DF & DU report different size

[Michael Ault]

The important thing is what does Oracle think it is
using? Look at the dba_tablespaces or dba_datafiles
internal Oracle table and see what datafiles it has in
place. Also look at v$logfile.

I wouldn't go messing with Oracle owned files,
especially any that end in .dbf or .log. You could
bring the DBAs down on you pretty fast. Oracle
protects itself from just about everything except
operator error. Also remember that Linux will allow
you to delete in use files. 

Mike Ault


--- Rick Stevens <rstevens at vitalstream.com> wrote:
> Tech Guy wrote:
> > Hello,
> > 
> > I have a file system which is 12GB in size. I have
> oracle on this 
> > filesystem. df shows me 100% on that filesystem
> but when I use du, I 
> > find only 6GB is been used. I donot know where the
> rest 6GB is ?
> 
> df looks at the raw inode data for the partition, du
> looks at the
> filesystem.
> 
> > I assume there are open files. I tried the command
> "fuser" on that 
> > filesystem and I see 100s of processs which are
> oracle.
> > I also tried lsof and see many processes again
> that are oracle.
> > I am not sure if I can kill those processes
> > 
> > Has anyone know a better way to find which is
> using the diskspace and 
> > how to clear it without having to reboot the
> server.
> 
> I don't think you have a problem.  Oracle will take
> all of the inodes
> it can when it fires up, so df will show it as full.
>  Remember that
> df and du look at different things.  For example,
> look at this on one of
> my systems:
> 
> 	[root at prophead root]# df -h /images
> 	Filesystem            Size  Used Avail Use% Mounted
> on
> 	/dev/hda2              40G   23G   15G  60% /images
> 
> 	[root at prophead root]# du -hs /images
> 	46G     /images
> 
> So df shows me using 23GB on /images, but du shows
> 46G.  Why the
> difference?  Look at the output of mount (extra
> stuff deleted):
> 
> 	[root at prophead root]# mount
> 	/dev/hda2 on /images type ext3 (rw)
> 	/dev/hdb1 on /images/Archives type ext3 (rw)
> 
> See?  /images itself is only a 40GB partition and
> 23GB is used.
> HOWEVER, /dev/hdb1 is mounted on /images/Archives,
> and:
> 
> 	[root at prophead root]# du -hs /images/Archives
> 	24G     /images/Archives
> 
> So there's where the extra space is sucked up.  du
> is showing me that
> 23GB worth of inodes is in use, while du (when it
> examines the
> filesystem) finds the 24GB on the other partition as
> well as the space
> used on /images.
> 
> What I'm saying is that the Oracle partition has all
> of its inodes in
> use (Oracle does that), but in actuality, only 6GB
> is in active
> filesystems.  I don't think you have a problem.  You
> can check by
> preventing Oracle from starting at boot and
> rebooting the system.  THEN
> do your "df/du" stuff.  If you're satisfied then,
> start Oracle.
>
----------------------------------------------------------------------
> - Rick Stevens, Senior Systems Engineer    
> rstevens at vitalstream.com -
> - VitalStream, Inc.                      
> http://www.vitalstream.com -
> -                                                   
>                 -
> -         Microsoft Windows:  Proof that P.T. Barnum
> was right       -
>
----------------------------------------------------------------------
> 
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Michael R. Ault
Senior Consultant
Burleson Oracle Consulting
770-754-9057
www.ault.cc
www.remote-dba.com