GPT boot with ZFS RAIDZ "ZFS: i/o error - all block copies unavailable"

[Merijn Verstraaten]

On Mon, 26 Oct 2009 01:31:46 +0100, Robert Noland <rnoland at freebsd.org>  
wrote:
>> After installing 8.0-RC1 (amd64) from USB stick this installation works
>> fine. If I csup to RELENG_8 (amd64) and compile + install world and  
>> kernel
>> booting from the ZFS fails. The initial installation I did just this, on
>> another attempt I ran "gpart bootcode -b /boot/pbmr -p /boot/gptzfsboot
>> adX" on all disks before rebooting to see if that had any effect. The  
>> end
>> result is the same. After rebooting the machine I get the following
>> prompt(s):
>>
>>          ZFS: i/o error - all block copies unavailable
>>          Invalid format
>>
>>          FreeBSD/i386 boot
>>          Default: tank:/boot/kernel/kernel
>>          boot:
>
> Could you type "status" at this point and tell what it shows?

If I type status at this point I get:

   pool: tank
   config:
       NAME    STATE
       tank   ONLINE
     raidz1   ONLINE
      ad4p3   ONLINE
      ad6p3   ONLINE
      ad8p3   ONLINE
     ad10p3   ONLINE

Which seems odd, since that's all the drives there are. So if it finds  
these it's already found all drives. My optimistic "Oh! I'll try and boot  
again" spirit was however crushed since it just results in the same error.

Kind regards,
Merijn