analyse disk usage ignoring mounts

Question

Ubuntu is complaining that my root file system is nearly full, but when I use baobab (aka "Disk Usage Analyser") or du -h it summarises the usage of all the other mounted file systems as well.

How can I exclude the other file systems which are mounted in assorted subdirectories?

Answer 1

baobab: If you want to use baobab, this is possible by mounting the root filesystem in another place and analysing that. This way, other filesystems will not be mounted in the new root mount and any files hidden by mounts under / will be uncovered and counted in your analysis.

Assuming your root filesystem is on sda1 (df will tell you which device it is):

> mkdir deleteme-later
> sudo mount /dev/sda1 deleteme-later
> baobab deleteme-later

and then tidy up when you're done:

> sudo umount deleteme-later
> rmdir deleteme-later

Alternatively you could unmount said file systems manually. You can also scan just your home folder, because it will most likely contain the source of the excessive disk space usage.

du has two options which are able to prevent counting other filesystems:

  -x, --one-file-system
          skip directories on different file systems
      --exclude=PATTERN
          exclude files that match PATTERN

Thus,

du -hx

would ignore all other mounted filesystems or

du -h --exclude /media

would ignore all mounted filesystems in /media.

If you're using du, sorting so that the biggest things appear at the bottom of the list can help decipher the output. eg:

du -hx | sort -h