What we have learned so far

From the troubleshooting steps that we have taken so far, we have collected quite a few key pieces of data. Let's walk through what we have learned and what we can infer from these findings:

• On our system, we have two RAID devices.

  Using the mdadm command and the contents of /proc/mdstat, we were able to determine that this system has two RAID devices—/dev/md126 and /dev/md127.

• Both RAID devices are a RAID 1 and missing a mirrored device.

  With the mdadm command and output of dmesg, we were able to identify that both RAID devices are set up as a RAID 1 device. On top of that, we were also able to see that both RAID devices were missing a disk; both the missing devices were partitions from the /dev/sdb hard disk.

• Both /dev/sdb1 and /dev/sdb2 have mismatched event counts.

  With the mdadm command, we were able to inspect the superblock details of the /dev/sdb1 and /dev/sdb2 devices. During this, we were able to see that the event counts for those devices are not matching...