ZFS mirror boot

[cteam]

In light of the approaching 8.2 release I want to know how to upgrade my zfs mirror to v15 (Im kind of skeptical that after the update everything is going to work smoothly). In addition, I would like both of my drives to be bootable (i think i failed to set this up correctly the first time around). As of now I simply can only boot from the master disk, the other disk in the mirror is just "along for the ride" it seems (as i added the disk with a simple zfs command.)

this is what i have:

> gpart show
=>        34  1953525101  ad10  GPT  (932G)
          34         128     1  freebsd-boot  (64K)
         162     8388608     2  freebsd-swap  (4.0G)
     8388770  1945136365     3  freebsd-zfs  (928G)

> zpool list
NAME   SIZE   USED  AVAIL    CAP  HEALTH  ALTROOT
tank   920G  84.6G   835G     9%  ONLINE  -
> zpool status
  pool: tank
 state: ONLINE
status: The pool is formatted using an older on-disk format.  The pool can
	still be used, but some features are unavailable.
action: Upgrade the pool using 'zpool upgrade'.  Once this is done, the
	pool will no longer be accessible on older software versions.
 scrub: none requested
config:

	NAME        STATE     READ WRITE CKSUM
	tank        ONLINE       0     0     0
	  mirror    ONLINE       0     0     0
	    ad10p3  ONLINE       0     0     0
	    ad12    ONLINE       0     0     0

errors: No known data errors
> 

#fstab
/dev/gptid/26a53c2f-1217-11e0-bbee-1aa210044b06 none swap sw 0 0
linproc /compat/linux/proc/ linprocfs rw 0 0

I have a swap partition on one disk for crash dump, i figure if that disk were to die I could temporarily deal with the loss of a swap partition.

There is a small amount of free space on the second drive, couldn't i just install a bootloader to that drive as well?

can i do this with the following? :

Fixit# gpart add -b 34 -s 64k -t freebsd-boot ad1
Fixit# gpart bootcode -b /mnt2/boot/pmbr -p /mnt2/boot/gptzfsboot -i 1 ad1

I will likely not make any changes until update time.
cheers.