[CentOS] du vs df size difference
Peter A
loony at loonybin.org
Wed Sep 30 21:09:47 UTC 2009
Cut'n'paste from a tutorial I'm writing right now:
Check with lsof if there are any very large files that are already deleted but
are still open by some processes.
# df -h .
Filesystem Size Used Avail Use% Mounted on
/dev/md0 194M 32M 153M 18% /boot
# dd if=/dev/zero of=testfile bs=1024000 count=50
50+0 records in
50+0 records out
51200000 bytes (51 MB) copied, 0.370919 s, 138 MB/s
# df -h .
Filesystem Size Used Avail Use% Mounted on
/dev/md0 194M 81M 104M 44% /boot
# vi testfile
<wait till vi comes up, then crtl-z and bg the process>
# rm testfile
# df -h .
Filesystem Size Used Avail Use% Mounted on
/dev/md0 194M 81M 104M 44% /boot
< quit vi>
# df -h .
Filesystem Size Used Avail Use% Mounted on
/dev/md0 194M 32M 153M 18% /boot
Also verify that your fs doesn't have a insane root reserved space set.
# df -h .
Filesystem Size Used Avail Use% Mounted on
/dev/md0 194M 32M 153M 18% /boot
# tune2fs -m 50 /dev/md0
tune2fs 1.41.4 (27-Jan-2009)
Setting reserved blocks percentage to 50% (102368 blocks)
# df -h .
Filesystem Size Used Avail Use% Mounted on
/dev/md0 194M 32M 63M 34% /boot
THere are of course other reasons but those two are a common problem.
Peter.
On Wednesday 30 September 2009 16:59:25 Ryan Pugatch wrote:
> Hi all,
>
> Curious issue.. looking in to how much disk space is being used on a
> machine (CentOS 5.3). When I compare the output of du vs df, I am
> seeing a 12GB difference with du saying 8G used and df saying 20G used.
>
> # du -hcx /
> 8.0G total
>
> # df -h /
> Filesystem Size Used Avail Use% Mounted on
> /dev/xvda3 22G 20G 637M 97% /
>
> I recognize that in most cases du and df are not going to report the
> same but I am concerned about having a 12GB disparity. Does anyone have
> any thoughts about this or reason as to why there is a big difference?
> I have read a few articles online about it and none have really shown
> such a large difference.
>
> Thanks
>
>
>
> Ryan Pugatch
> Systems Administrator, TripAdvisor
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