Sooner or later you may have to do some «serious work» outside of the vCenter GUI or vCenter client. PowerCLI on a Windows machine is the obvious choice here. I’m in the middle of upgrading an ESXi 5.0 cluster with a non-SSO based vCenter to a new 5.5 cluster with a SSO-capable vCenter 5.5 server. Downtime is critical, and migration from one cluster to a new when using dvSwitches does not work without some tinkering.
Doing some reading I’ve found that one way to do this is to create old school vSwitches with all the needed VLAN’s and change the Network on all VMs from dvSwitches to vSwitches. Testing show a packet loss of 1-2 packets, which is acceptable. The main issue here is creating the new vSwitches. No biggie if you have a SOHO lab, but with 12 servers and 40 VLANs we’re talking click-click-click if you’re using a GUI.
First of all – get PowerCLI installed and configured
Check the references for PowerCLI and Virtual Switches
Then read these http://www.mikelaverick.com/2014/01/back-to-basics-configuring-standard-vswitch-with-powercli-part-three-of-three/ as well as http://www.gabesvirtualworld.com/migrating-distributed-vswitch-to-new-vcenter/ and you should be ready to go!
Another issue here is naturally if you use EVC in you cluster, and maybe stepped up a notch if the new cluster have more recent hardware. We’re in this situation, going from Dell 11G to 12G/13G servers, and we do have to reboot the machines anyhow. To get it somewhat smooth I intend to fill one of the ESXi 5.0 servers with as many VMs as common sense tells me to, remove it from the old vCenter and add it to the new SSO-enabled vCenter. The VMs on this particular server will be shut down and then migrated onto the new cluster, and probably upgraded with the newer hardware version/VMwareTools.