ZFSBootPartition [FreeBSD WIKI]

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====== Installing FreeBSD Root on ZFS using FreeBSD-ZFS partition in a FreeBSD MBR Slice ======

===== Creating a bootable ZFS Filesystem =====

  - Boot %%FreeBSD%% install DVD or USB Memstick

  - Choose Fixit option in sysinstall

  - Create MBR disk \\ \\ 

If you are installing on an New drive, you will need to create the MBR geometry first:

<code>
Fixit# gpart create -s mbr ad0
</code>

  - Create Slice using gpart\\ \\ 

This example already has two slices defined on the drive.

<code>
Fixit# gpart show ad0
=>       63  625142385  ad0  MBR  (289G)
         63  209712447    1  !7  (100G)
  209712510     417690    2  !136  (204M)
  210130200  415012248       - free -  (198G)
</code>

Create a third slice - gpart will use all the remaining space by default. Then create a BSD partition table on the new slice.

<code>
Fixit# gpart add -t freebsd ad0
ad0s3 added
Fixit# gpart create -s BSD ad0s3
ad0s3 created
</code>

And examine the result:

<code>
Fixit# gpart show ad0
=>       63  625142385  ad0  MBR  (289G)
         63  209712447    1  !7  (100G)
  209712510     417690    2  !136  (204M)
  210130200  415012248    3  freebsd  (198G)
</code>

<callout type="info">
**Note:**

Sizes and offsets are specified in sectors by default (1 sector is typically 512 bytes) but can have an 'M' and 'G' suffix to use MB or GB.
</callout>

  - Set partition active (Optional)\\ \\ 

Some BIOSes might require setting a Slice active.  Here we set partition 1 (the Windows Partiton) as the active partition.

<code>
Fixit# gpart set -a active -i 1 ad0
</code>

  - Create partitions (ad0s3a and ad0s3b)\\ \\ 

Note that partition order is important. It seems that zfsboot requires the freebsd-zfs partition to be the first, so make sure you add if first, before your swap partition.

<code>
Fixit# gpart show ad0s3
=>        0  415012248  ad0s3  BSD  (198G)
          0  415012248  ad0s3  - free -  (198G)
</code>

<code>
Fixit# gpart add -s 194G -t freebsd-zfs ad0s3
ad0s3a added
</code>

<code>
Fixit# gpart show ad0s3
=>        0  415012248  ad0s3  BSD  (198G)
  406631421          1         freebsd-zfs  (194G)
  406631421    8380827         - free -  (4.0G)
</code>

<code>
Fixit# gpart add -t freebsd-swap ad0s3
ad0s3b added
</code>

<code>
Fixit# gpart show ad0s3
=>        0  415012248  ad0s3  BSD  (198G)
          0  406631421      1  freebsd-zfs  (194G)
  406631421    8380827      2  freebsd-swap  (4.0G)
</code>

<callout type="info">
**Note:**

  - While a [[/RootOnZFS#ZFS_Swap_Volume|ZFS Swap Volume]] can be used instead of the freebsd-swap partition, crash dumps can't be created on the ZFS Swap Volume.
  - Sizes and offsets are specified in sectors by default (1 sector is typically 512 bytes) but can have an 'M' or 'G' suffix to use MB or GB.
</callout>

  - Load ZFS kernel module

<code>
Fixit# kldload /mnt2/boot/kernel/opensolaris.ko
Fixit# kldload /mnt2/boot/kernel/zfs.ko
</code>

  - Create ZFS Pool zroot

<code>
Fixit# mkdir /boot/zfs
Fixit# zpool create zroot /dev/ad0s3a
Fixit# zpool set bootfs=zroot zroot
</code>

<callout type="info">
**Note:**

zroot is the name of the ZFS Pool, it could be anything (i.e. tank, data, ...)
</callout>

  - Install boot Manager

<code>
Fixit# gpart bootcode -b /mnt2/boot/boot0 ad0
ad0 has bootcode
</code>

It's ok if you get an "unknown class" message here, but it you get "failed to install" or the like, you'll need to try again after making sure that nothing is mounted from /dev/ad0.

  - Install ZFS boot\\ \\ 

Export zroot, before installing boot code

<code>
Fixit# zpool export zroot
</code>

Install the boot1 stage:

<code>
Fixit# dd if=/mnt2/boot/zfsboot of=/tmp/zfsboot1 count=1
Fixit# gpart bootcode -b /tmp/zfsboot1 /dev/ad0s3
</code>

This may fail with an "operation not permitted" error message, since the kernel likes to protect critical parts of the disk. If this happens for you, run:

<code>
Fixit# sysctl kern.geom.debugflags=0x10
</code>

Install the boot2 zfs stage into the convienient hole in the ZFS filesystem on-disk format which is located just after the ZFS metadata (this is the seek=1024).

<code>
Fixit# dd if=/mnt2/boot/zfsboot of=/dev/ad0s3a skip=1 seek=1024
</code>

Import zroot to continue the install

<code>
Fixit# zpool import zroot
</code>

===== Installing FreeBSD to the ZFS filesystem =====
{{page>RootOnZFS/InstallingFreeBSD&nofooter&noeditbtn}}

===== Finish install =====

  - Create /etc/fstab

<code>
Fixit# cat << EOF > /zroot/etc/fstab
# Device			Mountpoint		FStype	Options		Dump	Pass#
/dev/ad0s3b			none			swap	sw		0	0
EOF
</code>

  - export LD_LIBRARY_PATH 

<code>
Fixit# export LD_LIBRARY_PATH=/mnt2/lib 
</code>

  - Unmount all zfs filesystems

<code>
Fixit# zfs unmount -a
</code>

  - Change mount points for zroot pool 

<code>
Fixit# zfs set mountpoint=legacy zroot
Fixit# zfs set mountpoint=/tmp zroot/tmp
Fixit# zfs set mountpoint=/usr zroot/usr
Fixit# zfs set mountpoint=/var zroot/var
</code>

  - Exit Fixit mode, and then sysinstall.  Remove the %%FreeBSD%% install DVD/Memstick and the system will boot using the ZFS root.