Mount: can’t read superblock

We recently had a power outage in the building, which lasted longer than my UPS could handle. When I booted up my server, I could no longer mount my drive, getting the following error:

root@Eir:~# mount /dev/md0 /mnt/EirStorage/
mount: /dev/md0: can't read superblock

After fiddling about with mdadm as that’s what I used to create my /dev/md0 raid, I realized that everything was correct with the raid, still, but the issue was with the drive not being properly unmounted… Yes, exactly… Like when you pull out a USB before asking Windows nicely.

I proceeded to run the command fsck -p /dev/md0 (-p stands for “automatic repairs, no questions asked”). After which it ran the lines below:

root@Eir:~# fsck -p /dev/md0
fsck from util-linux 2.29.2
/dev/md0: recovering journal
Journal checksum error found in /dev/md0
/dev/md0 was not cleanly unmounted, check forced.
/dev/md0: Inode 3145732 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 3145734 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 3145736 extent tree (at level 1) could be narrower.  IGNORED.
/dev/md0: Inode 6619138 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 6619147 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 6619149 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 6619152 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 6619154 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 6619156 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 6619158 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 6619160 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 6619197 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 12582924 extent tree (at level 1) could be narrower.  IGNORED.
/dev/md0: Inode 12582927 extent tree (at level 1) could be narrower.  IGNORED.
/dev/md0: Inode 12582940 extent tree (at level 1) could be narrower.  IGNORED.
/dev/md0: Inode 12582947 extent tree (at level 1) could be narrower.  IGNORED.
/dev/md0: Inode 12582958 extent tree (at level 1) could be narrower.  IGNORED.
/dev/md0: Inode 12582961 extent tree (at level 1) could be narrower.  IGNORED.
/dev/md0: Inode 32178178 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 32243715 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 32243717 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 32243719 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 32243721 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: Inode 32243723 extent tree (at level 2) could be narrower.  IGNORED.
/dev/md0: /lost+found not found.  CREATED.
/dev/md0: 5460/301441024 files (0.8% non-contiguous), 418130124/2411526528 blocks

Indeed it told me that the drive was not cleanly unmounted, and on top, solved a little extra issue.

I could then run mount /dev/md0 /mnt/EirStorage without issues.

I hope this helps you too!

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