Inactive raid1 partition failure

[Alex]

Hi,

> It looks like a device is completely missing?
>
> blkid > blkid.txt
>
> Then for each md device UUID pair (the md UUID will show up twice in
> blkid for each of the three arrays):
>
> mdadm -E <dev1> <dev2>  >> mdXraidstats.txt
>
> Where X=the md device from mdstat. That way you get the superblock
> from each device making up each array into an array specific text
> file. They can go all in one file, but it's easier to keep things
> separate.
>
> journalctl -b -l -o short-monotonic > journal.txt
> /etc/mdadm/mdadm.conf
>
> Post those files somewhere and the URL here.
>
> The journal should say why it wasn't assembled. But the main thing is
> you should get copies of all device superblocks before you do anything
> else, especially reading around the internet where often people get
> the idea that they need to use -C to recreate an array which
> obliterates the old metadata and almost invariably kills their data.

Thanks so much for your help. In the process of disconnecting the LSI
controller and power cable connected to the disks, somehow the power
cable at the power supply side was loose for one of the other system
drives. Using these commands, I was able to figure out there really
was a device physically missing.

I panicked a bit, and didn't want to do something stupid (like mdadm
-C) before passing it by at least one other person. After connecting
the power cable, I was able to easily "mdadm --add" the drives back
and rebuild both degraded arrays. The /var/backup partition came up
automatically.

Another great mdadm command to know is --details.

Thanks again guys,
Alex