Fresh installation on top of a old system in ZFS

[Ross Penner]

On Sat, 22 Feb 2014, at 02:36 PM, Darren Pilgrim wrote:
> On 2/22/2014 12:11 PM, Ross Penner wrote:
> > I'm hoping to get some guidance on the best way to create a fresh
> > FreeBSD install using my existing drives partitioned with ZFS.
> >
> > The old set up is with two drives of different sizes. The smaller one is
> > mirrored with a partition of equal size on the larger drive to create
> > one pool which is the root and boot partition. A second pool is made of
> > the remaining space on the larger drive mounted at /tank/
> >
> > I booted the USB image of FreeBSD 10 and I couldn't see an obvious way
> > to use my old partitions as the base for the new system. Any advice that
> > could be offered would be really appreciated!
> 
> What does your ZFS dataset structure look like?  If your root is not the 
> base dataset, you can install the new OS in parallel, change the bootfs 
> and mountpoints and boot into the new OS leaving the old one untouched. 
>   For example, on a system that's been upgraded from 9.x to 10.x:
> 
> # zfs list -o name,mountpoint
> NAME                     MOUNTPOINT
> tank                     none
> tank/home                /home
> tank/logs                /var/log
> tank/mail                /var/mail
> tank/osroot9             none
> tank/osroot9/tmp         none
> tank/osroot9/usr         none
> tank/osroot9/usr/local   none
> tank/osroot9/usr/obj     none
> tank/osroot9/usr/src     none
> tank/osroot9/var         none
> tank/osroot9/var/empty   none
> tank/osroot9/var/tmp     none
> tank/osroot10            /
> tank/osroot10/tmp        /tmp
> tank/osroot10/usr        /usr
> tank/osroot10/usr/local  /usr/local
> tank/osroot10/usr/obj    /usr/obj
> tank/osroot10/usr/src    /usr/src
> tank/osroot10/var        /var
> tank/osroot10/var/empty  /var/empty
> tank/osroot10/var/tmp    /var/tmp
> tank/ports               /usr/ports
> tank/db/postgresql       /usr/local/pgsql
> tank/samba               /samba
> tank/www                 /usr/local/www
> 

I think I need to add some clarity about my setup. I had a mini-itx all
in one system that died on me. I bought a replacement system and
attached the same harddrives. The system boots and the ZFS filesystems
are available.

I have two zpools. zroot which is mounted root and tank which was
mounted at /tank.

I'm trying to follow this
(http://freebsdwiki.net/index.php/ZFS,_booting_from) guide, but my
importing my zpools instead of creating them.

The pools function fine when I boot off the harddrives, but I can't seem
to import them from the shell. 'zpool import -f -o altroot=/mnt zroot'
returns errors saying that none of the file systems are loaded. The same
happens for tank.

Can anybody offer any insight?

Thanks