Yeah you are right just had the wrong situation in mind with the sparse files

At 12:04 AM 11/13/2001 +0700, Robert Elz wrote:
>     Date:        Mon, 12 Nov 2001 11:00:42 +0100
>     From:        Lars Heidieker <lars@heidieker.de>
>     Message-ID:  <5.1.0.14.0.20011112105946.02be8840@pop.puretec.de>
>
>   | Wouln't that be the other way around df showing less in use then du.
>
>No.   That should be impossible (race conditions excepted).
>
>   | I think a bunch of sparse files will cause this.
>
>No.
>
>An open file (or files) that have been unlinked is the likely cause.
>
>It also used to be the case (perhaps still is?) that if the filesys was
>mounted with softdeps, and files had been deleted, it would take a while
>for df to catch up (the space isn't actually released to the filesystem
>immediately).   On the other hand, du only ever shows the files that are
>currently in directories.
>
>A third (but very unlikely in this case I suspect) cause can be if some
>other filesystem is mounted on top of the one under consideration, and it
>is almost empty (so du finds little) but there's actually lots of files
>that are now hidden under the mount point (the space is still in use on
>the filesystem, but nothing can get at it - du included).
>
>kre