On Tuesday March 16, mcuss@cdlsystems.com wrote: > Hello > > I've read through the Software RAID HowTo (a very helpful document) and > searched through the mailing list, but haven't been able to find the answer > to my question, so here goes: > > Suppose I have a RAID 1 (striping) RAID set up consisting of two drives, > creaiedby editing raidtab and issuing an mkraid, etc. Suppose I've made an > ext3 filesystem on this device and have files on it. > > Now, suppose this RAID device is full, and I wish to make it bigger. Is > there a way for me to add another pair of drives to this array? I've tried > doing a "raidhotadd" on my experimental box, that that didn't work. Later > reading revealed that raidhotadd is only for adding spares. I don't think > simply adding the new drives to the raidtab will help, as those changes will > only become effective if I mkraid the device, which will torch the data on > it. > > Is it possible to do this, or am I dreaming? You are dreaming. It is possible that something like this might be added one day, but not in the immediate future. If you used LVM over raid, you might be able to do something there. What you could do is: Assuming first two drives are A and B, and new drives are X and Y. And that A+B is a raid1 called /dev/md0 and that md1 md2 md3 are not in used. 1/ break the mirror: mdadm /dev/md0 -f /dev/B mdadm /dev/md0 -r /dev/B 2/ Create md1 and md2 and mirrors of old and new drives respectively, but don't include A yet: mdadm -C /dev/md1 -l1 -n2 missing /dev/B mdadm -C /dev/md2 -l1 -n2 /dev/X /dev/Y 3/ raid0 md1 and m2 together into a raid0 mdadm -C /dev/md3 -l0 -n2 /dev/md1 /dev/md2 4/ mkfs a filesystem on /dev/md3 and copy you filesystem across mkfs -J /dev/md3 mount /dev/md3 /mnt cp -ax /path/to/dev/md0/mountpoint /mnt umount /mnt 5/ unmount all and remount new unmount /path/to/dev/md0/mountpoint mount /dev/md3 /path/to/dev/md0/mountpoint 6/ make sure the data look ok 7/ put A into it's raid1 array mdadm /dev/md1 -A /dev/A 8/ make sure the arrays are assembled properly at boot time. NeilBrown - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
