How to boot from a zfs external disk?

[Eduardo Lemos de Sa]

Dear

A year ago, I installed 10.3-RELEASE in a internal notebook hard-drive (zfs
formated, with pool named "zeeroot"). Now, I moved this hard drive to a
case intending use it as a portable FreeBSD machine. In past, this hard
disk was a /dev/ada0 device and now, of course, it assumes a name /dev/da0.
When I tried to boot, the initial process is ok, but when partitions and
filesystem are supposed to be mounted, I got a error and a request to
specify from where I want to boot.
When I typed "?" to see avaliable options, I got the result ( a photo took
from my cell phone):

http://www.quimica.ufpr.br/edulsa/fig-boot-externalharddisk.jpg

 I tried several of them including:

zfs:zeeroot

Please, could you give some hint about to procedure?

Thanks in advance for your attention

Eduardo

PS.: /dev/ada0 is the actual internal hard disk on the machine wheres I
tried to boot. So, it is not a option

-- 
Eduardo Lemos de Sa
Professor Titular
Dep. Quimica da Universidade Federal do Paraná
fone: +55(41)3361-3300
fax:   +55(41)3361-3186