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add a new disk to raid1 array

I'm in the processes of converting a 2 scsi disk (both 18gb identical drives) running LVM to LVM on software raid1. I created a raid array on the spare, added /dev/md1 to the LVM vg, migrated the extends and removed the other drive.

I tried to add the original drive into the raid set and realized I accidentally set the array size to 1 disk. When I add the new disk, it is added as a spare, not a mirror.

Is there a way to change the size of a raid1 array (using mdadm or raidtools) so I can add the mirror disk properly? I'd like to avoid going through the LVM migration step two more times.

I'd like to do this live (this the system disk so unmounting is not possible) but I can boot a rescue CD and migrate that way if necessary.

Code:

man mdadm:



-n --raid-devices=



specify the numer..... blablabla



This number can only be changed using --grow for RAID1 arrays, and only on kernels which provide necessary support.

so it seems you could add disks, but I've never done that. get a backup before you try.