correct way to setup gmirror on 7.4?

[Tom Evans]

On Thu, Apr 28, 2011 at 4:43 PM, Pete French <petefrench at ingresso.co.uk> wrote:
> Is not the problem here that you are trying to GPT label a gmirrored disc ?
> If you instead gmirror two GPT partitions then the problem goes away
> doesnt it ? Thats how I set things up - use parititoning on the ohysical
> drives, and then put the mirroring into the partitions thus created.
> Works fine, and doesnt suffer from any of the afforementioned problems.
>
> -pete.

Is this simple to do? When I setup my home ZFS server, I couldn't get
it to boot from ZFS, so I configured 2 disks as 'boot' discs:

=>        34  2930277101  ada5  GPT  (1.4T)
          34         128     1  (null)  (64K)
         162    12582912     2  root  (6.0G)
    12583074  2917694061     3  samsung15-1  (1.4T)

The other 'boot' disc is configured the same, except it has
altroot/samsung15-2 labels on the UFS/ZFS GPT partitions (the other 4
discs have a corresponding 6 GB partition for swap/dumps).

However, this is as far as I got. I currently have
vfs.root.mountfrom="ufs:/dev/gpt/root", and I'd like to gmirror 'root'
onto 'altroot', without overwriting GPT labels or anything dangerous!

Cheers

Tom