Date: Wed, 26 Mar 2014 12:53:11 -0400 From: Jason Breitman <jbreitman@zxcvm.com> To: fs@freebsd.org Subject: Differences in reporting by du df and usedbydataset Message-ID: <0D13866F-04ED-4572-B7C9-04DC806B6513@zxcvm.com> In-Reply-To: <B5AC73B9-B7D1-4698-9CB8-1000C1AF472B@zxcvm.com> References: <B5AC73B9-B7D1-4698-9CB8-1000C1AF472B@zxcvm.com>
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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 =3D = 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 =20= # 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=20 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@zxcvm.com
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