You have an ad0 disk. Create one slice covering the entire disk:

''%%# fdisk -BI /dev/ad0%%''

Initialize the BSDlabel:

''%%# bsdlabel -wB /dev/ad0s1%%''

Edit your label and create a small (like 256MB-512MB) 'a' partition and
use the rest for the 'd' partition:

''%%# bsdlabel -e /dev/ad0s1%%''

Something like this will create 512MB 'a' partition and allocate the rest for the 'd' partition:

''%%# /dev/ad0s1:%%''\\ 
''%%8 partitions:%%''\\ 
''%%#     size     offset  fstype%%''\\ 
''%%  a:  1048576  16      unused%%''\\ 
''%%  c:  *        0       unused%%''\\ 
''%%  d:  *        *       unused%%''

The 'd' partition will be used for [[ZFS]]:

''%%# zpool create tank ad0s1d%%''

Create bootdir directory where the boot file system will be mounted:

''%%# mkdir /tank/bootdir%%''\\ 
''%%# ln -s bootdir/boot /tank/boot%%''

Create a UFS file system on /dev/ad0s1a and copy the /boot/ directory onto it:

''%%# newfs /dev/ad0s1a%%''\\ 
''%%# mount /dev/ad0s1a /tank/bootdir%%''\\ 
''%%# cp -Rp /boot /tank/bootdir/%%''

If the boot filesystem is already existing then make sure that /boot/zfs/zpool.cache still gets copied over.

Now don't forget to add zfs_load="YES" to /tank/boot/loader.conf.

Ok, you also need to tell your loader where your root file system is.
You can do it by adding:

''%%vfs.root.mountfrom="zfs:tank"%%''

to /tank/boot/loader.conf or you can create /tank/bootdir/etc/fstab file
with one entry only:

''%%tank    /    zfs    rw    0    0%%''

On your [[ZFS]] file system, your /etc/fstab (/tank/etc/fstab) should contains the line above and:

''%%/dev/ad0s1a    /bootdir    ufs    rw    1    1%%''

(and everything else, ie. your swap and other file systems)

At the end, set mount point to 'legacy' so [[ZFS]] won't try to mount it automatically:

''%%# zfs set mountpoint=legacy tank%%''

==== troubleshooting ====
  * Ensure /boot/zfs/zpool.cache is up to date on the boot filesystem
  * Set ''%%vfs.zfs.debug=1%%'' in the loader to see more ZFS debug messages to the console

==== Alternate way with GPT and full zfs (no UFS /boot) for 8.0-RELEASE ====

%%FreeBSD%% 8.0 and later have support for a full zfs-based system (i.e. without using an UFS /boot), so we can use the GPT partitioning scheme along with /boot/gptzfsboot. See lulf blog's entry:

[[https://web.archive.org/web/20100824022058/http://lulf.geeknest.org:80/blog/freebsd/Setting_up_a_zfs-only_system/]]

or

[[https://www.dan.me.uk/blog/2010/02/08/booting-from-zfs-raid056-in-freebsd-8-0-release/]]

==== Automated installation with GPT and full zfs for 8.0-RELEASE ====

You may try the mfsbsd SE amd64 ISO image with the "zfsinstall" script located at: http://mfsbsd.vx.sk/

==== Automated install with GPT and Full ZFS with PXE ====

PXE: [[https://web.archive.org/web/20180218111315/https://planet.freebsd.org/brd/2012/03/23/pxe-booting-freebsd-9/]]

Install: [[https://web.archive.org/web/20180218111315/https://planet.freebsd.org/brd/2012/05/08/scripted-install-of-freebsd-9/]]

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{{tag>Zfs}}