[CentOS] Unable to find the used space

Peter Kjellström wrote:
> 
> As an addition to what others have already said. You'll also miss
> things "hidden under mounts". That is, if you had 5G in /var/log on the
> root file system and then mounted a different device on /var/log, then
> that 5G would still be there but invisible.

What I usually do in cases like this, is to bind mount root to somewhere 
else - and then run 'du' or whatever using the bind mount point - this 
will show up any 'hidden under mounts' data - something like:

  mkdir /var/run/mnt
  mount --bind / /var/run/mnt
  du -sh /var/run/mnt/*

James Pearson