SUMMARY: Discrepancies between "df" and "du" outputs

From: Loris Serena <>
Date: Wed Nov 30 2005 - 09:42:30 EST
Thank you to all who replied (too many to mention)

>From the FAQ:

Subject: 5.10)   Where is my disk space? The "du" and "df" commands

   If a process is holding open a file, and that file is removed, the space
   belonging to the file is not freed until the process either exits or
   closes the file.  This space is counted by "df" but not by "du".  This
   often happens in /var/log or /var/adm when a long-running process (e.g.
   syslog) is holding open a file.  In the case of syslog, send it a HUP
   (e.g.  kill -HUP <syslog's process ID>).

   You can use LSOF
<> )
   to find which processes are holding open a particular file.

   Thanks to Stefan Voss <s dot voss at> and
        Michael R. Zika <zika at oconto dot tamu dot edu>

   Under Solaris 2.6 and later, files which have been unlinked can
   still be accessed through the /proc interface.  If a process is
   holding open such a file for writing, but it's inconvenient or
   impractical to kill the process or get it to close the file, you can
   free up the disk space by truncating (not removing) the file from
   under /proc; e.g.,

        # cd /proc/1234/fd
        # ls -l
        c---------   1 root      24,  12 Jan  1 11:33 0
        c---------   1 root      24,  12 Jan  1 11:33 1
        c---------   1 root      24,  12 Jan  1 11:33 2
        --w-------   1 root    314159265 Jan  1 11:37 3
        # : > 3
        # ls -l
        c---------   1 root      24,  12 Jan  1 11:33 0
        c---------   1 root      24,  12 Jan  1 11:33 1
        c---------   1 root      24,  12 Jan  1 11:33 2
        --w-------   1 root            0 Jan  1 11:38 3

   Thanks to Dan Astoorian <djast at cs dot toronto dot edu>

   Brian Poole <raj at cerias dot purdue dot edu> writes:

           Another possible cause of df & du disagreeing is if the files are
           being 'hidden' under a mount.  I ran into this recently where I
           had a large number of files in /tmp (from adding patches in
           user mode) that were on the root partition.  Thus when I was
           looking for them in multiuser mode, I couldn't find them because
           of the tmpfs overlay. I exported the root partition via NFS and
           upon mounting it found the hidden files and deleted them.

>  -----Original Message-----
> From: 	Loris Serena  
> Sent:	30 November 2005 12:54
> To:
> Subject:	Discrepancies between "df" and "du" outputs
> Hello Managers, 
> On a Production V240 running Solaris 9 I came across the following:
> [itl-app2]/app1$ df 
> <snip>
> /dev/md/dsk/d116       7.0G   6.4G   555M    93%    /app1
> [itl-app2]/app1$ du -sk .
> 1432714 .
> Am I missing something here or is there a reason why df reports 6.4Gb
> while du only reports 1.4Gb?
> And more important, how do I get those missing 5Gb back in df?
> Thanks in advance for your help
> Loris
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Received on Wed Nov 30 09:43:18 2005

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