servers once all VMs are moved to the new hosts, but the older ESXi servers had some issues in the past and the project lead doesn't want to "contaminate" the new environment with the old server problems. (although they seem fine as far as I can tell)
Also, we will be creating new LUNs and wiping out the old LUNs once everything is moved.
So his idea is to either:
1) have new LUNs on the new hosts which are in the new vcenter, then file copy (SCP) the VM folders from the old datastores to the new datastores (while the VMs are powered off, of course), then add them to the inventory on the new hosts. This option has the most downtime.
2) add the old datastores to the new ESXi servers, which are in the new vCenter and just power off vm, remove from inventory on old host, add to inventory on new host. Once all VMs are moved, we remove old datastores. This option has less downtime, but the project lead says he found some concerns from other people out there that having the same LUNs used in 2 different environments is a bad idea. But I'm not sure this qualifies as 2 different environments.
Thanks