mountroot prompt with error2, when trying to boot from a single drive in a 2-way mirror

[Fabian Keil]

Yudi V <yudi.tux at gmail.com> wrote:

> I checked some popular image hosting websites, could not find any that did
> not use javascript. I can send you the images via email.

Sure.

> This is reproducible on a clean install of 9.3 as well. I think it's a bug.

I think the problem could be that two of the labels from ada2p3 are picked
up when looking at ada2 itself. Quoting the gptzfsboot man page:

| After a disk is probed and gptzfsboot determines that the
| whole disk is not a ZFS pool member, the individual partitions 
| are probed in their partition table order.

Putting the pool on p2 and using p3 for swap would probably work around
this, but given that there's free space behind p3 already, it's not
obvious to me why this wasn't already sufficient.

> Here's the output of zdb -l /dev/ada2p3
[...] 
> 
> gpart show ada2 output:
> 
> =>       34  156301421  ada2  GPT  (74G)
>          34       2014        - free -  (1M)
>        2048        512     1  freebsd-boot  (256k)
>        2560       1536        - free -  (768k)
>        4096    8388608     2  freebsd-swap  (4.0G)
>     8392704   10485760        - free -  (5.0G)
>    18878464  137422848     3  freebsd-zfs  (65G)
>   156301312        143        - free -  (71k)

For comparison, no labels are found with this layout
(p3, p4 and p5 are also encrypted, though):

[fk at kendra ~]$ gpart show
=>        40  1250263648  ada0  GPT  (596G)
          40         128     1  freebsd-boot  (64K)
         168        1880        - free -  (940K)
        2048      409600     2  freebsd-zfs  (200M)
      411648     8388608     3  freebsd-zfs  (4.0G)
     8800256     8388608     4  freebsd-swap  (4.0G)
    17188864  1233074816     5  freebsd-zfs  (588G)
  1250263680           8        - free -  (4.0K)

[fk at kendra ~]$ zdb -l /dev/ada0
--------------------------------------------
LABEL 0
--------------------------------------------
failed to unpack label 0
--------------------------------------------
LABEL 1
--------------------------------------------
failed to unpack label 1
--------------------------------------------
LABEL 2
--------------------------------------------
failed to unpack label 2
--------------------------------------------
LABEL 3
--------------------------------------------
failed to unpack label 3

Fabian
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