After a update one of the 3 disks in the boot mirror refused to automount, so I have had to delete and then re-introduce the 3rd volume to the boot-mirror (is it still a mirror when you have 3 disks?).
For those of us who may want to convert to Vmware from the old Virtual PC or from Parallels the Vmware guys have added a tool to do this in a couple of 'easy" steps