What explains the discrepancy in usage (82 GB vs 13 GB) that I see below?
Using
df:$ df -h / Filesystem Size Used Avail Use% Mounted on /dev/sda2 96G 82G 9.9G 90% /Using
du:$ sudo du -cshx / 13G / 13G total
asked Apr 11, 2017 at 13:43
Amelio Vazquez-Reina
43.1k81 gold badges211 silver badges300 bronze badges
1 Answer
-x option is a false friend as its purpose is to skip things. That option never gives you the complete picture.
To get a complete listing, use bind mounts and then du, ncdu, xdiskusage, baobab or whatever you wish on the bound directory without skip options:
mkdir /mnt/root
mount --bind / /mnt/root
ncdu /mnt/root
Then you might discover you have lots of stuff in /mnt/backup (because it wasn't mounted when the backup task ran), or a giant file in /dev (result of a dd if=/dev/zero of=/dev/sdx when no /dev/sdx existed and no tmpfs was mounted in /dev).
It could also be a deleted file still used by a process, but people don't usually ask about it as it's gone after reboot. It could also be a filesystem inconsistency, but that too would be gone after reboot (if it forces fsck in the process).
-
Thanks! Rebooting the machine did it +1. Interesting that
du"loses" track of space until I restarted the machineAmelio Vazquez-Reina– Amelio Vazquez-Reina2017-04-11 14:38:24 +00:00Commented Apr 11, 2017 at 14:38 -
2@AmelioVazquez-Reina The usual reason is that there's a large deleted file that some process still has open. The file contents don't go away until the process closes it, but
ducan't count it because it just traverses the directory.Barmar– Barmar2017-05-22 19:56:48 +00:00Commented May 22, 2017 at 19:56
ducan't see it?lsof +L1.