I have a large disk full of data that I'd like to upgrade to SW RAID 1 with a minimum of downtime. Taking it offline for a day or more to rsync all the files over is a non-starter. Since I've mounted SW RAID1 drives directly with "mount -t ext3 /dev/sdX" it would seem possible to flip the process around, perhaps change the partition type with fdisk or parted, and remount as SW RAID1? I'm not trying to move over the O/S, just a data paritition with LOTS of data. So far, Google pounding has resulted in howtos like this one that's otherwise quite useful, but has a big "copy all your data over" step I'd like to skip: http://sysadmin.compxtreme.ro/how-to-migrate-a-single-disk-linux-system-to-software-raid1/ But it would seem to me that a sequence roughly like this should work without having to recopy all the files. 1) umount /var/data; 2) parted /dev/sdX (change type to fd - Linux RAID auto) 3) Set some volume parameters so it's seen as a RAID1 partition "Degraded". (parted?) 4) ??? Insert mdadm magic here ??? 5) Profit! `mount /dev/md1 /var/data` Wondering if anybody has done anything like this before... -Ben