I have about 25 VMs on Hyper-v in a 4 node Windows 2008 Failover cluster. I created the first 6 or so VMs before I learned about using volume GUIDs instead of drive letters. How can I successfully change the existing VMs using drive letters to use volume GUIDs. I learned the hard way that you simply cannot go into Failover Clustering and change the drive letter of the shared storage object since when the VM restarts, it no longer finds itself and getting it back is a difficult process.
I hear there is a possibility of manually editing the XML for the VM, but I also understand this is not a supported option and I am not sure it would work anyway.