Linux Software Raid Failure (failed disk removal and re-add)

1. check software raid status

# cat /proc/mdstat

Personalities : [raid1] 

md0 : active raid1 sdc1[1] sdb1[2](F)

  346242536 blocks [2/1] [_U]

 

unused devices: <none>

2. remove failed disk from raid

# mdadm --manage /dev/md0 --remove /dev/sdb1 

mdadm: hot removed /dev/sdb1

3. re-add failed disk to raid

# mdadm --manage /dev/md0 --add /dev/sdb1 

mdadm: re-added /dev/sdb1

4. check rebuilding status

# cat /proc/mdstat 

Personalities : [raid1] 

md0 : active raid1 sdb1[2] sdc1[1]

      346242536 blocks [2/1] [_U]

      [>....................]  recovery =  0.0% (13434/346242536) finish=145.6min speed=42192K/sec