RootOnZFS [FreeBSD WIKI]

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<callout type="warning">
**Warning**
This document is largely outdated, and is preserved to serve as documentation for existing installations.

Start with the %%FreeBSD%% Handbook's [[https://docs.freebsd.org/en/books/handbook/zfs/|ZFS Chapter]] if you have not read it yet. For instructions on how to install root on ZFS, please see the %%FreeBSD%% Handbook's [[https://docs.freebsd.org/en/books/handbook/bsdinstall/|Installation chapter]].
</callout>

====== Root On ZFS ======

%%FreeBSD%% can be installed to a root [[ZFS]] filesystem (/), using several different methods.

===== Root on ZFS =====

%%FreeBSD%% can boot from a ZFS root using either a MBR formated disk or GPT formated disk.\\ \\ 

Requirements: \\ 
%%FreeBSD%% install image that contains the Livefs Fixit environment:

  * 8.0-RELEASE-{arch}-dvd1.iso
  * 8.0-RELEASE-{arch}-memstick.img

==== Using MBR Disk ====

The advantage of using a MBR disk is that you can still dual boot with other Operating Systems.

=== UFS /boot ===

This installation boots %%FreeBSD%% from UFS filesystem /boot filesystem, and then mounts %%FreeBSD%%-ZFS partition as the root filesystem (/).

[[RootOnZFS/UFSBoot|Installing FreeBSD Root on ZFS using UFS /boot]]

=== FreeBSD-ZFS partition in a FreeBSD MBR Slice ===

This installation boots %%FreeBSD%% directly from the %%FreeBSD%%-ZFS root filesystem (/). This installation requires the creation of a MBR formated disk.  The %%FreeBSD%%-ZFS partition is then created inside a %%FreeBSD%% slice.  To boot from the %%FreeBSD%%-ZFS root filesystem requires the installation of zfsboot bootcode on the %%FreeBSD%% slice and %%FreeBSD%%-ZFS partition.  It will also require the installation of a ZFS aware /boot/loader.

[[RootOnZFS/ZFSBootPartition|Installing FreeBSD Root on ZFS using FreeBSD-ZFS partition in a FreeBSD MBR Slice]]

=== FreeBSD MBR slice ===

This installation boots %%FreeBSD%% directly from the %%FreeBSD%%-ZFS root filesystem (/). This installation requires the creation of a MBR formated disk.  A %%FreeBSD%% filesystem is then created using a %%FreeBSD%% slice.  To boot from the %%FreeBSD%%-ZFS root filesystem requires the installation of zfsboot bootcode on the slice.  It will also require the installation of a ZFS aware /boot/loader.

[[RootOnZFS/ZFSBootSlice|Installing FreeBSD Root on ZFS using a FreeBSD MBR Slice]] (Work in Progress)

==== Using GPT Disk ====

The disadvantage of using a GPT disk is that you can't dual boot other Operating Systems using the /boot/pmbr and /boot/gptzfsboot code.  You may be able to boot multiple Operating Systems using a GPT aware Grub or Grub2 setup and a Hybrid GPT/MBR Installation.

=== Single Disk Pool ===
This installation boots %%FreeBSD%% from the a GPT disk.  This installation requires the creation of a GPT formated disk, %%FreeBSD%%-Boot partition and %%FreeBSD%%-ZFS partition.  To boot from the %%FreeBSD%%-ZFS partition, requires the installation of gptzfsboot into the %%FreeBSD%%-Boot partition.

[[RootOnZFS/GPTZFSBoot|Installing FreeBSD Root on ZFS using GPT]]

=== Mirror Pool ===

[[RootOnZFS/GPTZFSBoot/Mirror|Installing FreeBSD Root on ZFS (Mirror) using GPT]]

=== RAIDZ1 Pool ===

[[RootOnZFS/GPTZFSBoot/RAIDZ1|Installing FreeBSD Root on ZFS (RAIDZ1) using GPT]]

=== RAIDZ2 Pool ===

[[RootOnZFS/GPTZFSBoot/RAIDZ2|Installing FreeBSD Root on ZFS (RAIDZ2) using GPT]]

=== Note about 9.0-RELEASE ===

[[RootOnZFS/GPTZFSBoot/9.0-RELEASE|Installing FreeBSD 9.0-RELEASE Root on ZFS (Mirror) using GPT]]

==== Using VTOC8 Disk (sparc64) ====

For booting a sparc64 arch, the installation procedure of the boot-loader needs to be customized:

[[RootOnZFS/VTOC8ZFSBoot/9.x-RELEASE|Installing FreeBSD 9.x-RELEASE Root on ZFS (Mirror) using VTOC8]]

===== ZFS Tips =====

==== ZFS Tuning Guide ====

Review the ZFS Tuning Guide for hints on tuning ZFS for %%FreeBSD%%.
[[ZFSTuningGuide|ZFS Tuning Guide]]

==== ZFS Swap Volume ====

Creating a swap partition on the ZFS Filesystem using a ZFS Volume:

<code>
Fixit# zfs create -V 2G -o org.freebsd:swap=on -o checksum=off -o compression=off -o dedup=off -o sync=disabled -o primarycache=none zroot/swap
</code>

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

If there is no real memory available, the system might become unresponsive. To help mitigate this, consider raising the value of vm.v_free_severe (as well as vm.v_free_min and vm.v_free_target such that v_free_severe < v_free_min < v_free_target). For instance, on a system with 3GB of RAM, JohnNielsen was able to prevent a reproducible out-of-memory hang by setting vm.v_free_severe=7168.
</callout>

==== Alternate /etc/fstab ====

Instead of using vfs.root.mountfrom and setting mount points for /tmp, /usr and /var, create an /etc/fstab to mount each of the ZFS filesystems.  Using the example [[ZFS]] Filesystem created in this guide, the /etc/fstab would be:

<code>
# Device			Mountpoint		FStype	Options		Dump	Pass#
/dev/ad0s3b			none			swap	sw		0	0
zroot				/			zfs	rw,noatime	0	0
zroot/tmp			/tmp			zfs	rw,noatime	0	0
zroot/usr			/usr			zfs	rw,noatime	0	0
zroot/usr/home			/usr/home		zfs	rw,noatime	0	0
zroot/usr/ports		/usr/ports		zfs	rw,noatime	0	0
zroot/usr/ports/distfiles	/usr/ports/distfiles	zfs	rw,noatime	0	0
zroot/usr/ports/packages	/usr/ports/packages	zfs	rw,noatime	0	0
zroot/usr/src			/usr/src		zfs	rw,noatime	0	0
zroot/var			/var			zfs	rw,noatime	0	0
zroot/var/crash		/var/crash		zfs	rw,noatime	0	0
zroot/var/db			/var/db			zfs	rw,noatime	0	0
zroot/var/db/pkg		/var/db/pkg		zfs	rw,noatime	0	0
zroot/var/empty		/var/empty		zfs	ro		0	0
zroot/var/log			/var/log		zfs	rw,noatime	0	0
zroot/var/mail			/var/mail		zfs	rw,noatime	0	0
zroot/var/run			/var/run		zfs	rw,noatime	0	0
zroot/var/tmp			/var/tmp		zfs	rw,noatime	0	0
</code>

NOTE: Since zroot has it's mountpoint set to legacy, any zfs filesystem created on zroot will need to either be added to /etc/fstab or have it's mountpoint set.

===== Other Root on ZFS guides =====

  * [[ZFSOnRoot|Root on ZFS configuration with UFS /boot]] by AndrewThompson
  * [[http://blogs.freebsdish.org/lulf/2008/12/16/setting-up-a-zfs-only-system/|Root on ZFS configuration (gptzfsboot)]] by UlfLilleengen
  * [[http://www.keltia.net/howtos/zfsroot-freebsd8/|GPT Mirror and RAIDZ1 ZFS-only boot]] by OllivierRobert
  * [[http://www.keltia.net/howtos/mfsbsd-zfs91/|9.1 GPT/GELI/Mirror/RAIDZ1 ZFS-only boot]] by OllivierRobert
  * [[http://www.leidinger.net/blog/2011/05/03/another-root-on-zfs-howto-optimized-for-4k-sector-drives/|Another root-on-zfs HOWTO (optimized for 4k-sector drives)]] by AlexanderLeidinger
  * [[http://anonsvn.h3q.com/projects/freebsd-patches/wiki/manageBE|manageBE]] by Philipp Wuensche
  * [[http://forums.freebsd.org/showthread.php?t=31662|sysutils/beadm]] by vermaden - Solaris Live-Update like boot-environment implementation for %%FreeBSD%%
  * [[http://web.mr-happy.com/hackstuff/FreeBSD-ZFS.php|ZFS-Only FreeBSD]] by Jeff Blank
  * [[ZFSOnRootWithZFSboot|Root on ZFS configuration (zfsboot)]] by ScotHetzel (depreciated)
  * [[http://julipedia.meroh.net/2013/07/installing-freebsd-with-zfs-root-on.html|Installing FreeBSD with a ZFS root on a PowerMac G5]] by JulioMerino

If you know of any other Root on ZFS guides, either add them here if you have access or let me know about them.