Stakanov, et al -- ...and then Stakanov said... % % Ok, I did it and it worked. Yay :-) % So how to take a single disk and transform it with mdadm into a Raid1 without % having to restore it from backed up data (which should be there BTW, in case % things go South on you). % ... % $ sudo sgdisk /dev/sda --replicate /dev/sdb % The operation has completed successfully. % $ sudo sgdisk --randomize-guids /dev/sdb % The operation has completed successfully. ... % $ sudo mdadm --create /dev/md0 --level=1 --raid-devices=2 missing /dev/sdb2 ... % $ sudo mkfs.ext4 /dev/md0 ... % $ sudo mkdir /mnt/new-raid % $ sudo mount /dev/md0 /mnt/new-raid [snip] Glad it worked for you :-) The only thing I'd do differently is parted /dev/md0 to create a partition table and then mkfs.ext4 -L label ... /dev/md0p1 mount /d4v/md0p1 ... since I don't like allocating the whole device. But IANAL and YMMV :-) HAND :-D -- David T-G See http://justpickone.org/davidtg/email/ See http://justpickone.org/davidtg/tofu.txt