I’ve had too many hard disk failures over the years and decided to use RAID to ensure that all my photos, email and work are always copied to two disks so that if any one of them fails I don’t lose anything.
Recently I was upgrading my system and accidentally unplugged one of these disks - I didn’t even notice until I got an automatic email warning me that one of the disks wasn’t working!
Plugging it back in and getting it working was pretty easy!
note to future self - the commands were
show what is happening
mdadm –query –detail /dev/md1
add drives back into array
mdadm –manage –add /dev/md0 /dev/hdc1
mdadm –manage –add /dev/md1 /dev/hdc2