Strange ZFS pool failure after updating kernel v6->v13

[Yan V. Batuto]

Hello!

RAID-Z v6 works OK with 7.2-RELEASE, but it fails with recent 7.2-STABLE.
--------------------------------------------------
# zpool status bigstore
  pool: bigstore
 state: ONLINE
 scrub: scrub completed with 0 errors on Fri Jun  5 22:28:19 2009
config:

        NAME        STATE     READ WRITE CKSUM
        bigstore    ONLINE       0     0     0
          raidz1    ONLINE       0     0     0
            ad4     ONLINE       0     0     0
            ad6     ONLINE       0     0     0
            ad8     ONLINE       0     0     0
            ad10    ONLINE       0     0     0

errors: No known data errors
--------------------------------------------------
After cvsup to 7-STABLE, usual procedure of rebuilding kernel and
world, and reboot pool is failed.
It's quite strange that now pool consists of ad8, ad10, and again ad8,
ad10 drives instead of ad4, ad6, ad8, ad10.

I removed additional disk controller few weeks ago, so raid-z
originally was created as ad8+ad10+ad12+ad14, and then
it appeared to be ad4+ad6+ad8+ad10. It was not a trouble for zfs v6,
but, probably, something is wrong here in zfs v13.
--------------------------------------------------
# zpool status bigstore
pool: bigstore
 state: UNAVAIL
status: One or more devices could not be used because the label is missing
        or invalid.  There are insufficient replicas for the pool to continue
        functioning.
action: Destroy and re-create the pool from a backup source.
   see: http://www.sun.com/msg/ZFS-8000-5E
 scrub: none requested
config:

        NAME        STATE     READ WRITE CKSUM
        bigstore    UNAVAIL      0     0     0  insufficient replicas
          raidz1    UNAVAIL      0     0     0  insufficient replicas
            ad8     FAULTED      0     0     0  corrupted data
            ad10    FAULTED      0     0     0  corrupted data
            ad8     ONLINE       0     0     0
            ad10    ONLINE       0     0     0