Paul, I wonder if my boot problem could be due to the fact that the first drive still has its partitions marked as Id 83 and not as fd for Raid Autodetect? Even though only the second drive has the actual RAID partitions created and populated on it, couldn't booting off of the first drive create a problem is the root in grub is set to a raid partition and the first live drive it finds doesn't have the correct partition ids? I've seen at least one protocol for converting to RAID-1 live that had conversion of both drives partitions Ids to Raid Autodetect (despite the fact that only one has md partitions at that point). http://www.doorbot.com/guides/linux/x86/grubraid/ Also I noticed some articles suggested adding... md=0,/dev/hda1,/dev/hde1 to the grub kernel line options as well however I can't find that grub usage documented anywhere else. Jack ps In case I wasn't clear, the second drive with the md partitions already has those partitions set to fd.