zfs: df and zpool list report different size

Barry Pederson bp at barryp.org
Thu Apr 26 15:01:38 UTC 2007

Alexandre Biancalana wrote:
> Hi list,
> I update one machine to -CURRENT (yesterday), and now I'm creating zfs
> filesystem using the following devices:
> ad9: 305245MB <Seagate ST3320620AS 3.AAE> at ata4-slave SATA150
> ad11: 305245MB <Seagate ST3320620AS 3.AAE> at ata5-slave SATA150
> Next I created the pool:
> # zpool create backup raidz ad9 ad11
> # mount
> /dev/ad8s1a on / (ufs, local)
> devfs on /dev (devfs, local)
> backup on /backup (zfs, local)
> # df -h
> Filesystem     Size    Used   Avail Capacity  Mounted on
> /dev/ad8s1a     72G    2.2G     64G     3%    /
> devfs          1.0K    1.0K      0B   100%    /dev
> backup         293G      0B    293G     0%    /backup
> # zpool list
> NAME                    SIZE    USED   AVAIL    CAP  HEALTH     ALTROOT
> backup                  596G    222K    596G     0%  ONLINE     -
> My doubt is why zpool list and df -h report different size ? Which of then
> is correct and should I trust  ?

The zpool size is correct in totalling up the usable size on the pool's 
drives, but it's not telling you how much is taken up by redundancy, so 
it's probably not a useful number to you.

The "df -h" is also correct and probably more useful.  "zfs list" should 
show a similar useful number.


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