Monday: Another one of those instances where I woke up to an alert mail:

Storage Pool 2 on XXXXXX has degraded (total number of drives: 2; number of active drives: 1).

Presumably after a system update and subsequent reboot one of the two M.2 drives couldn’t be found anymore. Not only as part of the Storage Pool but it didn’t show up at all.

First, I tried rebooting, which didn’t change anything.

And for good measure I ran the script that adds the non-Synology blessed drives again. It dutifully reported the drive models were added to the database.

And after a reboot to load the new database it still didn’t show up.

To not break anything further by hastily trying things out, I muted the alarm. The storage pool was online and working albeit being degraded. Fixing this must be postponed until time allows.

Scheduled maintenance

On Saturday my new UPS arrived and to hook it up I had to shutdown the machine. While it was powered off I removed both drives and reseated them.

When I booted up the device again the second drive mysteriously appeared. The drive was detected but the storage pool could not be repaired because the drive supposedly wasn’t compatible but adding it to the pool as replacement for the missing drive did work.

Of Note

• Both M.2 drives are identical and have the same model number. Only the one in Slot 1 was detected (Before and after patching the database)
• Loosing the electrical contact due to a software update is very unlikely.

Further proceedings

As with last time: Nothing.

Now all drives are recognised and all storage pools are working properly. Time will tell if the next update breaks the pools again. But now that I have documented the steps taken, recovery time should be negligible.