ZFS / zpool size

[Stefan Esser]

Am 17.01.2012 16:47, schrieb Christer Solskogen:
> Hi!
> 
> I have a zpool called data, and I have some inconsistencies with sizes.
> 
> $ zpool iostat
>                capacity     operations    bandwidth
> pool        alloc   free   read  write   read  write
> ----------  -----  -----  -----  -----  -----  -----
> data        3.32T   761G    516     50  56.1M  1.13M
> 
> $ zfs list -t all
> NAME                            USED  AVAIL  REFER  MOUNTPOINT
> data                           2.21T   463G  9.06G  /data
> 
> Can anyone throw any light on this?

The ZFS numbers are 2/3 of the ZPOOL numbers for alloc.

This looks like a raidz1 over 3 drives. The ZPOOL command shows
disk blocks available and used (disk drive view), the ZFS command
operates on the file-system level and shows blocks used to hold
actual data or available for actual data (does not account for
RAID parity overhead).

> Is not free the same as AVAIL?

Avail should be 2/3 of free, but I guess there is some overhead
that reduces the number of available blocks.

> I do not have any zfs snapshots, but some filesystems are compressed.

Compression affects the ZPOOL and ZFS numbers in the same way, but  "zfs
list" and "df" will differ significantly for file-systems that
contain compressible data.

Regards, STefan