ZFS can't mount filesystem

[Igor Zabelin]

Hi,

I have trouble with ZFS. One of set filesystems can't mount.
zpool scrub is not doing anything
ZFS reports an error when geting the properties.
SMART extended offline test for each disk completed without error.
It's possible to recover data? Mount ignoring errors?

FreeBSD 8.2-RELEASE 

ZFS reports an error when geting the properties.

# zfs get all tank/var

[skip normal output]
internal error: unable to get version property
internal error: unable to get utf8only property
internal error: unable to get normalization property
internal error: unable to get casesensitivity property
[skip normal output]

# zpool status -v tank
  pool: tank
 state: ONLINE
status: One or more devices has experienced an error resulting in data
        corruption.  Applications may be affected.
action: Restore the file in question if possible.  Otherwise restore the
        entire pool from backup.
   see: http://www.sun.com/msg/ZFS-8000-8A
 scrub: scrub stopped after 0h0m with 0 errors on Sat May  7 08:09:35 2011
config:

        NAME           STATE     READ WRITE CKSUM
        tank           ONLINE       0     0    36
          raidz1       ONLINE       0     0   144
            gpt/disk5  ONLINE       0     0     0
            gpt/disk6  ONLINE       0     0     0
            gpt/disk7  ONLINE       0     0     0

errors: Permanent errors have been detected in the following files:

        tank/var:<0x0>