title: Size of hidden folders under mount points
body: <p>I am trying to guess the disk used on a linux system. The problem is that with commands like 'du -kxa / |sort -g'  I see there is less space used than the filesystem reports (8Gb from a partition of 19Gb). I suspect that there are hidden files and folders under several mount points. I can't unmount the disks because is a production machine and it can't be stopped easily.</p>
  
  <p>The question is: </p>
  
  <p>On linux how can I get the folders and files hidden under a mount point? Is there any way to measure this space?</p>
  
  <p>Linux version: Redhat enterprise linux server 5.3.</p>