First use gpart to setup the disk partitions, in this set up we have 4 disks, ad4 ad6 ad8 ad10.

We have booted from mfsbsd boot cd from http://mfsbsd.vx.sk/.
First check for any existing partitions on the disks and remove them.

# gpart show
# gpart delete -i 2 ad4
# gpart delete -i 2 ad6
# gpart delete -i 2 ad8
# gpart delete -i 2 ad10
# gpart delete -i 1 ad10
# gpart delete -i 1 ad8
# gpart delete -i 1 ad4
# gpart delete -i 1 ad6
# gpart destroy ad4
# gpart destroy ad6
# gpart destroy ad8
# gpart destroy ad10

Now the disks are clean we will setup gpt on them.

# gpart show
# gpart create -s gpt /dev/ad4
# gpart create -s gpt /dev/ad6
# gpart create -s gpt /dev/ad8
# gpart create -s gpt /dev/ad10

fdisk them…

# echo "a 1" | fdisk -f - ad4
# echo "a 1" | fdisk -f - ad6
# echo "a 1" | fdisk -f - ad8
# echo "a 1" | fdisk -f - ad10

Now create a boot part on each disk:

# gpart add -t freebsd-boot -s 128 ad4
# gpart add -t freebsd-boot -s 128 ad6
# gpart add -t freebsd-boot -s 128 ad8
# gpart add -t freebsd-boot -s 128 ad10

Set the main partition on the disk for the zpool and set disk label:

# gpart add -t freebsd-zfs -s 278G -l disk00 ad4
# gpart add -t freebsd-zfs -s 278G -l disk01 ad6
# gpart add -t freebsd-zfs -s 278G -l disk02 ad8
# gpart add -t freebsd-zfs -s 278G -l disk03 ad10

# dd if=/dev/zero of=/dev/ad4p2 bs=512 count=560
# dd if=/dev/zero of=/dev/ad6p2 bs=512 count=560
# dd if=/dev/zero of=/dev/ad8p2 bs=512 count=560
# dd if=/dev/zero of=/dev/ad10p2 bs=512 count=560

Set the freebsd bootcode on the first partition.

# gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 ad4
# gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 ad6
# gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 ad8
# gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 ad10

Ok now we can create the zpool we will setup a raidz2 this time, the altroot is important so we don’t mount over our current system.

If you are running zpool v28 you must also set the cache file path

# zpool create -f -m none -o altroot=/mnt -o cachefile=/boot/zfs/zpool.cache data raidz2 gpt/disk00 gpt/disk01 gpt/disk02 gpt/disk03

Other wise if zpool v15 or older use this command.

# zpool create -f -m none -o altroot=/mnt data raidz2 gpt/disk00 gpt/disk01 gpt/disk02 gpt/disk03
# zpool status

Now create the filesystems for freebsd, most of these are optional.

# zfs create -o mountpoint=/ data/root
# zfs create -o mountpoint=/usr data/usr
# zfs create -o mountpoint=/var data/var
# zfs create -o mountpoint=/var/db data/var/db
# zfs create -o mountpoint=/tmp data/tmp
# zfs create -o mountpoint=/usr/home data/usr/home

Setup zvol swap space:

# zfs create -V 4G data/root/swap
# zfs set org.freebsd:swap=on data/root/swap
# zfs set checksum=off data/root/swap

Set data/root as the boot filesystem.

# zpool set bootfs=data/root data

At this point you extract a freebsd distro into /mnt.
Configure /boot/loader.conf and rc.conf

# echo 'zfs_load="YES"' >> /mnt/boot/loader.conf
# echo 'vfs.root.mountfrom="zfs:data/root"' >> /mnt/boot/loader.conf
# echo 'zfs_enable="YES"' >> /mnt/etc/rc.conf

Import and Export to make sure all changes are written to the disk and the copy the cache to the new pool.

# zpool export data

Again if you are using zpool v28 then add the cache file path

# zpool import -o altroot=/mnt -o cachefile=/boot/zfs/zpool.cache data

Other wise

# zpool import -o altroot=/mnt data
# cp /boot/zfs/zpool.cache /mnt/boot/zfs/

Now boot into full freebsd zfs system.