Identifying a bigger issue

Earlier while using mdadm to look at the current status of md127, we could see that the RAID device md127 had a disk removed from service. While looking through /proc/mdstat we discovered that there is another RAID device /dev/md126, and that too has a disk removed from service.

Another interesting item that we can see is that the RAID device /dev/md126 is a surviving disk: /dev/sda1. This is interesting because the surviving disk for /dev/md127 is /dev/sda2. If we remember from the earlier chapter /dev/sda1 and /dev/sda2 are simply 2 partitions from the same physical disk. Given the fact that both RAID devices have a missing drive and that our logs state that /dev/md127 had /dev/sdb1 removed and re-added. It is likely that both /dev/md127 and /dev/md126 are using partitions from /dev/sdb.

Since /proc/mdstat only has two statuses for RAID devices, up or down, we can confirm whether the second disk has actually been removed from /dev/md126 using the --detail flag...