Difference between revisions of "ZFS Install Guide"

m (Create your swap zvol)
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== Installing Funtoo ==
== Installing Funtoo ==
[[Funtoo_Linux_Installation|Download and extract the Funtoo stage3 and continue installation as normal.]]
Then once you've extracted the stage3, chroot into your new funtoo environment:
=== Pre-Chroot ===
Go into the directory that you will chroot into
Go into the directory that you will chroot into
# ##i##cd /mnt/funtoo
# ##i##cd /mnt/funtoo
Mount your boot drive
Make a boot folder and mount your boot drive
# ##i##mount /dev/sda1 /mnt/funtoo/boot
# ##i##mkdir boot
# ##i##mount /dev/sda1 boot
[[Funtoo_Linux_Installation|Now download and extract the Funtoo stage3 ...]]
Once you've extracted the stage3, do a few more steps and chroot into your new funtoo environment:
Bind the kernel related directories
Bind the kernel related directories
# ##i##mount -t proc none /mnt/funtoo/proc
# ##i##mount -t proc none proc
# ##i##mount --rbind /dev /mnt/funtoo/dev
# ##i##mount --rbind /dev dev
# ##i##mount --rbind /sys /mnt/funtoo/sys
# ##i##mount --rbind /sys sys
Copy network settings
Copy network settings
# ##i##cp /etc/resolv.conf /mnt/funtoo/etc/
# ##i##cp -f /etc/resolv.conf etc
chroot into your new funtoo environment
Chroot into Funtoo
# ##i##env -i HOME=/root TERM=$TERM chroot /mnt/funtoo /bin/bash --login
# ##i##env -i HOME=/root TERM=$TERM chroot . bash -l
Place your mountpoints into your /etc/mtab file
== In Chroot ==
# ##i##cat /proc/mounts > /etc/mtab
Create a symbolic link to your mountpoints
# ##i##ln -sf /proc/mounts /etc/mtab
Sync your tree
Sync your tree

Revision as of 19:56, March 4, 2014


This tutorial will show you how to install Funtoo on ZFS (rootfs). This tutorial is meant to be an "overlay" over the Regular Funtoo Installation. Follow the normal installation and only use this guide for steps 2, 3, and 8.

Introduction to ZFS

Since ZFS is a new technology for Linux, it can be helpful to understand some of its benefits, particularly in comparison to BTRFS, another popular next-generation Linux filesystem:

  • On Linux, the ZFS code can be updated independently of the kernel to obtain the latest fixes. btrfs is exclusive to Linux and you need to build the latest kernel sources to get the latest fixes.
  • ZFS is supported on multiple platforms. The platforms with the best support are Solaris, FreeBSD and Linux. Other platforms with varying degrees of support are NetBSD, Mac OS X and Windows. btrfs is exclusive to Linux.
  • ZFS has the Adaptive Replacement Cache replacement algorithm while btrfs uses the Linux kernel's Last Recently Used replacement algorithm. The former often has an overwhelmingly superior hit rate, which means fewer disk accesses.
  • ZFS has the ZFS Intent Log and SLOG devices, which accelerates small synchronous write performance.
  • ZFS handles internal fragmentation gracefully, such that you can fill it until 100%. Internal fragmentation in btrfs can make btrfs think it is full at 10%. Btrfs has no automatic rebalancing code, so it requires a manual rebalance to correct it.
  • ZFS has raidz, which is like RAID 5/6 (or a hypothetical RAID 7 that supports 3 parity disks), except it does not suffer from the RAID write hole issue thanks to its use of CoW and a variable stripe size. btrfs gained integrated RAID 5/6 functionality in Linux 3.9. However, its implementation uses a stripe cache that can only partially mitigate the effect of the RAID write hole.
  • ZFS send/receive implementation supports incremental update when doing backups. btrfs' send/receive implementation requires sending the entire snapshot.
  • ZFS supports data deduplication, which is a memory hog and only works well for specialized workloads. btrfs has no equivalent.
  • ZFS datasets have a hierarchical namespace while btrfs subvolumes have a flat namespace.
  • ZFS has the ability to create virtual block devices called zvols in its namespace. btrfs has no equivalent and must rely on the loop device for this functionality, which is cumbersome.

The only area where btrfs is ahead of ZFS is in the area of small file efficiency. btrfs supports a feature called block suballocation, which enables it to store small files far more efficiently than ZFS. It is possible to use another filesystem (e.g. reiserfs) on top of a ZFS zvol to obtain similar benefits (with arguably better data integrity) when dealing with many small files (e.g. the portage tree).



This guide is a work in progress. Expect some quirks.


Since ZFS was really designed for 64 bit systems, we are only recommending and supporting 64 bit platforms and installations. We will not be supporting 32 bit platforms!

Video Tutorial

As a companion to the installation instructions below, a YouTube video tutorial is now available:


The video and guide are currently out of sync. The video has newer instructions. The guide needs to be updated.

Downloading the ISO (With ZFS)

In order for us to install Funtoo on ZFS, you will need an environment that already provides the ZFS tools. Therefore we will download a customized version of System Rescue CD with ZFS included.

Name: sysresccd-4.0.1_zfs_0.6.2.iso  (545 MB)
Release Date: 2014-02-25
md5sum 01f4e6929247d54db77ab7be4d156d85
Download System Rescue CD with ZFS

Creating a bootable USB from ISO (From a Linux Environment)

After you download the iso, you can do the following steps to create a bootable USB:

Make a temporary directory
# mkdir /tmp/loop

Mount the iso
# mount -o ro,loop /root/sysresccd-4.0.1_zfs_0.6.2.iso /tmp/loop

Run the usb installer
# /tmp/loop/usb_inst.sh

That should be all you need to do to get your flash drive working.

Booting the ISO


When booting into the ISO, Make sure that you select the "Alternate 64 bit kernel (altker64)". The ZFS modules have been built specifically for this kernel rather than the standard kernel. If you select a different kernel, you will get a fail to load module stack error message.

Creating partitions

There are two ways to partition your disk: You can use your entire drive and let ZFS automatically partition it for you, or you can do it manually.

We will be showing you how to partition it manually because if you partition it manually you get to create your own layout, you get to have your own separate /boot partition (Which is nice since not every bootloader supports booting from ZFS pools), and you get to boot into RAID10, RAID5 (RAIDZ) pools and any other layouts due to you having a separate /boot partition.

gdisk (GPT Style)

A Fresh Start:

First lets make sure that the disk is completely wiped from any previous disk labels and partitions. We will also assume that /dev/sda is the target drive.

# sgdisk -Z /dev/sda

This is a destructive operation and the program will not ask you for confirmation! Make sure you really don't want anything on this disk.

Now that we have a clean drive, we will create the new layout.

First open up the application:

# gdisk /dev/sda

Create Partition 1 (boot):

Command: n ↵
Partition Number: 
First sector: 
Last sector: +250M ↵
Hex Code: 

Create Partition 2 (BIOS Boot Partition):

Command: n ↵
Partition Number: 
First sector: 
Last sector: +32M ↵
Hex Code: EF02 ↵

Create Partition 3 (ZFS):

Command: n ↵
Partition Number: 
First sector: 
Last sector: 
Hex Code: bf00 ↵

Command: p ↵

Number  Start (sector)    End (sector)  Size       Code  Name
   1            2048          514047   250.0 MiB   8300  Linux filesystem
   2          514048          579583   32.0 MiB    EF02  BIOS boot partition
   3          579584      1953525134   931.2 GiB   BF00  Solaris root

Command: w ↵

Format your /boot partition

# mkfs.ext2 -m 1 /dev/sda1

Encryption (Optional)

If you want encryption, then create your encrypted vault(s) now by doing the following:

# cryptsetup luksFormat /dev/sda3
# cryptsetup luksOpen /dev/sda3 vault_1

On some machines, a combination of ZFS and LUKS has caused instability and system crashes.

Create the zpool

We will first create the pool. The pool will be named `tank` and the disk will be aligned to 4096 (using ashift=12)

# zpool create -f -o ashift=12 -o cachefile= -O compression=on -m none -R /mnt/funtoo tank /dev/sda3

If you are using encrypted root, change /dev/sda3 to /dev/mapper/vault_1.

If you have a previous pool that you would like to import, you can do a: zpool import -f -R /mnt/funtoo <pool_name>.

Create the zfs datasets

We will now create some datasets. For this installation, we will create a small but future proof amount of datasets. We will have a dataset for the OS (/), and your swap. We will also show you how to create some optional datasets: /home, /var, /usr/src, and /usr/portage.

Create some empty containers for organization purposes, and make the dataset that will hold /
# zfs create -p tank/funtoo
# zfs create -o mountpoint=/ tank/funtoo/root

Optional, but recommended datasets: /home
# zfs create -o mountpoint=/home tank/funtoo/home

Optional datasets: /usr/src, /usr/portage/{distfiles,packages}
# zfs create -o mountpoint=/usr/src tank/funtoo/src
# zfs create -o mountpoint=/usr/portage -o compression=off tank/funtoo/portage
# zfs create -o mountpoint=/usr/portage/distfiles tank/funtoo/portage/distfiles
# zfs create -o mountpoint=/usr/portage/packages tank/funtoo/portage/packages

Create your swap zvol

For modern machines that have greater than 4 GB of RAM, A swap size of 2G should be enough. However if your machine doesn't have a lot of RAM, the rule of thumb is either 2x the RAM or RAM + 1 GB.

For this tutorial we will assume that it is a newer machine and make a 2 GB swap.

# zfs create -o sync=always -o primarycache=metadata -o secondarycache=none -o volblocksize=4K -V 2G tank/swap

Format your swap zvol

# mkswap -f /dev/zvol/tank/swap
# swapon /dev/zvol/tank/swap

Now we will continue to install funtoo.

Installing Funtoo


Go into the directory that you will chroot into
# cd /mnt/funtoo

Make a boot folder and mount your boot drive
# mkdir boot
# mount /dev/sda1 boot

Now download and extract the Funtoo stage3 ...

Once you've extracted the stage3, do a few more steps and chroot into your new funtoo environment:

</console> Bind the kernel related directories

  1. ##i##mount -t proc none proc
  2. ##i##mount --rbind /dev dev
  3. ##i##mount --rbind /sys sys

Copy network settings

  1. ##i##cp -f /etc/resolv.conf etc

Chroot into Funtoo

  1. ##i##env -i HOME=/root TERM=$TERM chroot . bash -l


In Chroot

Create a symbolic link to your mountpoints
# ln -sf /proc/mounts /etc/mtab

Sync your tree
# emerge --sync

Add filesystems to /etc/fstab

Before we continue to compile and or install our kernel in the next step, we will edit the /etc/fstab file because if we decide to install our kernel through portage, portage will need to know where is your /boot so that it can place the files in there. We also need to update /etc/mtab so our system knows what is mounted. Edit /etc/fstab:

# <fs>                  <mountpoint>    <type>          <opts>          <dump/pass>

/dev/sda1               /boot           ext2            defaults        0 2
/dev/zvol/tank/swap     none            swap            sw              0 0

Kernel Configuration

To speed up this step, you can install "bliss-kernel" since it's already properly configured for ZFS and a lot of other configurations. The kernel is also compiled and ready to go. To install sys-kernel/bliss-kernel (package not on wiki - please add) type the following:

# emerge bliss-kernel

Now make sure that your /usr/src/linux symlink is pointing to this kernel by typing the following:

# eselect kernel list
Available kernel symlink targets:
[1]   linux-3.10.10-FB.01 *

You should see a star next to the bliss-kernel version you installed. In this case it was 3.10.10-FB.01. If it's not set, you can type eselect kernel set #.

Installing the ZFS userspace tools and kernel modules

Emerge sys-fs/zfs (package not on wiki - please add), sys-kernel/spl (package not on wiki - please add), and sys-fs/zfs-kmod (package not on wiki - please add):

# emerge zfs 

Check to make sure that the zfs tools are working, the zpool.cache file that you copied before should be displayed.

SPL stands for: Solaris Porting Layer
# zpool status
# zfs list

If everything worked, continue.

Install the bootloader


Before you do this, make sure this checklist is followed:

  • Installed kernel and kernel modules
  • Installed zfs package from the tree
  • /dev, /proc, /sys are mounted in the chroot environment

Once all this is checked, let's install grub2. First we need to enable the "libzfs" use flag so zfs support is compiled for grub2.

# echo "sys-boot/grub libzfs" >> /etc/portage/package.use

Then we will compile grub2:

# emerge grub

Once this is done, you can check that grub is version 2.00 by doing the following command:

# grub-install --version
grub-install (GRUB) 2.00

Now try to install sys-boot/grub (package not on wiki - please add):

# grub-install --recheck /dev/sda

You should receive the following message:

Installation finished. No error reported.

If not, then go back to the above checklist.


Before you do this, make sure the following checklist is followed:

  • /dev, /proc and /sys are mounted.
  • Installed the sys-fs/zfs (package not on wiki - please add) package from the tree.

Once the above requirements are met, LILO can be installed.

Now we will install Package:Lilo.

# emerge sys-boot/lilo

Once the installation of LILO is complete we will need to edit the /etc/lilo.conf file:



All that is left now is to install the bootcode to the MBR.

This can be accomplished by running:

# /sbin/lilo

If it is successful you should see:

Warning: LBA32 addressing assumed
Added Funtoo + *
One warning was issued

Create the initramfs

There are two ways to do this, you can use genkernel, or you can use my bliss initramfs creator. I will show you both.


# emerge sys-kernel/genkernel
# You only need to add --luks if you used encryption
# genkernel --zfs --luks initramfs

Bliss Initramfs Creator

If you are encrypting your drives, then add the "luks" use flag to your package.use before emerging:

# echo "sys-kernel/bliss-initramfs luks" >> /etc/portage/package.use

Now install the creator:

# emerge bliss-initramfs
Then go into the install directory, run the script as root, and place it into /boot:

# cd /opt/bliss-initramfs
# ./createInit
# mv initrd-<kernel_name> /boot

<kernel_name> is the name of what you selected in the initramfs creator, and the name of the outputted file.

Using boot-update

/boot on separate partition

If you created a separate non-zfs partition for boot then configuring boot-update is almost exactly the same as a normal install except that auto detection for root does not work. You must tell boot-update what your root is.


If your using genkernel you must add 'real_root=ZFS=<root>' and 'dozfs' to your params. Example entry for /etc/boot.conf:

"Funtoo ZFS" {
        kernel vmlinuz[-v]
        initrd initramfs-genkernel-x86_64[-v]
        params real_root=ZFS=tank/os/funtoo/root
        params += dozfs=force
        # Also add 'params += crypt_root=/dev/sda3' if you used encryption
        # Adjust the above setting to your system if needed

Bliss Initramfs Creator

If you used the Bliss Initramfs Creator then all you need to do is add 'root=<root>' to your params. Example entry for /etc/boot.conf:

"Funtoo ZFS" {
        kernel vmlinuz[-v]
        initrd initrd[-v]
        params root=tank/os/funtoo/root quiet
        # If you have an encrypted device with a regular passphrase,
        # you can add the following line
        params += enc_root=/dev/sda3 enc_type=pass

After editing /etc/boot.conf, you just need to run boot-update to update grub.cfg

# boot-update

/boot on ZFS

TBC - pending update to boot-update to support this

Final configuration

Add the zfs tools to openrc

# rc-update add zfs boot

Clean up and reboot

We are almost done, we are just going to clean up, set our root password, and unmount whatever we mounted and get out.

Delete the stage3 tarball that you downloaded earlier so it doesn't take up space.
# cd /
# rm stage3-latest.tar.xz

Set your root password
# passwd
>> Enter your password, you won't see what you are writing (for security reasons), but it is there!

Get out of the chroot environment
# exit

Unmount all the kernel filesystem stuff and boot (if you have a separate /boot)
# umount -l proc dev sys boot

Turn off the swap
# swapoff /dev/zvol/tank/swap

Export the zpool
# cd /
# zpool export tank

# reboot

Don't forget to set your root password as stated above before exiting chroot and rebooting. If you don't set the root password, you won't be able to log into your new system.

and that should be enough to get your system to boot on ZFS.

After reboot

Create initial ZFS Snapshot

Continue to set up anything you need in terms of /etc configurations. Once you have everything the way you like it, take a snapshot of your system. You will be using this snapshot to revert back to this state if anything ever happens to your system down the road. The snapshots are cheap, and almost instant.

To take the snapshot of your system, type the following:

# zfs snapshot -r tank@install

To see if your snapshot was taken, type:

# zfs list -t snapshot

If your machine ever fails and you need to get back to this state, just type (This will only revert your / dataset while keeping the rest of your data intact):

# zfs rollback tank/os/funtoo/root@install

For a detailed overview, presentation of ZFS' capabilities, as well as usage examples, please refer to the ZFS Fun page.