[CentOS] very large difference between df and du (10 GB, hard to believe)

Todd Denniston Todd.Denniston at tsb.cranrdte.navy.mil
Mon Feb 1 16:00:27 UTC 2010


Robert Grasso wrote, On 02/01/2010 10:29 AM:
> Hello,
<SNIP>
> CentOS 4.8. I noticed a difference between df and du which is hard to believe :
> 
> according to df, I am using 29 GB
> [root at cedrat-rt ~]$ df -h
> Filesystem            Size  Used Avail Use% Mounted on
> /dev/sda1              33G   29G  2.8G  92% /
> none                  506M     0  506M   0% /dev/shm
> 
> (there are no other partitions - ok, I could have partitioned it a bit more)
> but according to 
> 
> du -kshxc /*
> my largest directory is /var (because of mysql) and the grand total is
> 19 GB
> 
> I have a 10 GB difference between both outputs.
<SNIP>
> e2fsck reports a clean filesystem
<SNIP>
> Does anybody have a suggestion ?

<commentary on options>
-k is 1k block size
-h is print human readable (with appropriate extensions)
which ever of them is last wins for display... I suggest only using one though, to reduce possible
confusion.
for large measurements I usually use -m,
of course it could be fun to use --block-size=1024M instead, i.e., 1G.
</commentary on options>

I too would expect them to come close to matching, unless you have a lot of 3.5k (or less) files in
a 4k inode file system.

du -shxc --count-links /*
du -shxc --apparent-size /*
du -shxc --count-links --apparent-size /*

-- 
Todd Denniston
Crane Division, Naval Surface Warfare Center (NSWC Crane)
Harnessing the Power of Technology for the Warfighter


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