Author: Falko Timme <ft [at] falkotimme [dot] com>
This guide shows how to remove a failed hard drive from a Linux RAID1 array (software RAID), and how to add a new hard disk to the RAID1 array without losing data.
I do not issue any guarantee that this will work for you!
1 Preliminary Note
In this example I have two hard drives, /dev/sda and /dev/sdb, with the partitions /dev/sda1 and /dev/sda2 as well as /dev/sdb1 and /dev/sdb2.
/dev/sda1 and /dev/sdb1 make up the RAID1 array /dev/md0.
/dev/sda2 and /dev/sdb2 make up the RAID1 array /dev/md1.
/dev/sda1 + /dev/sdb1 = /dev/md0
/dev/sda2 + /dev/sdb2 = /dev/md1
/dev/sdb has failed, and we want to replace it.