How to fix auto-read-only mdadm.

This guide shows you a simple way to fix your mdadm raid based drives which are not syncing or in the auto-read-only mode.

To find the names of your drives which are under auto-read-only mode or not syncing

cat /proc/mdstat

Force the drives to sync.

mdadm --readwrite /dev/md9

Replace md9 with the name of the drive like md127 etc.
server ~ # cat /proc/mdstat
Personalities : [raid0] [raid1] [raid6] [raid5] [raid4] [raid10] [linear] [multipath]
md125 : active (auto-read-only) raid1 sda1[0] sdb1[1]
      192640 blocks [2/2] [UU]

md126 : active raid1 sda5[0] sdb5[1]
      97650944 blocks [2/2] [UU]

md127 : active raid1 sdb2[1] sda2[0]
      97659008 blocks [2/2] [UU]
      [=>...................]  resync =  8.8% (8686848/97659008) finish=64.0min speed=23148K/sec

md128 : active (auto-read-only) raid1 sdb6[1] sda6[0]
      288875200 blocks [2/2] [UU]

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