I recently set out to recreate my vCenter installation since I was still running on Windows Server 2003 R2 64-bit and wanted to the set it up on Windows Server 2008 R2. The problem here was that my Management Network was attached to a dvSwitch (Distributed Virtual Switch). I’ll briefly outline the process of how I removed each host (3 hosts in total) from vCenter, attaching the host to the brand new vCenter installation with only about 10 minutes total virtual machine (VM) downtime. This can actually be done with no downtime if planned properly and aware of the possible hiccups.
The new environment is now up and running, and after refining the process (poking around a lot), it only takes about 10 minutes to move each host. This was done on vSphere 5 (moving from vSphere 5 to Update 1).