Broken filesystem

Question

Something is wrong with the filesystem on my ubuntu installation and I'm trying to fix it. I tried to use fsck but the problem is that I don't have access to sudo, when I try to run sudo I get

-bash: /usr/bin/sudo: Input/output error

A lot of other program does work as well like df, same error.

What might be worth knowing is that I'm running the installation on raid 5 (setup from ubuntu, not hardware). It might be possible that one of the disk are broken. Again I need sudo to check the status of that. So how do I fix the filesystem without sudo (or get it back)?

Also of note, I updated over 100 packages yesterday but it seems unlikely that it caused this error, including it just in case.

Answer 1

"Input/output error" is bash telling you that it has been refused access to that utility by the kernel. The kernel has unfortunately been told by the hardware that it is unavailable (or it believes it is unavailable). Typically in a single disk environment, this error would signify that a disk has failed (or is failing), as it is refusing access to those sectors of the disk that hold that utility or application (in your case, sudo).

I would boot from an Ubuntu live CD (or USB) and see if you can diagnose the issue using the utilities in the live environment. If you can see your array and your disks, it may be that the kernel has had a moment and forgotten how to interact with them. If you can't see your disks, or a disk is missing, you may be looking at array issues, which is a whole different post I'm afraid.

In RAID5, if you lose two disks in the array you lose everything. It sounds like two disks may have died and the array has basically stalled, disallowing access to anything on it (sudo being the prime example).