Recently I had to rebuild a CentOS5 VM host as CentOS6. My VMs were stored on a RAID1 pair (seperate from the OS disks). To avoid any possibility of impacting the VM data during the re-installation, I removed the VM data disks from the host during the reinstall.
This is a companion discussion topic for the original entry at https://www.funkypenguin.co.nz/note/importing-existing-raid-devices-new-linux-installation/