Mounting from zfs failed with error 22 with gmirror

[Daniel Gerzo]

Hello list,

I have come across this thing and I don't have an idea what to do next.

I have this partition setup:

[root at rescue ~]# gpart show
=>        34  3907029101  ada0  GPT  (1.8T)
           34           6        - free -  (3.0k)
           40        1024     1  freebsd-boot  (512k)
         1064    83886080     2  freebsd-swap  (40G)
     83887144  3823141984     3  freebsd-zfs  (1.8T)
   3907029128           7        - free -  (3.5k)

=>        34  3907029101  ada1  GPT  (1.8T)
           34           6        - free -  (3.0k)
           40        1024     1  freebsd-boot  (512k)
         1064    83886080     2  freebsd-swap  (40G)
     83887144  3823141984     3  freebsd-zfs  (1.8T)
   3907029128           7        - free -  (3.5k)

[root at rescue ~]# gpart show -l
=>        34  3907029101  ada0  GPT  (1.8T)
           34           6        - free -  (3.0k)
           40        1024     1  boot0  (512k)
         1064    83886080     2  swap0  (40G)
     83887144  3823141984     3  sys0  (1.8T)
   3907029128           7        - free -  (3.5k)

=>        34  3907029101  ada1  GPT  (1.8T)
           34           6        - free -  (3.0k)
           40        1024     1  boot1  (512k)
         1064    83886080     2  swap1  (40G)
     83887144  3823141984     3  sys1  (1.8T)
   3907029128           7        - free -  (3.5k)
[root at rescue ~]# zpool import -f -o altroot=/mnt -o 
cachefile=/boot/zfs/zpool.cache sys
[root at rescue ~]# zpool status
   pool: sys
  state: ONLINE
   scan: none requested
config:

     NAME          STATE     READ WRITE CKSUM
     sys           ONLINE       0     0     0
       mirror-0    ONLINE       0     0     0
         gpt/sys0  ONLINE       0     0     0
         gpt/sys1  ONLINE       0     0     0

errors: No known data errors
[root at rescue ~]# zdb
sys:
     version: 28
     name: 'sys'
     state: 0
     txg: 13622
     pool_guid: 13749191682008517984
     hostid: 966392425
     hostname: 'rescue'
     vdev_children: 1
     vdev_tree:
         type: 'root'
         id: 0
         guid: 13749191682008517984
         children[0]:
             type: 'mirror'
             id: 0
             guid: 10821644781744913225
             metaslab_array: 30
             metaslab_shift: 34
             ashift: 12
             asize: 1957443928064
             is_log: 0
             create_txg: 4
             children[0]:
                 type: 'disk'
                 id: 0
                 guid: 12516881521540558071
                 path: '/dev/gpt/sys0'
                 phys_path: '/dev/gpt/sys0'
                 whole_disk: 1
                 create_txg: 4
             children[1]:
                 type: 'disk'
                 id: 1
                 guid: 187152467666907385
                 path: '/dev/gpt/sys1'
                 phys_path: '/dev/gpt/sys1'
                 whole_disk: 1
                 create_txg: 4
[root at rescue ~]# zpool get bootfs sys
NAME  PROPERTY  VALUE             SOURCE
sys   bootfs    sys/default/root  local
[root at rescue ~]# gmirror status
        Name    Status  Components
mirror/swap  COMPLETE  ada1p2 (ACTIVE)
                        ada0p2 (ACTIVE)

The problem is that while I do not load geom_mirror from loader.conf, 
the machine boots fine, however as soon as I enable gmirror in 
loader.conf the machine doesn't boot and errors with

/Trying to mount root from zfs:sys/default/root [].../

/Mounting from zfs:sys/default/root failed with error 22.
/


and it hangs in the prompt asking me to enter device to mount root from.

I found only this 
http://lists.freebsd.org/pipermail/freebsd-current/2012-November/037910.html 
email where avg@ mentions that it might be a bug in his code, but no 
further followups. However that is almost a year ago and I got trapped 
by this on 9.2-RC4.

Could anyone possibly give me some hints? (Please keep in in cc: as I am 
not subscribed to fs@)

Thank you in advance!

Kind regards,
Daniel