Who has not had that under Linux already, that super blocks are shot dead. The Superblock contains information about the management of the file system used:
But what if you see yourself confronted with such a syslog message and nothing works?
mount: wrong fs type, bad option, bad superblock on /dev/nbd0p2, missing codepage or helper program, or other error
Most of the time you can not access the file system anymore. In my case that was a proxmox image of a VM, which then could not be started.
In my case, I first made a copy of the image on a sufficiently large other partition with dd. This takes different lengths depending on the size, but is necessary because the copy always works better and freer.
The first tool is
In this way I can show the distribution of the partitions. And with
e2fsck -f /dev/nbd0p1
I do a filecheck. With
mke2fs -n /dev/nbd0p1
I will be shown the super blocks, which I can then repair with.
e2fsck -f -y -b <Superblock> /dev/nbd0p1
Finally, the partition can be mounted on again
mount /dev/nbd0p1 /mnt
and I come back to the lost data believed. For me it was important configuration files, which I had urgently needed when reinstalling the VM, after all, it was a week's work.