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Codecraft
Asked: 2012-04-17 03:27:33 +0800 CST

Disk space usage doesn't add up with df & du

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I'm trying to free up some disk space - if I do a df -h, I have a filesystem called /dev/mapper/vg00-var which says its 4G, 3.8G used, 205M left.

That corresponds to my /var directory.

If I descend into /var and do du -kscxh *, the total is 2.1G

2.1G + 200M free = 2.3G... So my question is, where is the remaining 1.7G ?

linux df du

1 Answers

  1. Best Answer

    You probably have some deleted big log file, database file or something similar lying around, waiting for the process holding the file releasing it.

    In Linux, a file deletion simply unlinks the file. It actually gets deleted when there's no file handles connected to that file anymore. So, if you have a 2 GB log file which you delete manually with rm, the disk space will not be freed until you restart syslog daemon (or send HUP signal to it).

    Try 

    lsof -n | grep -i deleted

    and see if you have any deleted zombie files still floating around.

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