Hi Friends,

Today morning I logged on to one of our servers (through ssh -X) to perform a routine maintenance. When I tried to open a GUI application, it failed to connect to the X server of the workstation. Eventually I ended up issuing the command

and shockingly it showed that / is 100% used. I checked / using

to check the sizes of the individual directories, which showed that only about 18% of the / is used and that confused me badly. There was no quick solutions when I googled around; but luckily I found the following link which nicely explained the issue I had:

http://www.walkernews.net/2007/07/13/df-and-du-command-show-different-used-disk-space/


All I did was found out the services responsible for those unreleased files (using lsof +L1) and restarted them. That is it. Now df reports only 18% of the disk is used and all my X things started working again, thanks to Walker.

I felt sharing it here for somebody who is having similar problem.

Cheers

Yes - as noted in the post you referenced this happens not only in Linux but also in UNIX.

The issue is that files have both "names" and "inodes". If a file is being held "open" by a process and someone deletes it they are deleting only the name. The inode is left unmolested until the process is stopped. Long ago the only way to be sure to clear the condition was by rebooting the server. A reboot worked because it killed ALL processes including whichever one was holding the file "open". LSOF is a great tool because it can help you find files held open that no longer have a name so you can resolve the issue by killing the process. (LSOF has quite a few other uses as well and is available for most flavors of UNIX as well as Linux.)