gpt zfs raidz1 boot failure

[Chris Jones]

This actually made for an interesting bug, once I dug into it some more: 
http://www.freebsd.org/cgi/query-pr.cgi?pr=164861

If you build a zfs in degraded mode, it's not bootable. But if you build 
it normally, then remove a disk to put it in degraded mode, it is bootable.

Chris

On 2/4/2012 9:56 PM, Chris Jones wrote:
> I have a raidz1 in degraded mode, with only 1 disk available. When I 
> try to boot it, I get this:
>
> ZFS: can only boot from disk, mirror, raidz1, raidz2 and raidz3 vdevs
> ZFS: i/o error - all block copies unavailable
> ZFS: can't read MOS
> ZFS: unexpected object set type 0
> ...followed by a couple of attempts to load maxroot/boot/kernel/kernel.
>
> I've carefully followed the instructions at 
> http://wiki.freebsd.org/RootOnZFS/GPTZFSBoot/9.0-RELEASE -- except 
> that I'm starting with a degraded zfs so I can transition my data from 
> gmirror. Here's more system info:
>
> maxwell$ uname -a
> FreeBSD maxwell.cjones.org 9.0-RELEASE FreeBSD 9.0-RELEASE #0: Tue 
> Jan  3 07:15:25 UTC 2012     
> root at obrian.cse.buffalo.edu:/usr/obj/usr/src/sys/GENERIC  i386
>
> maxwell# gpart show ada2
> =>       34  488281183  ada2  GPT  (232G)
>          34        128     1  freebsd-boot  (64k)
>         162  488281055     2  freebsd-zfs  (232G)
>
> maxwell# zpool status
>   pool: maxroot
>  state: DEGRADED
> status: One or more devices has been taken offline by the administrator.
>         Sufficient replicas exist for the pool to continue functioning 
> in a
>         degraded state.
> action: Online the device using 'zpool online' or replace the device with
>         'zpool replace'.
>  scan: none requested
> config:
>
>         NAME                     STATE     READ WRITE CKSUM
>         maxroot                  DEGRADED     0     0     0
>           raidz1-0               DEGRADED     0     0     0
>             ada2p2               ONLINE       0     0     0
>             8747991784175675917  OFFLINE      0     0     0  was 
> /usr/bigfile
>
> errors: No known data errors
>
>
> The errors seem to indicate that it's getting to the first- and 
> second-stage bootstrap, but it's unable to load /boot/zfsloader; 
> correct? The first line of error text seems to indicate that the 
> bootstrap thinks my pool isn't a raidz1; but the output of zpool says 
> otherwise. Any thoughts?
>
> Chris