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[[Category:Getting and installing Arch]]
 
[[Category:Getting and installing Arch]]
{{Article summary start}}
+
[[ja:ZFS に Arch Linux をインストール]]
{{Article summary text|This article describes the necessary procedures for installing Arch Linux onto a ZFS root filesystem.}}
+
{{Related articles start}}
{{Article summary heading|Related}}
+
{{Related|ZFS}}
{{Article summary wiki|ZFS}}
+
{{Related|Experimenting with ZFS}}
{{Article summary wiki|ZFS on FUSE}}
+
{{Related articles end}}
{{Article summary end}}
+
This article details the steps required to install Arch Linux onto a ZFS root filesystem.
  
This article details the steps required to install Arch Linux onto a root ZFS filesystem. This article supplements the [[Beginners' Guide]].
+
== Installation ==
  
==Installing archzfs==
+
See [[ZFS#Installation]] for installing the ZFS packages. If installing Arch Linux onto ZFS from the archiso, it would be easier to use the [[Unofficial user repositories#archzfs|archzfs]] repository.
  
Using the archzfs repository is highly recommended for effortless updates.
+
=== Embedding archzfs into archiso ===
  
{{warning|The ZFS packages are tied to the kernel version they were built against. This means it will not be possible to perform kernel updates until new packages (or package sources) are released by the ZFS package maintainer.}}
+
See [[ZFS#Embed_the_archzfs_packages_into_an_archiso|ZFS]] article.
  
{{note|1=This guide uses the unofficial archzfs repository hosted at http://demizerone.com/demz-repo-core. This repository is maintained by Jesus Alvarez and is signed with his PGP key: [http://pgp.mit.edu:11371/pks/lookup?op=vindex&search=0x5E1ABF240EE7A126 0EE7A126].}}
+
== Partition the destination drive ==
  
===Embedding archzfs into archiso===
+
Review [[Partitioning]] for information on determining the partition table type to use for ZFS. ZFS supports GPT and MBR partition tables.
See [[ZFS#Embed_the_archzfs_packages_into_an_archiso]].
 
  
===Using the archzfs repository===
+
ZFS manages its own partitions, so only a basic partition table scheme is required. The partition that will contain the ZFS filesystem should be of the type {{ic|bf00}}, or "Solaris Root".
Activate the required network connection and then edit {{ic|/etc/pacman.d/mirrorlist}} and configure the mirrors for pacman to use. Once that is done, edit {{ic|/etc/pacman.conf}} and add the archzfs repository:
+
 
 +
Drives larger than 2TB require a GPT partition table. GRUB on BIOS/GPT configurations require a small (1~2MiB) BIOS boot partition to embed its image of boot code.
 +
 
 +
Depending upon your machine's firmware or your choice of boot mode, booting may or may not require an EFI partition. On a BIOS machine (or a UEFI machine booting in legacy mode) EFI partition is not required. Consult [[Boot loaders]] for more info.
 +
 
 +
=== Partition scheme ===
 +
 
 +
Here is an example of a basic partition scheme that could be employed for your ZFS root install on a BIOS/MBR installation using GRUB:
 +
 
 +
{{bc|<nowiki>
 +
Part    Size  Type
 +
----    ----  -------------------------
 +
  1    XXXG  Solaris Root (bf00)</nowiki>
 +
}}
 +
 
 +
Using GRUB on a BIOS (or UEFI machine in legacy boot mode) machine but using a GPT partition table:
  
{{hc|# nano /etc/pacman.conf|<nowiki>
+
{{bc|<nowiki>
[demz-repo-core]
+
Part    Size  Type
Server = http://demizerone.com/$repo/$arch</nowiki>
+
----    ----  -------------------------
 +
  1      2M  BIOS boot partition (ef02)
 +
  2    XXXG  Solaris Root (bf00)</nowiki>
 
}}
 
}}
  
{{Note|You should change the repo name from 'demz-repo-core' to 'demz-repo-archiso' if you are using the standard Arch ISOs to install (didn't build your own, above)}}
+
Another example, this time using a UEFI-specific bootloader (such as [[rEFInd]]) and GPT:
  
Next, add the archzfs maintainer's PGP key to the local trust:
+
{{bc|<nowiki>
 +
Part    Size  Type
 +
----    ----  -------------------------
 +
  1    100M  EFI boot partition (ef00)
 +
  2    XXXG  Solaris Root (bf00)</nowiki>
 +
}}
  
{{bc|# pacman-key -r 0EE7A126
+
ZFS does not support swap files. If you require a swap partition, see [[ZFS#Swap volume]] for creating a swap ZVOL.
# pacman-key --lsign-key 0EE7A126}}
 
  
Finally, update the pacman databases and install archzfs:
+
{{Tip|Bootloaders with support for ZFS are described in [[#Install and configure the bootloader]].}}
 +
{{Warning|Several GRUB bugs ([https://savannah.gnu.org/bugs/?42861 bug #42861], [https://github.com/zfsonlinux/grub/issues/5 zfsonlinux/grub/issues/5]) complicate installing it on ZFS partitions, see [[#Install and configure the bootloader]] for a workaround}}
  
{{bc|# pacman -Syy}}
+
=== Example parted commands ===
 +
Here are some example commands to partition a drive for the second scenario above ie using BIOS/legacy boot mode with a GPT partition table and a (slighty more than) 1MB BIOS boot partition for GRUB:
  
This is also the best time to install your favorite text editor, otherwise nano or vi will have to be used.
+
# parted /dev/sdx
 +
(parted)mklabel gpt
 +
(parted)mkpart non-fs 0% 2
 +
(parted)mkpart primary 2 100%
 +
(parted)set 1 bios_grub on
 +
(parted)set 2 boot on
 +
(parted)quit
  
{{bc|# pacman -S archzfs dosfstools gptfdisk vim}}
+
You can achieve the above in a single command like so:
  
==Partition the destination drive==
+
parted --script /dev/sdx mklabel gpt mkpart non-fs 0% 2 mkpart primary 2 100% set 1 bios_grub on set 2 boot on
  
Review [[Beginners'_Guide#Prepare_the_storage_drive]] for information on determining the partition table type to use for ZFS. ZFS supports GPT and MBR partition tables.
+
If you are creating an EFI partition then that should have the boot flag set instead of the root partition.
  
ZFS manages its own partitions, so only a basic partition table scheme is required. The partition that will contain the ZFS filesystem should be of the type {{ic|bf00}}, or "Solaris Root".
+
== Format the destination disk ==
 +
 
 +
If you have opted for a boot partition as well as any other non-ZFS system partitions then format them. Do not do anything to the Solaris partition nor to the BIOS boot partition. ZFS will manage the first, and your bootloader the second.
  
===Partition scheme===
+
== Setup the ZFS filesystem ==
  
Here is an example, using MBR, of a basic partition scheme that could be employed for your ZFS root setup:
+
First, make sure the ZFS modules are loaded,
  
{{bc|<nowiki>Part    Size  Type
+
# modprobe zfs
----    ----  -------------------------
 
  1    512M  Ext boot partition (8300)
 
  2    XXXG  Solaris Root (bf00)</nowiki>}}
 
  
Here is an example using GPT. The BIOS boot partition contains the bootloader.
+
=== Create the root zpool ===
  
{{bc|<nowiki>Part    Size  Type
+
# zpool create -f zroot /dev/disk/by-id/''id-to-partition-partx''
----    ----  -------------------------
 
  1      2M  BIOS boot partition (ef02)
 
  1    512M  Ext boot partition (8300)
 
  2    XXXG  Solaris Root (bf00)</nowiki>}}
 
  
An additional partition may be required depending on your hardware and chosen bootloader. Consult [[Beginners'_Guide#Install_and_configure_a_bootloader]] for more info.
+
{{Warning|
 +
* Always use id names when working with ZFS, otherwise import errors will occur.
 +
* The zpool command will normally activate all features. See [[ZFS#GRUB-compatible pool creation]] when using [[GRUB]].}}
  
{{tip|Bootloaders with support for ZFS are described in [[#Install and configure the bootloader]].}}
+
=== Create your datasets ===
  
==Format the destination disk==
+
Instead of using conventional disk partitions, ZFS has the concept of datasets to manage your storage. Unlike disk partitions, datasets have no fixed size and allow for different attributes, such as compression, to be applied per dataset. Normal ZFS datasets are mounted automatically by ZFS whilst legacy datasets are required to be mounted using fstab or with the traditional mount command.
  
Format the boot partition as well as any other system partitions. Do not do anything to the Solaris partition nor to the BIOS boot partition. ZFS will manage the first, and your bootloader the second.
+
One of the most useful features of ZFS is boot environments. Boot environments allow you to create a bootable snapshot of your system that you can revert to at any time instantly by simply rebooting and booting from that boot environment. This can make doing system updates much safer and is also incredibly useful for developing and testing software. In order to be able to use [https://github.com/b333z/beadm beadm] to manage boot environments your datasets must be configured properly. Key to this are that you split your data directories (such as {{ic|/home}}) into datasets that are distinct from your system datasets and that you do not place data in the root of the pool as this cannot be moved afterwards.  
  
==Setup the ZFS filesystem==
+
You should always create a dataset for at least your root filesystem and in nearly all cases you will also want {{ic|/home}} to be in a separate dataset. You may decide you want your logs to persist over boot environments. If you are a running any software that stores data outside of {{ic|/home}} (such as is the case for database servers) you should structure your datasets so that the data directories of the software you want to run are separated out from the root dataset.
  
First, make sure the ZFS modules are loaded,
+
With these example commands, we will create a basic boot environment compatible configuration comprising of just root and {{ic|/home}} datasets with lz4 compression to save space and improve IO performance:
  
{{bc|# modprobe zfs}}
+
# zfs create -o mountpoint=none zroot/data
 +
# zfs create -o mountpoint=none zroot/ROOT
 +
# zfs create -o compression=lz4 -o mountpoint=/ zroot/ROOT/default
 +
# zfs create -o compression=lz4 -o mountpoint=/home zroot/data/home
  
===Create the root zpool===
+
=== Configure the root filesystem ===
  
{{bc|# zpool create zroot /dev/disk/by-id/<id-to-partition>}}
+
If you have just created your zpool, it will be mounted in a dir at the root of your tree named after the pool (ie /zroot). If the following set commands fail, you may need to unmount any ZFS filesystems first:
  
{{Warning|Always use id names when working with ZFS, otherwise import errors will occur.}}
+
# zfs umount -a
  
===Create necessary filesystems===
+
Now set the mount points of the datasets:
  
If so desired, sub-filesystem mount points such as /home and /root can be created with the following commands:
+
# zfs set mountpoint=/ zroot/ROOT/default
 +
# zfs set mountpoint=legacy zroot/data/home
  
{{bc|# zfs create zroot/home
+
{{Note|{{ic|/etc/fstab}} mounts occur before zfs mounts, so don't use zfs mountpoints on directories with subfolders configured to be mounted by {{ic|/etc/fstab}}.}}
# zfs create zroot/root}}
 
  
Note that if you want to use other datasets for system directories ( /var or /etc included ) your system will not boot unless they are listed in /etc/fstab!  We will address that at the appropriate time in this tutorial.
+
and put them in {{ic|/etc/fstab}}
 +
{{hc|/etc/fstab|
 +
# <file system>        <dir>        <type>    <options>              <dump> <pass>
 +
zroot/ROOT/default / zfs defaults,noatime 0 0
 +
zroot/data/home /home zfs defaults,noatime 0 0}}
  
<!-- Taken the following Swap info from https://wiki.archlinux.org/index.php/ZFS -->
+
All legacy datasets must be listed in {{ic|/etc/fstab}} or they will not be mounted at boot.
  
=== Swap partition ===
+
Set the bootfs property on the descendant root filesystem so the boot loader knows where to find the operating system.
  
ZFS does not allow the use swapfiles, but it is possible to use a ZFS volume as swap partition. It is important to set the ZVOL block size to match the system page size; for x86_64 systems that is 4k.
+
# zpool set bootfs=zroot/ROOT/default zroot
  
Create a 8gb (or whatever is required) ZFS volume:
+
Export the pool,
  
{{bc|# zfs create -V 8G -b 4K <pool>/swap}}
+
# zpool export zroot
  
Initialize and enable the volume as a swap partition:
+
{{Warning|Do not skip this, otherwise you will be required to use {{ic|-f}} when importing your pools. This unloads the imported pool.}}
 +
{{Note|This might fail if you added a swap partition. You need to turn it off with the ''swapoff'' command.}}
  
{{bc|# mkswap /dev/zvol/<pool>/swap
+
Finally, re-import the pool,
# swapon /dev/zvol/<pool>/swap}}
 
  
After using {{ic|pacstrap}} to install the base system, edit {{ic|/<root>/etc/fstab}} to ensure the swap partition is mounted at boot:
+
# zpool import -d /dev/disk/by-id -R /mnt zroot
  
{{bc|/dev/zvol/<pool>/swap none swap defaults 0 0}}
+
{{Note|{{ic|-d}} is not the actual device id, but the {{ic|/dev/by-id}} directory containing the symbolic links.
 +
If this command fails and you are asked to import your pool via its numeric ID, run {{ic|zpool import}} to
 +
find out the ID of your pool then use a command such as:
 +
{{ic|zpool import 9876543212345678910 -R /mnt zroot}}
 +
}}
  
Make sure to unmount all ZFS filesystems before rebooting the machine, otherwise any ZFS pools will refuse to be imported:
+
If there is an error in this step, you can export the pool to redo the command. The ZFS filesystem is now ready to use.
  
{{bc|# zfs umount -a}}
+
Be sure to bring the {{ic|zpool.cache}} file into your new system. This is required later for the ZFS daemon to start.
  
===Configure the root filesystem===
+
# cp /etc/zfs/zpool.cache /mnt/etc/zfs/zpool.cache
  
First, set the mount point of the root filesystem:
+
if you do not have {{ic|/etc/zfs/zpool.cache}}, create it:
  
{{bc|<nowiki># zfs set mountpoint=/ zroot</nowiki>}}
+
# zpool set cachefile=/etc/zfs/zpool.cache zroot
  
and optionally, any sub-filesystems:
+
== Install and configure Arch Linux ==
  
{{bc|<nowiki># zfs set mountpoint=/home zroot/home
+
Follow the following steps using the [[Installation guide]]. It will be noted where special consideration must be taken for ZFSonLinux.
# zfs set mountpoint=/root zroot/root</nowiki>}}
 
  
Set the bootfs property on the descendant root filesystem so the boot loader knows where to find the operating system.
+
* First mount any legacy or non-ZFS boot or system partitions using the mount command.
  
{{bc|<nowiki># zpool set bootfs=zroot zroot</nowiki>}}
+
* Install the base system.
  
Export the pool,
+
* The procedure described in [[Installation guide#Fstab]] is usually overkill for ZFS. ZFS usually auto mounts its own partitions, so we do not need ZFS partitions in {{ic|fstab}} file, unless the user made legacy datasets of system directories. To generate the {{ic|fstab}} for filesystems, use:
  
{{bc|# zpool export zroot}}
+
# genfstab -U -p /mnt >> /mnt/etc/fstab
  
{{Warning|Don't skip this, otherwise you will be required to use -f when importing your pools. This unloads the imported pool.}}
+
* Edit the {{ic|/etc/fstab}}:
{{Note|This might fail if you added a swap partition above. Need to turn it off with the ''swapoff'' command.}}
 
  
Finally, re-import the pool,
+
{{Note|
 +
* If you chose to create legacy datasets for system directories, keep them in this {{ic|fstab}}!
 +
* Comment out all non-legacy datasets apart from the root dataset, the swap file and the boot/EFI partition. It is a convention to replace the swap's uuid with {{ic|/dev/zvol/zroot/swap}}.
 +
}}
  
{{bc|# zpool import -d /dev/disk/by-id -R /mnt zroot}}
+
* You need to add the [[Unofficial_user_repositories#archzfs|Arch ZFS]] repository to {{ic|/etc/pacman.conf}}, sign its key and [[install]] '''zfs-linux''' (or '''zfs-linux-lts''' if you are running the LTS kernel) within the arch-chroot before you can update the ramdisk with ZFS support.
  
{{Note|"-d" is not the actual device id, but the /dev/by-id directory containing the symlinks.}}
+
* When creating the initial ramdisk, first edit {{ic|/etc/mkinitcpio.conf}} and add {{ic|zfs}} before filesystems. Also, move {{ic|keyboard}} hook before {{ic|zfs}} so you can type in console if something goes wrong. You may also remove fsck (if you are not using Ext3 or Ext4). Your {{ic|HOOKS}} line should look something like this:
 +
HOOKS="base udev autodetect modconf block keyboard zfs filesystems"
  
If there is an error in this step, you can export the pool to redo the command. The ZFS filesystem is now ready to use.
+
When using systemd in the initrd, you need to install {{AUR|mkinitcpio-sd-zfs}} and add the {{ic|sd-zfs}} hook after the {{ic|systemd}} hook instead of the {{ic|zfs}} hook. Keep in mind that this hook uses different kernel parameters than the default {{ic|zfs}} hook, more information can be found at the [https://github.com/dasJ/sd-zfs project page].
  
==Install and configure Arch Linux==
+
{{Note|
 +
* If you are using a separate dataset for {{ic|/usr}} and have followed the instructions below, you must make sure you have the {{ic|usr}} hook enabled after {{ic|zfs}}, or your system will not boot.
 +
}}
  
Follow the following steps using the [[Beginners' Guide]]. It will be noted where special consideration must be taken for ZFSonLinux.
+
* [[Regenerate the initramfs]].
  
* First mount any boot or system partitions using the mount command.
+
== Install and configure the bootloader ==
  
* Install the base system.
+
=== For BIOS motherboards ===
  
* The procedure described in [[Beginners' Guide#Generate an fstab]] is usually overkill for ZFS. ZFS usually auto mounts its own partitions, so we do not need ZFS partitions in fstab file, unless the user made datasets of system directories. To generate the fstab for filesystems, use: {{bc|<nowiki># genfstab -U -p /mnt | grep boot >> /mnt/etc/fstab</nowiki>}}
+
Install GRUB onto your disk as instructed here: [[GRUB#BIOS systems]]. {{ic|grub-mkconfig}} fails to properly generate entries for systems hosted on ZFS. Users can either attempt to correct the output of {{ic|grub-mkconfig}} or generate and edit {{ic|grub.cfg}} manually. The GRUB [https://www.gnu.org/software/grub/manual/grub.html#Configuration manual] provides detailed information on manually configuring the software which you can supplement with [[GRUB]] and [[GRUB/Tips and tricks]].
  
*Edit the /etc/fstab:
+
When booting from ZFS, kernel and initrd paths have to be in the following format:
  
{{Note|If you chose to create datasets for system directories, Keep them in this fstab! Comment out the lines for the '/', '/root', and '/home' mountpoints, rather than deleting them.  You may need those UUIDs later if something goes wrong.}}  
+
  /dataset/@/actual/path  
  
{{Note|Anyone who just stuck with the guide's directions can delete everything except for the swap file and the boot/EFI partition.  It seems convention to replace the swap's uuid with '/dev/zvol/zroot/swap'}}
+
Example with Arch installed on the root dataset:
  
 +
{{hc|/boot/grub/grub.cfg|<nowiki>
 +
set timeout=5
 +
set default=0
  
* When creating the initial ramdisk, first edit {{ic|/etc/mkinitcpio.conf}} and add {{ic|zfs}} before filesystems. Also, move {{ic|keyboard}} hook before {{ic|zfs}} so you can type in console if something goes wrong. You may also remove fsck (if you are not using Ext3 or Ext4). Your HOOKS line should look something like this:{{bc|<nowiki>HOOKS="base udev autodetect modconf block keyboard zfs filesystems"</nowiki>}}
+
menuentry "Arch Linux" {
 +
    search -u UUID
 +
    linux /@/boot/vmlinuz-linux zfs=zroot rw
 +
    initrd /@/boot/initramfs-linux.img
 +
}
 +
</nowiki>}}
  
* Regenerate the initramfs with the command: {{bc|# mkinitcpio -p linux}}
+
Example with Arch installed on a nested dataset:
  
==Install and configure the bootloader==
+
{{hc|/boot/grub/grub.cfg|<nowiki>
 +
set timeout=5
 +
set default=0
  
===For BIOS motherboards===
+
menuentry "Arch Linux" {
 +
    search -u UUID
 +
    linux /ROOT/default/@/boot/vmlinuz-linux zfs=zroot/ROOT/default rw
 +
    initrd /ROOT/default/@/boot/initramfs-linux.img
 +
}
 +
</nowiki>}}
  
Follow [[Grub2#BIOS_systems_2]] to install grub onto your disk. {{ic|grub-mkconfig}} does not properly detect the ZFS filesystem, so it is necessary to edit {{ic|grub.cfg}} manually:
+
Example with a separate non-ZFS /boot partition and Arch installed on a nested dataset:  
  
 
{{hc|/boot/grub/grub.cfg|<nowiki>
 
{{hc|/boot/grub/grub.cfg|<nowiki>
set timeout=2
+
set timeout=5
 
set default=0
 
set default=0
  
# (0) Arch Linux
 
 
menuentry "Arch Linux" {
 
menuentry "Arch Linux" {
     set root=(hd0,1)
+
     search -u UUID
     linux /vmlinuz-linux zfs=zroot
+
     linux /vmlinuz-linux zfs=zroot/ROOT/default rw
 
     initrd /initramfs-linux.img
 
     initrd /initramfs-linux.img
 
}
 
}
</nowiki>
+
</nowiki>}}
}}
+
 
 +
==== error: failed to get canonical path of ====
 +
 
 +
[https://www.archlinux.org/packages/?repo=Core&name=grub GRUB] is built without ZFS support resulting in grub-mkconfig and grub-install failing with the following errors:
 +
 
 +
# grub-mkconfig -o /boot/grub/grub.cfg
 +
/usr/bin/grub-probe: error: failed to get canonical path of `/dev/bus-Your_Disk_ID-part#'
 +
 
 +
grub-install: error: failed to get canonical path of `/dev/bus-Your_Disk_ID-part#'
 +
 
 +
Rebuilding GRUB with ZFS support via the [[Arch Build System]] will ensure the tools properly support the filesystem and alleviate the errors. The [[Arch Build System]] provides a set of tools that can be used to create and package software for installation on Arch Linux systems. {{Pkg|subversion}} is utilised to access the package sources and must be installed before proceeding. The base and base-devel package groups must be installed prior to building packages and GRUB also requires: autogen, fuse2, help2man, python, rsync and ttf-dejavu to be present.
 +
 
 +
After satisfying all of the prerequisites, checkout and build the GRUB package from source. The ABS tools do not allow building packages as root.
 +
 
 +
$ svn checkout --depth=empty <nowiki>svn://svn.archlinux.org/packages</nowiki>
 +
$ cd packages
 +
$ svn update grub
 +
$ mkdir grub/build
 +
$ cp grub/trunk/* grub/build
 +
$ cd grub/build
 +
$ makepkg
  
===For UEFI motherboards===
+
It is also possible to workaround the issue, creating a symbolic link at the location GRUB's tools fail to resolve which points to the regular Linux device name where the affected ZFS pool is hosted masks the problem.
  
Use {{ic|EFISTUB}} and {{ic|rEFInd}} for the UEFI boot loader. See [[Beginners' Guide#For UEFI motherboards]].  The kernel parameters in {{ic|refind_linux.conf}} for ZFS should include {{ic|1=zfs=bootfs}} or {{ic|1=zfs=zroot}} so the system can boot from ZFS. The 'root' and 'rootfstype' parameters aren't needed.
+
=== For UEFI motherboards ===
  
==Unmount and restart==
+
Use {{ic|EFISTUB}} and {{ic|rEFInd}} for the UEFI boot loader. The kernel parameters in {{ic|refind_linux.conf}} for ZFS should include {{ic|1=zfs=bootfs}} or {{ic|1=zfs=zroot}} so the system can boot from ZFS. The {{ic|root}} and {{ic|rootfstype}} parameters are not needed.
  
We're almost done!
+
== Unmount and restart ==
  
{{bc|# exit
+
We are almost done!
# umount /mnt/boot
+
# exit
# zfs umount -a
+
# umount /mnt/boot (if you have a legacy boot partition)
# zpool export zroot
+
# zfs umount -a
# reboot}}
+
# zpool export zroot
 +
Now reboot.
  
 
{{Warning|If you do not properly export the zpool, the pool will refuse to import in the ramdisk environment and you will be stuck at the busybox terminal.}}
 
{{Warning|If you do not properly export the zpool, the pool will refuse to import in the ramdisk environment and you will be stuck at the busybox terminal.}}
  
==After the first boot==
+
== After the first boot ==
 +
 
 
If everything went fine up to this point, your system will boot. Once.
 
If everything went fine up to this point, your system will boot. Once.
For your system to be able to reboot without issues, you need to enable the ZFS service and set the hostid. The proper way to do this is:
+
For your system to be able to reboot without issues, you need to enable the {{ic|zfs.target}} to auto mount the pools and set the hostid.
 +
 
 +
For each pool you want automatically mounted execute:
 +
# zpool set cachefile=/etc/zfs/zpool.cache <pool>
 +
Enable the target with [[systemd]]:
 +
# systemctl enable zfs.target
 +
 
 +
When running ZFS on root, the machine's hostid will not be available at the time of mounting the root filesystem. There are two solutions to this. You can either place your spl hostid in the [[kernel parameters]] in your boot loader. For example, adding {{ic|<nowiki>spl.spl_hostid=0x00bab10c</nowiki>}}, to get your number use the {{ic|hostid}} command.
 +
 
 +
The other, and suggested, solution is to make sure that there is a hostid in {{ic|/etc/hostid}}, and then regenerate the initramfs image which will copy the hostid into the initramfs image. To write the hostid file safely you need to use a small C program:
 +
 
 +
#include <stdio.h>
 +
#include <errno.h>
 +
#include <unistd.h>
 +
 +
int main() {
 +
    int res;
 +
    res = sethostid(gethostid());
 +
    if (res != 0) {
 +
        switch (errno) {
 +
            case EACCES:
 +
            fprintf(stderr, "Error! No permission to write the"
 +
                          " file used to store the host ID.\n"
 +
                          "Are you root?\n");
 +
            break;
 +
            case EPERM:
 +
            fprintf(stderr, "Error! The calling process's effective"
 +
                            " user or group ID is not the same as"
 +
                            " its corresponding real ID.\n");
 +
            break;
 +
            default:
 +
            fprintf(stderr, "Unknown error.\n");
 +
        }
 +
        return 1;
 +
    }
 +
    return 0;
 +
}
  
{{bc|# systemctl enable zfs.service}}
+
Copy it, save it as {{ic|writehostid.c}} and compile it with {{ic|gcc -o writehostid writehostid.c}}, finally execute it and regenerate the initramfs image:
  
When running ZFS on root, the machine's hostid will not be available at the time of mounting the root filesystem. There are two solutions to this. You can either place your spl hostid in the [[kernel parameters]] in your boot loader. For example, adding <code>spl.spl_hostid=0x00bab10c</code>.
+
# ./writehostid
 +
# mkinitcpio -p linux
  
The other solution is to make sure that there is a hostid in <code>/etc/hostid</code>, and then regenerate the initramfs image. Which will copy the hostid into the initramfs image.
+
You can now delete the two files {{ic|writehostid.c}} and {{ic|writehostid}}. Your system should work and reboot properly now.
  
  # hostid > /etc/hostid
+
== Native encryption ==
  # mkinitcpio -p linux
+
{{Warning|Encryption in ZFS is not yet merged upsteam. So do this at you own risk, since it might break.}}
 +
To use native ZFS encryption, you will need a patched zfs package like {{AUR|zfs-encryption-dkms-git}} and embed it into the archiso.
 +
Then just follow the normal procedure shown before with the exception that you add the following parameters when creating the dataset:
 +
# zfs create -o encryption=on -o keyformat=passphrase -o mountpoint=none zroot/ROOT
 +
# zfs create -o encryption=on -o keyformat=passphrase -o mountpoint=none zroot/data
 +
If you want a single passphrase for both your root and home partition, encrypt only one dataset instead:
 +
# zfs create -o encryption=on -o keyformat=passphrase -o mountpoint=none zroot/encr
 +
# zfs create -o mountpoint=none zroot/encr/ROOT
 +
# zfs create -o mountpoint=none zroot/encr/data
  
 +
When importing the pool use {{ic|-l}}, to decrypt all datasets
 +
# zpool import -d /dev/disk/by-id -R /mnt -l zroot
  
That's it! Your system should work and reboot properly now.
+
On reboot, you will be asked for your passphrase.
  
==See also==
+
== See also ==
  
 
* [https://github.com/dajhorn/pkg-zfs/wiki/HOWTO-install-Ubuntu-to-a-Native-ZFS-Root-Filesystem HOWTO install Ubuntu to a Native ZFS Root]
 
* [https://github.com/dajhorn/pkg-zfs/wiki/HOWTO-install-Ubuntu-to-a-Native-ZFS-Root-Filesystem HOWTO install Ubuntu to a Native ZFS Root]
* [http://lildude.co.uk/zfs-cheatsheet ZFS Cheatsheet]
+
* [http://lildude.co.uk/zfs-cheatsheet ZFS cheatsheet]
* [http://www.funtoo.org/wiki/ZFS_Install_Guide Funtoo ZFS Install Guide]
+
* [http://www.funtoo.org/wiki/ZFS_Install_Guide Funtoo ZFS install guide]

Latest revision as of 19:07, 7 August 2017

Related articles

This article details the steps required to install Arch Linux onto a ZFS root filesystem.

Installation

See ZFS#Installation for installing the ZFS packages. If installing Arch Linux onto ZFS from the archiso, it would be easier to use the archzfs repository.

Embedding archzfs into archiso

See ZFS article.

Partition the destination drive

Review Partitioning for information on determining the partition table type to use for ZFS. ZFS supports GPT and MBR partition tables.

ZFS manages its own partitions, so only a basic partition table scheme is required. The partition that will contain the ZFS filesystem should be of the type bf00, or "Solaris Root".

Drives larger than 2TB require a GPT partition table. GRUB on BIOS/GPT configurations require a small (1~2MiB) BIOS boot partition to embed its image of boot code.

Depending upon your machine's firmware or your choice of boot mode, booting may or may not require an EFI partition. On a BIOS machine (or a UEFI machine booting in legacy mode) EFI partition is not required. Consult Boot loaders for more info.

Partition scheme

Here is an example of a basic partition scheme that could be employed for your ZFS root install on a BIOS/MBR installation using GRUB:

Part     Size   Type
----     ----   -------------------------
   1     XXXG   Solaris Root (bf00)

Using GRUB on a BIOS (or UEFI machine in legacy boot mode) machine but using a GPT partition table:

Part     Size   Type
----     ----   -------------------------
   1       2M   BIOS boot partition (ef02)
   2     XXXG   Solaris Root (bf00)

Another example, this time using a UEFI-specific bootloader (such as rEFInd) and GPT:

Part     Size   Type
----     ----   -------------------------
   1     100M   EFI boot partition (ef00)
   2     XXXG   Solaris Root (bf00)

ZFS does not support swap files. If you require a swap partition, see ZFS#Swap volume for creating a swap ZVOL.

Tip: Bootloaders with support for ZFS are described in #Install and configure the bootloader.
Warning: Several GRUB bugs (bug #42861, zfsonlinux/grub/issues/5) complicate installing it on ZFS partitions, see #Install and configure the bootloader for a workaround

Example parted commands

Here are some example commands to partition a drive for the second scenario above ie using BIOS/legacy boot mode with a GPT partition table and a (slighty more than) 1MB BIOS boot partition for GRUB:

# parted /dev/sdx
(parted)mklabel gpt
(parted)mkpart non-fs 0% 2
(parted)mkpart primary 2 100%
(parted)set 1 bios_grub on
(parted)set 2 boot on
(parted)quit

You can achieve the above in a single command like so:

parted --script /dev/sdx mklabel gpt mkpart non-fs 0% 2 mkpart primary 2 100% set 1 bios_grub on set 2 boot on

If you are creating an EFI partition then that should have the boot flag set instead of the root partition.

Format the destination disk

If you have opted for a boot partition as well as any other non-ZFS system partitions then format them. Do not do anything to the Solaris partition nor to the BIOS boot partition. ZFS will manage the first, and your bootloader the second.

Setup the ZFS filesystem

First, make sure the ZFS modules are loaded,

# modprobe zfs

Create the root zpool

# zpool create -f zroot /dev/disk/by-id/id-to-partition-partx
Warning:
  • Always use id names when working with ZFS, otherwise import errors will occur.
  • The zpool command will normally activate all features. See ZFS#GRUB-compatible pool creation when using GRUB.

Create your datasets

Instead of using conventional disk partitions, ZFS has the concept of datasets to manage your storage. Unlike disk partitions, datasets have no fixed size and allow for different attributes, such as compression, to be applied per dataset. Normal ZFS datasets are mounted automatically by ZFS whilst legacy datasets are required to be mounted using fstab or with the traditional mount command.

One of the most useful features of ZFS is boot environments. Boot environments allow you to create a bootable snapshot of your system that you can revert to at any time instantly by simply rebooting and booting from that boot environment. This can make doing system updates much safer and is also incredibly useful for developing and testing software. In order to be able to use beadm to manage boot environments your datasets must be configured properly. Key to this are that you split your data directories (such as /home) into datasets that are distinct from your system datasets and that you do not place data in the root of the pool as this cannot be moved afterwards.

You should always create a dataset for at least your root filesystem and in nearly all cases you will also want /home to be in a separate dataset. You may decide you want your logs to persist over boot environments. If you are a running any software that stores data outside of /home (such as is the case for database servers) you should structure your datasets so that the data directories of the software you want to run are separated out from the root dataset.

With these example commands, we will create a basic boot environment compatible configuration comprising of just root and /home datasets with lz4 compression to save space and improve IO performance:

# zfs create -o mountpoint=none zroot/data
# zfs create -o mountpoint=none zroot/ROOT
# zfs create -o compression=lz4 -o mountpoint=/ zroot/ROOT/default
# zfs create -o compression=lz4 -o mountpoint=/home zroot/data/home

Configure the root filesystem

If you have just created your zpool, it will be mounted in a dir at the root of your tree named after the pool (ie /zroot). If the following set commands fail, you may need to unmount any ZFS filesystems first:

# zfs umount -a

Now set the mount points of the datasets:

# zfs set mountpoint=/ zroot/ROOT/default
# zfs set mountpoint=legacy zroot/data/home
Note: /etc/fstab mounts occur before zfs mounts, so don't use zfs mountpoints on directories with subfolders configured to be mounted by /etc/fstab.

and put them in /etc/fstab

/etc/fstab
# <file system>        <dir>         <type>    <options>              <dump> <pass>
zroot/ROOT/default / zfs defaults,noatime 0 0
zroot/data/home /home zfs defaults,noatime 0 0

All legacy datasets must be listed in /etc/fstab or they will not be mounted at boot.

Set the bootfs property on the descendant root filesystem so the boot loader knows where to find the operating system.

# zpool set bootfs=zroot/ROOT/default zroot

Export the pool,

# zpool export zroot
Warning: Do not skip this, otherwise you will be required to use -f when importing your pools. This unloads the imported pool.
Note: This might fail if you added a swap partition. You need to turn it off with the swapoff command.

Finally, re-import the pool,

# zpool import -d /dev/disk/by-id -R /mnt zroot
Note: -d is not the actual device id, but the /dev/by-id directory containing the symbolic links.

If this command fails and you are asked to import your pool via its numeric ID, run zpool import to find out the ID of your pool then use a command such as: zpool import 9876543212345678910 -R /mnt zroot

If there is an error in this step, you can export the pool to redo the command. The ZFS filesystem is now ready to use.

Be sure to bring the zpool.cache file into your new system. This is required later for the ZFS daemon to start.

# cp /etc/zfs/zpool.cache /mnt/etc/zfs/zpool.cache

if you do not have /etc/zfs/zpool.cache, create it:

# zpool set cachefile=/etc/zfs/zpool.cache zroot

Install and configure Arch Linux

Follow the following steps using the Installation guide. It will be noted where special consideration must be taken for ZFSonLinux.

  • First mount any legacy or non-ZFS boot or system partitions using the mount command.
  • Install the base system.
  • The procedure described in Installation guide#Fstab is usually overkill for ZFS. ZFS usually auto mounts its own partitions, so we do not need ZFS partitions in fstab file, unless the user made legacy datasets of system directories. To generate the fstab for filesystems, use:
# genfstab -U -p /mnt >> /mnt/etc/fstab
  • Edit the /etc/fstab:
Note:
  • If you chose to create legacy datasets for system directories, keep them in this fstab!
  • Comment out all non-legacy datasets apart from the root dataset, the swap file and the boot/EFI partition. It is a convention to replace the swap's uuid with /dev/zvol/zroot/swap.
  • You need to add the Arch ZFS repository to /etc/pacman.conf, sign its key and install zfs-linux (or zfs-linux-lts if you are running the LTS kernel) within the arch-chroot before you can update the ramdisk with ZFS support.
  • When creating the initial ramdisk, first edit /etc/mkinitcpio.conf and add zfs before filesystems. Also, move keyboard hook before zfs so you can type in console if something goes wrong. You may also remove fsck (if you are not using Ext3 or Ext4). Your HOOKS line should look something like this:
HOOKS="base udev autodetect modconf block keyboard zfs filesystems"

When using systemd in the initrd, you need to install mkinitcpio-sd-zfsAUR and add the sd-zfs hook after the systemd hook instead of the zfs hook. Keep in mind that this hook uses different kernel parameters than the default zfs hook, more information can be found at the project page.

Note:
  • If you are using a separate dataset for /usr and have followed the instructions below, you must make sure you have the usr hook enabled after zfs, or your system will not boot.

Install and configure the bootloader

For BIOS motherboards

Install GRUB onto your disk as instructed here: GRUB#BIOS systems. grub-mkconfig fails to properly generate entries for systems hosted on ZFS. Users can either attempt to correct the output of grub-mkconfig or generate and edit grub.cfg manually. The GRUB manual provides detailed information on manually configuring the software which you can supplement with GRUB and GRUB/Tips and tricks.

When booting from ZFS, kernel and initrd paths have to be in the following format:

/dataset/@/actual/path  

Example with Arch installed on the root dataset:

/boot/grub/grub.cfg
set timeout=5
set default=0

menuentry "Arch Linux" {
    search -u UUID
    linux /@/boot/vmlinuz-linux zfs=zroot rw
    initrd /@/boot/initramfs-linux.img
}

Example with Arch installed on a nested dataset:

/boot/grub/grub.cfg
set timeout=5
set default=0

menuentry "Arch Linux" {
    search -u UUID
    linux /ROOT/default/@/boot/vmlinuz-linux zfs=zroot/ROOT/default rw 
    initrd /ROOT/default/@/boot/initramfs-linux.img
}

Example with a separate non-ZFS /boot partition and Arch installed on a nested dataset:

/boot/grub/grub.cfg
set timeout=5
set default=0

menuentry "Arch Linux" {
    search -u UUID
    linux /vmlinuz-linux zfs=zroot/ROOT/default rw
    initrd /initramfs-linux.img
}

error: failed to get canonical path of

GRUB is built without ZFS support resulting in grub-mkconfig and grub-install failing with the following errors:

# grub-mkconfig -o /boot/grub/grub.cfg
/usr/bin/grub-probe: error: failed to get canonical path of `/dev/bus-Your_Disk_ID-part#'
grub-install: error: failed to get canonical path of `/dev/bus-Your_Disk_ID-part#'

Rebuilding GRUB with ZFS support via the Arch Build System will ensure the tools properly support the filesystem and alleviate the errors. The Arch Build System provides a set of tools that can be used to create and package software for installation on Arch Linux systems. subversion is utilised to access the package sources and must be installed before proceeding. The base and base-devel package groups must be installed prior to building packages and GRUB also requires: autogen, fuse2, help2man, python, rsync and ttf-dejavu to be present.

After satisfying all of the prerequisites, checkout and build the GRUB package from source. The ABS tools do not allow building packages as root.

$ svn checkout --depth=empty svn://svn.archlinux.org/packages
$ cd packages
$ svn update grub
$ mkdir grub/build
$ cp grub/trunk/* grub/build
$ cd grub/build
$ makepkg

It is also possible to workaround the issue, creating a symbolic link at the location GRUB's tools fail to resolve which points to the regular Linux device name where the affected ZFS pool is hosted masks the problem.

For UEFI motherboards

Use EFISTUB and rEFInd for the UEFI boot loader. The kernel parameters in refind_linux.conf for ZFS should include zfs=bootfs or zfs=zroot so the system can boot from ZFS. The root and rootfstype parameters are not needed.

Unmount and restart

We are almost done!

# exit
# umount /mnt/boot (if you have a legacy boot partition)
# zfs umount -a
# zpool export zroot

Now reboot.

Warning: If you do not properly export the zpool, the pool will refuse to import in the ramdisk environment and you will be stuck at the busybox terminal.

After the first boot

If everything went fine up to this point, your system will boot. Once. For your system to be able to reboot without issues, you need to enable the zfs.target to auto mount the pools and set the hostid.

For each pool you want automatically mounted execute:

# zpool set cachefile=/etc/zfs/zpool.cache <pool>

Enable the target with systemd:

# systemctl enable zfs.target

When running ZFS on root, the machine's hostid will not be available at the time of mounting the root filesystem. There are two solutions to this. You can either place your spl hostid in the kernel parameters in your boot loader. For example, adding spl.spl_hostid=0x00bab10c, to get your number use the hostid command.

The other, and suggested, solution is to make sure that there is a hostid in /etc/hostid, and then regenerate the initramfs image which will copy the hostid into the initramfs image. To write the hostid file safely you need to use a small C program:

#include <stdio.h>
#include <errno.h>
#include <unistd.h>

int main() {
    int res;
    res = sethostid(gethostid());
    if (res != 0) {
        switch (errno) {
            case EACCES:
            fprintf(stderr, "Error! No permission to write the"
                         " file used to store the host ID.\n"
                         "Are you root?\n");
            break;
            case EPERM:
            fprintf(stderr, "Error! The calling process's effective"
                            " user or group ID is not the same as"
                            " its corresponding real ID.\n");
            break;
            default:
            fprintf(stderr, "Unknown error.\n");
        }
        return 1;
    }
    return 0;
}

Copy it, save it as writehostid.c and compile it with gcc -o writehostid writehostid.c, finally execute it and regenerate the initramfs image:

# ./writehostid
# mkinitcpio -p linux

You can now delete the two files writehostid.c and writehostid. Your system should work and reboot properly now.

Native encryption

Warning: Encryption in ZFS is not yet merged upsteam. So do this at you own risk, since it might break.

To use native ZFS encryption, you will need a patched zfs package like zfs-encryption-dkms-gitAUR and embed it into the archiso. Then just follow the normal procedure shown before with the exception that you add the following parameters when creating the dataset:

# zfs create -o encryption=on -o keyformat=passphrase -o mountpoint=none zroot/ROOT
# zfs create -o encryption=on -o keyformat=passphrase -o mountpoint=none zroot/data

If you want a single passphrase for both your root and home partition, encrypt only one dataset instead:

# zfs create -o encryption=on -o keyformat=passphrase -o mountpoint=none zroot/encr
# zfs create -o mountpoint=none zroot/encr/ROOT
# zfs create -o mountpoint=none zroot/encr/data

When importing the pool use -l, to decrypt all datasets

# zpool import -d /dev/disk/by-id -R /mnt -l zroot

On reboot, you will be asked for your passphrase.

See also