Re: du -h and df -h disagree on /

[Oliver Fuchs <oliverfuchs_(_at_)_onlinehome_(_dot_)_de>]

On Wed, 08 Dec 2004, Oliver Fuchs wrote:

> On Wed, 08 Dec 2004, Otto Moerbeek wrote:
> 
> > 
> > 
> > On Wed, 8 Dec 2004, Oliver Fuchs wrote:
> > 
> > > Hi,
> > > 
> > > I have a question regarding the output of df -h and du -h on my root
> > > directory /
> > > I am running OpenBSD 3.6 on a shared hardrive with WindowsXP and a second
> > > harddrive with FreeBSD.
> > > This is my /etc/fstab:
> > >  /dev/wd0a / ffs rw,softdep 1 1
> > >  /dev/wd0h /home ffs rw,nodev,nosuid,softdep 1 2
> > >  /dev/wd0d /tmp ffs rw,nodev,nosuid,softdep 1 2
> > >  /dev/wd0g /usr ffs rw,nodev,softdep 1 2
> > >  /dev/wd0e /var ffs rw,nodev,nosuid,softdep 1 2
> > > 
> > > Now running df -h shows me this:
> > >  Filesystem    Size   Used  Avail Capacity  Mounted on
> > >  /dev/wd0a     194M   142M  42.2M    77%    /
> > >  /dev/wd0h     6.3G   196M   5.8G     3%    /home
> > >  /dev/wd0d     489M   8.0K   465M     0%    /tmp
> > >  /dev/wd0g     9.8G   1.9G   7.4G    21%    /usr
> > >  /dev/wd0e     194M  12.3M   172M     7%    /var
> > > 
> > > So the root directory / on /dev/wd0a is used with 142M of 194M.
> > > But I think that this value is incorrect because du -h / shows me this:
> > > 196M	./home
> > > 10.0K	./tmp
> > > 1.9G	./usr
> > > 12.3M	./var
> > > and for /dev/wd0a:
> > > 5.8M	./root
> > > 2.0K	./altroot
> > > 4.4M	./bin
> > > 11.3M	./sbin
> > > 34.0K	./dev
> > > 5.2M	./etc
> > > 4.0K	./mnt
> > > 2.0K	./stand
> > > 2.0K	./cdrom
> > > plus the output of ls -axlh /
> > > -rw-r--r--   2 root  wheel   770B Sep 17 19:59 .cshrc
> > > -rw-r--r--   2 root  wheel   283B Sep 17 19:59 .profile
> > > -rw-r--r--   1 root  wheel   5.1M Nov 28 17:41 bsd
> > > -rw-r--r--   1 root  wheel   5.2M Nov 28 17:41 bsd.mp
> > > -rw-r--r--   1 root  wheel   4.5M Nov 28 17:41 bsd.rd
> > > 
> > > So this is round about 50M and not as shown in df 142M
> > > for /dev/wd0a.
> > > I cannot find the answer to this disagreement but I have to points to made:
> > > 1) maybe it is depending on the fstab mount option softdep?
> > 
> > No.
> > 
> > > 2) or is it because I copied some files from my FreeBSD harddrive over to
> > > OpenBSD and this leeds to the wrong amount of df -h?
> > 
> > No.
> > 
> > Two probable causes:
> > 
> > - some programs have created files that are still open, but removed from 
> > the directory. Open files cannot be removed from the filesystem until 
> > they are closed, but du(1) will not show them. Use fstat(1) to find which 
> > files are open by programs.
> > 
> > - there are files allocated in directories that are mounted over, like 
> > /tmp, /home, /usr and /var. To find these files, boot into single user 
> > mode 9with just / mounted) and check the contents of these dirs.
> > 
> > 	-Otto
> 
> Hi Otto,
> here is what happened. While trying to find the error I did a mistake and
> umounted /var directory with the -f option. So I ended up in powering off my
> PC - did not know what to do else. Anyway, the system rebooted and running
> fsck on the not clean umounted /dev/wd0a.
> The result was this:
>  df -h:
>   Filesystem    Size   Used  Avail Capacity  Mounted on
>   /dev/wd0a     194M  41.6M   143M    23%    /
>   /dev/wd0h     6.3G   160M   5.8G     3%    /home
>   /dev/wd0d     489M   6.0K   465M     0%    /tmp
>   /dev/wd0g     9.8G   1.6G   7.7G    17%    /usr
>   /dev/wd0e     194M  12.8M   172M     7%    /var
> It seemed that the Used and the Avail values have changed their positions. 
> But I am still not sure what caused this behaviour.

Hi again,
I think I found what causes the error in df -h:
Running fsck on /dev/wd0a always gives me a SUPERBLOCK error message. This
happens only if I mount OpenBSD in FreeBSD. I made some checks and found out
so far that FreeBSD "mount" cannot handle the softdep-mount option on
/dev/wd0a. So I disabled it in fstab again and now the error did not show up
again.

Oliver
-- 
... don't touch the bang bang fruit