Fresh installation on top of a old system in ZFS

[Darren Pilgrim]

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