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

[Matt Iavarone]

On Mon, Feb 1, 2010 at 8:29 AM, Robert Grasso
<robert.grasso+nv at cedrat.com> wrote:
> Hello,
>
> I have a small server running a tool (RT : perl + mysql + apache) for our support team. I stripped down everything else. The OS is
> 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.
>
> I verified with
>
> tune2fs -l /dev/sda1
> (...)
> Block count:              8703205
> Reserved block count:     435160
>
> that is, the ordinary 5%
>
> the journal size :
>
> debugfs -R "stat <8>" /dev/sda1
>
> yields
>
> Size: 33554432 with a block size of 4096, this gives 128 MB
>
> I rebooted on the CentOS v4.8 CD #1, started "linux rescue" :
>
> mounting /dev/sda1, I get the same 29 GB used
>
> e2fsck reports a clean filesystem
>
> e2fsck -f does not reports further errors.
>
> Does anybody have a suggestion ?
>
> Best regards
> ---
> Robert GRASSO - System engineer
>
>
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> http://lists.centos.org/mailman/listinfo/centos
>

This is typical.  There were probably files deleted from the file
system that are still in use by a process.  Restarting the process
will release the files and df and du will jive.