On Mon, Apr 15, 2019 at 02:04:09PM +0500, Roman Mamedov wrote: > I have a 2-device RAID0 with mdadm. I would like to replace one disk with > a new one, while keeping the array online. Well, it's possible ... just not intuitive. Maybe a bit risky as well? | set up some test devices with random data # truncate -s 100M a b c # shred -v -n 1 a b c # losetup --find --show a /dev/loop0 # losetup --find --show b /dev/loop1 # losetup --find --show c /dev/loop2 | create a 2-device RAID 0 and checksum # mdadm --create /dev/md42 --level=0 --raid-devices=2 /dev/loop[01] # md5sum /dev/md42 7d1bba7a97467fd97d60d5e0303e4785 /dev/md42 | replace /dev/loop0 with /dev/loop2 # mdadm --grow /dev/md42 --level=5 mdadm: level of /dev/md42 changed to raid5 # mdadm --manage /dev/md42 --add-spare /dev/loop2 --replace /dev/loop0 --with /dev/loop2 mdadm: added /dev/loop2 mdadm: Marked /dev/loop0 (device 0 in /dev/md42) for replacement mdadm: Marked /dev/loop2 in /dev/md42 as replacement for device 0 # mdadm --wait /dev/md42 # mdadm --grow /dev/md42 --level=0 mdadm: level of /dev/md42 changed to raid0 | see if data is still intact # md5sum /dev/md42 7d1bba7a97467fd97d60d5e0303e4785 /dev/md42 Regards Andreas Klauer
