ZFS and disk usage

[Volodymyr Kostyrko]

Mark Schouten wrote:
> Hi,
>
> I'm having some issues with a FreeBSD box using ZFS to serve iscsi to other boxes.
>
> [root at storage ~]# zpool list
> NAME      SIZE   USED  AVAIL    CAP  HEALTH  ALTROOT
> storage  1.77T   431G  1.34T    23%  ONLINE  -
>
> As you can see, the zpool is at only 23% of it's capacity. However, if you get a list of filesystems with "zfs list", you see that there is only 138GB free space left.
> [root at storage ~]# zfs list
> NAME                                    USED  AVAIL  REFER  MOUNTPOINT
> storage                                1.60T   138G   431G  /storage
> storage/ZFS_FS_1                         20G   158G    16K  -
> storage/ZFS_FS_2                         20G   158G    16K  -
> storage/ZFS_FS_3                        100G   238G    16K  -
> storage/ZFS_FS_4                         20G   158G    16K  -
> storage/ZFS_FS_5                          1G   139G    16K  -
> storage/ZFS_FS_6                        400G   538G    16K  -
> storage/ZFS_FS_7                         20G   158G    16K  -
> storage/ZFS_FS_8                        400G   538G    16K  -
> storage/ZFS_FS_9                         20G   158G    16K  -
> storage/ZFS_FS_10                        20G   158G    16K  -
> storage/ZFS_FS_11                        20G   158G    16K  -
> storage/ZFS_FS_12                       150G   288G    16K  -
> storage/ZFS_FS_13                        20G   158G    16K  -
>
> These are fiesystems that are created with the following command.
> zfs create -V ${size}GB ${ZFS_ROOT}/${diskname}

`zfs create -V` withous `-s` creates reserved volume that eats all 
needed space immediately. Technically zfs pool is filled only for 23%, 
but logically you have only 138G left unassigned.

-- 
Sphinx of black quartz judge my vow.