ZFS Install Guide
- This guide will only show you how to install Funtoo/ZFS on a 64 bit system!
- This guide is also using new technologies such as bliss-boot/initramfs/kernel. If you would like to use boot-update and or genkernel, please check out the ZFS Install Guide's Addendum.
- This guide is a work in progress.
In this guide we will show you how to install Funtoo on Native ZFS. The tutorial is meant to be an "overlay" over the Regular Funtoo Installation. Follow the normal guide during parts that are omitted.
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).
For a quick tour of ZFS and have a big picture of its common operations you can consult the page ZFS Fun.
As a companion to the installation instructions below, a YouTube video tutorial is now available:
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
Creating a bootable USB from ISO (From a Linux Environment)
Now we will download the iso, plug in our flash drive, and install sysresccd into the drive using the default sysresccd install script:
Download the iso to your home directory # cd ~/ # [Download ISO] Make a temporary directory to mount loop the iso # mkdir /tmp/loop Mount the iso # mount -o ro,loop ~/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.
|Warning:||Make sure the USB you want to use is unmounted before running the script, or it will fail. The script will partition, and mount your usb to /mnt/backup automatically.|
Booting the ISO
|Warning:||Select the "Alternate 64 bit kernel (altker64)" option in the System Rescue CD Boot Menu. 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.|
There are two ways to partition your disk: You can use your entire drive and let ZFS automatically partition it, or you can do it manually.
We will be showing you how to partition it manually because if you do so, 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 without any hassles 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
|Warning:||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 (swap):
Command: n ↵ Partition Number: ↵ First sector: ↵ Last sector: +4G ↵ Hex Code: 8200 ↵
|Note:||A rule of thumb for swap size is either 2 x RAM or RAM + 1.|
Create Partition 4 (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 8968191 4.0 GiB 8200 Linux swap 4 8968192 1048575966 495.7 GiB BF00 Solaris root Command: w ↵
Format your /boot partition
# mkfs.ext2 -m 1 /dev/sda1
If you want encryption, then create your encrypted vault(s) now by doing the following:
# cryptsetup luksFormat /dev/sda4 # cryptsetup luksOpen /dev/sda4 vault_1
|Warning:||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 4K sectors:
# zpool create -f -o ashift=12 -o cachefile= -O compression=lz4 -O normalization=formD -m none -R /mnt/funtoo tank /dev/sda4
|Important:||If you are using encrypted root, change /dev/sda4 to /dev/mapper/vault_1.|
If you have a previous pool that you would like to import, you can do: # zpool import -f -o cachefile= -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 (/). 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/ # zfs create -o mountpoint=/usr/src tank/funtoo/src # zfs create -o mountpoint=/usr/portage -o compression=off tank/funtoo/portage
Format your swap
# mkswap -f /dev/sda3 # swapon /dev/sda3
Now we will continue to install 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
Once you've extracted the stage3, do a few more preparations and chroot into your new funtoo environment:
Bind the kernel related directories # mount -t proc none proc # mount --rbind /dev dev # mount --rbind /sys sys Copy network settings # cp -f /etc/resolv.conf etc Make the zfs folder in 'etc' and copy your zpool.cache # mkdir etc/zfs # cp /etc/zfs/zpool.cache etc/zfs Chroot into Funtoo # env -i HOME=/root TERM=$TERM chroot . bash -l
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 our /boot is, so that it can place the files in there.
# <fs> <mountpoint> <type> <opts> <dump/pass> /dev/sda1 /boot ext2 defaults 0 2 /dev/sda3 none swap sw 0 0
You can follow the kernel instructions in the normal guide, or you can install a pre-configured/compiled kernel called bliss-kernel. This kernel already has the correct configurations for ZFS and a variety of other scenarios. It's a vanilla kernel from kernel.org without any external patches.
To install sys-kernel/bliss-kernel 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:  linux-3.12.13-KS.02 *
You should see a star next to the version you installed. In this case it was 3.12.13-KS.02. If it's not set, you can type eselect kernel set #.
Installing the ZFS userspace tools and kernel modules
# emerge 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.
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/sda3 Reboot # reboot
|Warning:||Do not export the zpool. Just reboot. ZFS's zpool.cache file is shared between reboots and exporting the pool will cause problems. Exporting the pool is only meant when you want to move the zpool from one machine to another.|
|Important:||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.
Forgot to reset password?
System Rescue CD
If you aren't using bliss-initramfs, then you can reboot back into your sysresccd and reset through there by mounting your drive, chrooting, and then typing passwd.
# zpool import -f -o cachefile= -R /mnt/funtoo tank # chroot /mnt/funtoo bash -l # passwd # exit # reboot
If you forgot to reset your password and are using bliss-initramfs, you can add the su option to your bootloader parameters and the initramfs will throw you into the rootfs of your drive. In there you can run 'passwd' and then type 'exit'. Once you type 'exit', the initramfs will continue to boot your system as normal.
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/funtoo/root@install
|Important:||For a detailed overview, presentation of ZFS' capabilities, as well as usage examples, please refer to the ZFS Fun page.|
Starting from scratch
If your installation has gotten screwed up for whatever reason and you need a fresh restart, you can do the following from sysresccd to start fresh:
Destroy the pool and any snapshots and datasets it has # zpool destroy -R -f tank This deletes the files from /dev/sda1 so that even after we zap, recreating the drive in the exact sector position and size will not give us access to the old files in this partition. # mkfs.ext2 /dev/sda1 # sgdisk -Z /dev/sda
Now start the guide again :).