strange behaviour of df command

[Mike Zupan]

your disks need a good fsck.. boot into the rescue disk and fsck them.. that
should fix them up

On 10/10/06, Atul Tyagi <tyagi.atul at gmail.com> wrote:
>
> Thanks but do u have explaination for dummies. This sounded greek to me
> :-)
>
> On 10/10/06, Manuel Arostegui Ramirez <manuel at todo-linux.com> wrote:
> >
> > El Martes, 10 de Octubre de 2006 15:58, Atul Tyagi escribió:
> > > Hi All,
> > >
> > > I am facing a little problem. I guess its more of a conceptual problem
> > > rather than a OS issue.
> > >
> > > One of my software raid partiton /dev/md4 is about 30 GB. I had put a
> > file
> > > of about 18GB in that jus for few mins and then deleted that. Now even
> > > after about 6 hrs. My RHEL4 system gives me weird output. following
> are
> > the
> > > outputs that might help you understand.
> > >
> > > df -h
> > > ===
> > >
> > > [root at pingu ~]# df -h
> > > Filesystem            Size  Used Avail Use% Mounted on
> > > /dev/md0              5.0G  2.7G  2.1G  56% /
> > > /dev/md1               99M   17M   78M  18% /boot
> > > none                 1014M     0 1014M   0% /dev/shm
> > > /dev/md2              5.0G  190M  4.5G   4% /var
> > > /dev/md4               30G   22G  5.9G  79% /usr/local/test
> > >
> > > du -hs
> > > =====
> > > [root at pingu ~]# du -hs /usr/local/test
> > > 2.7G    /usr/local/test
> > >
> > > Can some one please clear my doubt and explain why there is a such a
> > hugh
> > > difference in both the commands. Disk usage shown by df -h is 22G
> where
> > as
> > > du shows 2.7G.
> > >
> > > Would appriciate any pointer to this problem.
> > >
> > > Thanks,
> > >
> > > Atul
> >
> > quote from: http://www.acersupport.com/ess/articles/articles/14.cfm
> >
> > You may often see a difference in the output of the two commands "du"
> and
> > "df". For example, a df -t is executed on a system and it comes back
> with
> > the
> > following:
> >
> >        (/dev/root ):     216000 blocks      41950 i-nodes
> >               total:     260460 blocks      43392 i-nodes
> >
> > If you subtract the total blocks free from the total available you get:
> > 44460.
> > The command du -s (from the root directory) shows: 39130. This is a
> > discrepancy of 5300 blocks. However, there is a big difference in how
> > these
> > two utilities work. The df command takes a look at the freelist and
> gives
> > a
> > picture of how many blocks are available for use. The du command takes a
> > snapshot of the blocks in use by a file or directory, BUT, neither does
> it
> > count the blocks used by the directory entries themselves, nor does it
> > count
> > the blocks used by special files (ie. device files, named pipes, etc.).
> >
> > So, if you want to get an approximation of what is in use from looking
> at
> > the
> > df -t output you need to perform one more step.
> >
> > Perform the subtraction to determine the number of i-nodes in use and
> then
> > multiply that by 4. When you add that value to the one you got
> previously
> > you
> > will get an approximation of the total blocks in use. This will still
> not
> > match exactly!
> >
> > The general point is that things aren't always as they seem at first
> > glance.
> > There are many utilities in UNIX. Determine what it is that you really
> > want
> > to know and then use the appropriate tool.
> >
> > --
> > Manuel Arostegui Ramirez.
> >
> > Electronic Mail is not secure, may not be read every day, and should not
> > be used for urgent or sensitive issues.
> >
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