ZFS Install Guide

Introduction

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).

Disclaimers

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 install instructions below, a YouTube video ZFS install tutorial is now available:

Downloading the ISO (With ZFS)

In order for us to install Funtoo on ZFS, you will need an environment that provides the ZFS tools. Therefore we will download a customized version of SLAX with ZFS SBs (SLAX Bundle) already included.

This is just a file that when combined with SLAX, gives you those tools.

Name: SLAX-English-US-7.0.8-x86_64_ZFS.iso (229 MB)
Release Date: 2013-06-15
md5sum 358e4b3cbec9110de83e5d1779200eeb

Download SLAX 7.0.8 with ZFS

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.

fdisk (MBR 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.

Command (m for help): o ↵
Building a new DOS disklabel with disk identifier 0xbeead864.

This is a destructive operation. Make sure you really don't want anything on this disk.

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

Create Partition 1 (boot):

Command: n ↵
Partition type: ↵
Partition number: ↵
First sector: ↵
Last sector: +250M ↵

Create Partition 2 (ZFS):

Command: n ↵
Partition type: ↵
Partition number: ↵
First sector: ↵
Last sector: ↵

Command: t ↵
Partition number: 2 ↵
Hex code: bf ↵

Command: p ↵

Device Boot      Start         End      Blocks   Id  System
/dev/sda1            2048      514047      256000   83  Linux
/dev/sda2          514048  1953525167   976505560   bf  Solaris

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.

# gdisk /dev/sda

Command: x ↵
Expert command: z ↵
About to wipe out GPT on /dev/sda. Proceed?: y ↵
GPT data structures destroyed! You may now partition the disk using fdisk or other utilities.
Blank out MBR?: y ↵

This is a destructive operation. Make sure you really don't want anything on this disk.

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

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 ↵

Only make the above BIOS Boot Partition if you are using GRUB 2 on GPT. If you are using the extlinux bootloader, this partition is not necessary.

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 volume

Format your separate /boot partition:

# mkfs.ext2 /dev/sda1

Encryption (Optional)

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

# cryptsetup -c aes-xts-plain64 luksFormat /dev/sda2
# cryptsetup luksOpen /dev/sda2 vault_1

If you followed the manual GPT partitioning instructions, you should change /dev/sda2 to /dev/sda3.

Create the zpool

We will first create the pool. The pool will be named `rpool` 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 rpool /dev/sda2

If you followed the manual GPT partitioning instructions, you should change /dev/sda2 to /dev/sda3. If you are using encrypted root, then change /dev/sda2 to 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 rpool/ROOT
# zfs create -o mountpoint=/ rpool/ROOT/funtoo

Optional, but recommended dataset: /home
# zfs create -o mountpoint=/home rpool/HOME

Optional, portage tree, distfiles, and binary packages:
# zfs create rpool/FUNTOO
# zfs create -o mountpoint=/usr/portage -o compression=off rpool/FUNTOO/portage
# zfs create -o mountpoint=/usr/portage/distfiles rpool/FUNTOO/portage/distfiles
# zfs create -o mountpoint=/usr/portage/packages rpool/FUNTOO/portage/packages

Optional datasets: /usr/src, /var
# zfs create -o mountpoint=/usr/src rpool/FUNTOO/src
# zfs create -o mountpoint=/var rpool/FUNTOO/var

Create your swap zvol

Make your swap +1G greater than your RAM. An 8G machine would have 9G of SWAP (This is kinda big though).

# zfs create -o sync=always -o primarycache=metadata -o secondarycache=none -o volblocksize=4K -V 9G rpool/swap

Format your swap zvol

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

Last minute checks and touches

Check to make sure everything appears fine:

# zpool status
# zfs list

Copy the zpool.cache file to your new environment.

# mkdir -p /mnt/funtoo/etc/zfs
# cp /etc/zfs/zpool.cache /mnt/funtoo/etc/zfs

Make an empty mtab file

# touch /mnt/funtoo/etc/mtab

Now we will continue to install funtoo.

Installing Funtoo

Download and install the Funtoo stage3 and continue installation as normal.

Then chroot into your new funtoo environment:

# cd /mnt/funtoo

Make a directory for /boot
# mkdir /mnt/funtoo/boot

Mount your boot drive
# mount /dev/sda1 /mnt/funtoo/boot

Bind the kernel related directories
# mount --rbind /proc proc
# mount --rbind /dev dev
# mount --rbind /sys sys

Copy network settings
# cp /etc/resolv.conf etc/

chroot into your new funtoo environment
# env -i HOME=/root TERM=$TERM chroot . /bin/bash -l

Sync your tree
# emerge --sync

Kernel Configuration

The below configurations are the requirements for "Bliss Initramfs Creator". Some of these might not be needed for genkernel.

Tested with kernels 2.6.32 - 3.9.X

When you get up to the kernel, make sure that you disable the CFQ scheduler, and turn on No-op (It's the default one once you disable all schedulers). The reason for this is because ZFS has its own scheduler and the CFQ one conflicts with it. Go to your kernel config, and make sure you have the following: (there should be a /usr/src/linux symlink as well)

- Linux Kernel
ZLIB_INFLATE/DEFLATE must be compiled into the kernel (not as a module).
> ZLIB_INFLATE [=y], ZLIB_DEFLATE [=y]

General setup --->
> [*] Initial RAM filesystem and RAM disk (initramfs/initrd) support
  > () Initramfs source file(s)

Device Drivers --->
  > Generic Driver Options --->
  >> [*] Maintain a devtmpfs filesystem to mount at /dev
  >> [*] Automount devtmpfs at /dev, after the kernel mounted the rootfs

  # Only if you want to make an SRM
  > File systems --->
  >> Miscellaneous filesystems --->
  >>> <*> SquashFS 4.0 - Squashed file system support
  >>> [*] Squashfs XATTR support
  >>> [*] Include support for ZLIB compressed file systems
  >>> [*] Include support for LZO compressed file systems
  >>> [*] Include support for XZ compressed file systems

* All other drivers required to see your PATA/SATA drives must be compiled in.

- app-arch/cpio
- sys-apps/busybox
- sys-kernel/spl
- sys-fs/zfs
- sys-fs/zfs-kmod

For SRM creation:
- sys-fs/squashfs-tools

For LUKS support:
- sys-fs/cryptsetup

- Linux Kernel
Device Drivers --->
  [*] Multiple devices driver support (RAID and LVM) --->
  <*> Device mapper support
  <*> Crypt target support

  Cryptographic API --->
  <*> XTS support
  -*- AES cipher algorithms

Continue and compile/install your kernel:

# make bzImage modules
# make install
# make modules_install

Installing the ZFS userspace tools

# emerge -av zfs

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

# zpool status
# zfs list

If everything worked, continue.

Install the bootloader

GRUB 2

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 -av 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 grub2:

# grub-install --no-floppy /dev/sda

You should receive the following message

Installation finished. No error reported.

If not, then go back to the above checklist.

Create a boot symlink

We will create a boot symlink so that we can have "consistent" boot configurations without any errors.

# cd /boot
# ln -s . boot

You should now have a symlink called 'boot' inside /boot that points to /boot :).

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.

genkernel

# emerge -av sys-kernel/genkernel
# genkernel --zfs initramfs

Example: kernel name is: vmlinuz-3.8.5-ALL
initramfs name is: initramfs-genkernel-x86_64-3.8.5-ALL
/boot partition is: /dev/sda1 (on GPT)
pool name is: rpool

genkernel entries need verification grub.cfg:

set timeout=3
set default=0

# Funtoo
menuentry "Funtoo - 3.8.5" {
        insmod part_gpt
        insmod ext2

        set root=(hd0,gpt1)

        linux /vmlinuz-3.8.5-ALL real_root=ZFS=rpool/ROOT/funtoo dozfs=force
        initrd /initramfs-genkernel-x86_64-3.8.5-ALL
}

If you followed the way to set up a separate partition to boot of (/dev/sda1 in this guid) you need to modify the entries in your grub.cfg, since grub will now not search inside zfs:

set timeout=3
set default=0

# Funtoo
menuentry "Funtoo - 3.8.5" {  
  insmod zfs
  linux /vmlinuz-3.8.5-ALL real_root=ZFS=rpool/ROOT/funtoo dozfs=force
  initrd /initramfs-genkernel-x86_64-3.8.5-ALL
}

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>.img /boot

<kernel_name> is the name of what you selected in the initramfs creator, and the name of the outputted file. Once you do this just go to your bootloader config, and add it in there.

Example: Kernel name is: vmlinuz-3.8.5-ALL
initramfs name is: initrd-3.8.5-ALL.img
/boot partition is: /dev/sda1 (on GPT)
Encrypted partitions (If any, example: /dev/sda2, /dev/sdb3, /dev/sdc4)
Pool root is: rpool/ROOT/funtoo

grub.cfg:

set timeout=3
set default=0

# Funtoo
menuentry "Funtoo - 3.8.5" {
        insmod part_gpt
        insmod ext2

        set root=(hd0,gpt1)

        linux /vmlinuz-3.8.5-ALL root=rpool/ROOT/funtoo quiet refresh
        # Let's say you have 3 drives that are encrypted, and your pool (which also contains your root) is on here
        # linux /vmlinuz-3.8.5-ALL root=rpool/ROOT/funtoo enc_root=/dev/sda2,/dev/sdb3,/dev/sdc4 quiet
        initrd /initrd-3.8.5-ALL.img
}

We are using the 'refresh' option because the current cachefile that was generated in SLAX won't work when the system is live. We will generate a new cachefile on the fly. You will need to recreate the initramfs once you are in the system so that the initramfs can have the new cachefile inside of it!

Final configuration

Add the zfs tools to openrc

# rc-update add zfs boot

Add filesystems to /etc/fstab

# nano /etc/fstab

# <fs>                  <mountpoint>    <type>          <opts>          <dump/pass>
# Do not add the /boot line below if you are using whole-disk zfs
/dev/sda1               /boot           ext2            defaults        0 2
/dev/zvol/rpool/swap    none            swap            sw              0 0

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/rpool/swap

Export the zpool
# cd /
# zpool export rpool

Reboot
# 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

Recreate initramfs

After you restart your machine and your inside the live system, remake a new initrd if you are using "Bliss Initramfs Creator". This is because the old cachefile that was used inside SLAX won't work for booting (At least not the first time). Now that our system is up, we will recreate the cache.

# cd /opt/bliss-initramfs
# ./createInit

Pick your desired option

Once your initrd is made, move it to /boot
# mv initrd* /boot

Now edit grub.cfg and remove the "refresh" option
nano /boot/grub/grub.cfg

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 rpool@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 rpool/ROOT/funtoo@install