ZFS Drive space reserved by ZFS

I'm trying to find the answer, but with no luck. Maybe I can't write a proper question.

The example for my zpool working as mirror-0.

Code:
% zpool list
NAME    SIZE  ALLOC   FREE  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH  ALTROOT
work    928G   230G   698G         -     9%    24%  1.00x  ONLINE  -
The zpool uses two 928GiB drives (1TB).

Code:
% zfs list
NAME    USED  AVAIL  REFER  MOUNTPOINT
work    230G   669G   230G  /work
Code:
% df -h
Filesystem         Size    Used   Avail Capacity  Mounted on
work               899G    230G    669G    26%    /work
But df and zfs command says that the filesystem can use only 899GiB.

Where is the missing 29GiB?

For UFS I can use tunefs -m 0 to get available the whole drive space. How to get it useful in ZFS?
 
Back
Top