Re: [gentoo-user] Diagnosing file corruption

[Bryan Gardiner]

On Thu, Aug 06, 2015 at 12:00:30PM +1000, wraeth wrote:
> On 06/08/15 10:34, Bryan Gardiner wrote:
> > After I make a fresh backup of my files, how would you recommend
> > troubleshooting this?  Run memtest or a hard drive tester?  Since
> > the files seemingly corrupted themselves after install without
> > being touched, I'm highly suspicious of the hard drive, but would
> > like to rule other things out (if say for example that
> > CONFIG_X86_INTEL_PSTATE CPU clock booster is dangerous, or
> > nvidia-drivers, or ...).  Haven't checked for corruption on /home
> > yet.
>
> One key question that doesn't seem to have been asked yet: have you
> performed an fsck on the partition? You could try booting to a livecd
> environment and running
>
>   fsck -fc /dev/sdXY
>
> (adjusting for your device schema accordingly) on your apparently
> failing partition(s) to see if there is a filesystem corruption...

Thanks very much for the suggestions, everyone.  I ended up using fsck
-fc and -fcc, which resulted in no bad blocks being detected.  I also
wanted to make sure no other files in that range of disk were
corrupted, so I extracted the extents used by the bad files:

  cat bad-files | while read file; do
      echo ">>> ${file} <<<"
      debugfs -R "dump_extents ${file}" /dev/mikasa-vg/gentoo
  done >bad-extents

found the files in the regions between the bad files:

  for block in $(seq 5302485 5302486) $(seq 5302489 5302498) $(seq 5302504 5302508); do
      inode="$(debugfs -R "icheck ${block}" /dev/mikasa-vg/gentoo 2>/dev/null | perl -ne 'if (/^\d+\s+(\d+)$/) {print $1, "\n"}')"
      if [[ -n $inode ]]; then
          echo "${block} ${inode} $(debugfs -R "ncheck ${inode}" /dev/mikasa-vg/gentoo 2>/dev/null | awk 'NR==2 {print $2}')"
      else
          echo "${block}"
      fi
  done

and file'd those to make sure that they were okay.  This is only a
personal computer, so I'm going to call this a one-off issue and move
on, and leave the stronger approaches for another day.

Thanks again!
Bryan

-- 
If people do not believe that mathematics is simple, it is only
because they do not realize how complicated life is - von Neumann