Differences in reporting by du df and usedbydataset

[Jason Breitman]

There are many open files as the server is a file server and I can see 60 files open that have been deleted.
9 of those files belong to the user that I detailed below.

Weekly zpool scrubs are run.

I appreciate your response, but am not convinced that those 9 files add up to the 18 GB difference for the user below.
I can see the size of the files from lsof which adds up to just over 1 MB.


Jason Breitman
jbreitman at zxcvm.com



On Apr 15, 2014, at 9:09 AM, Gary Palmer <gpalmer at freebsd.org> wrote:

On Tue, Apr 15, 2014 at 08:25:51AM -0400, Jason Breitman wrote:
> I have not received a reply to my question and wanted to post again so that the group could see the question again.
> 

Are there any open files on the filesystem?  fstat or lsof should tell you,
I think.

Files thare are open but that have been deleted show up in df but not du.
That is not unique to zfs.

If there are no open files I'm not sure what else to suggest.  Does a scrub
pass OK?

Regards,

Gary


> 
> 
> 
> On Mar 26, 2014, at 12:53 PM, Jason Breitman <jbreitman at zxcvm.com> wrote:
> 
> The different disk usage measurements are frequently discussed and most of the time snapshots are the source of confusion.
> I use refquota to avoid this confusion for user based file systems, but can not explain the below reports and hope you can help.
> 
> Why is there an ~18 GB difference between du and df / usedbydataset?
> I included additional information so that you can see that used = usedbysnapshots + usedbydataset and that there are no reservations.
> 
> # du -sh /tank/users/auser
> 5.1G	/tank/users/auser
> 
> # df -h /tank/users/auser
> Filesystem           Size    Used   Avail Capacity  Mounted on
> tank/users/auser     35G     23G     11G    66%    /tank/users/auser   
> 
> # zfs get usedbydataset tank/users/auser
> NAME               PROPERTY       VALUE   SOURCE
> tank/users/auser  usedbydataset  23.2G   -
> 
> # zfs get used,usedbysnapshots,usedbydataset tank/users/auser
> NAME               PROPERTY         VALUE     SOURCE
> tank/users/auser  used             63.9G     -
> tank/users/auser  usedbysnapshots  40.7G     -
> tank/users/auser  usedbydataset    23.2G     -
> 
> # zfs get refreservation,usedbyrefreservation tank/users/auser
> NAME               PROPERTY              VALUE          SOURCE
> tank/users/auser  refreservation        none           default
> tank/users/auser  usedbyrefreservation  0 
> 
> 
> OS: Freebsd 9.1
> 
> # zpool upgrade -v
> This system is currently running ZFS pool version 28.
> 
> The following versions are supported:
> 
> VER  DESCRIPTION
> ---  --------------------------------------------------------
> 1   Initial ZFS version
> 2   Ditto blocks (replicated metadata)
> 3   Hot spares and double parity RAID-Z
> 4   zpool history
> 5   Compression using the gzip algorithm
> 6   bootfs pool property
> 7   Separate intent log devices
> 8   Delegated administration
> 9   refquota and refreservation properties
> 10  Cache devices
> 11  Improved scrub performance
> 12  Snapshot properties
> 13  snapused property
> 14  passthrough-x aclinherit
> 15  user/group space accounting
> 16  stmf property support
> 17  Triple-parity RAID-Z
> 18  Snapshot user holds
> 19  Log device removal
> 20  Compression using zle (zero-length encoding)
> 21  Deduplication
> 22  Received properties
> 23  Slim ZIL
> 24  System attributes
> 25  Improved scrub stats
> 26  Improved snapshot deletion performance
> 27  Improved snapshot creation performance
> 28  Multiple vdev replacements
> 
> For more information on a particular version, including supported releases,
> see the ZFS Administration Guide.
> 
> # zfs upgrade -v
> The following filesystem versions are supported:
> 
> VER  DESCRIPTION
> ---  --------------------------------------------------------
> 1   Initial ZFS filesystem version
> 2   Enhanced directory entries
> 3   Case insensitive and filesystem user identifier (FUID)
> 4   userquota, groupquota properties
> 5   System attributes
> 
> For more information on a particular version, including supported releases,
> see the ZFS Administration Guide.
> 
> 
> 
> Jason Breitman
> jbreitman at zxcvm.com
> 
> 
> 
> 
> 
> 
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