Difference between revisions of "Installing Arch Linux on ZFS"

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(I added a GPT partition example including a BIOS boot partition and the steps to make your system rebootable after installation. I did it because I tried to follow the existing wiki to install ZFS on my system, and it didn't work well.)
(State the importance of enabling ACL support for /var/log/journalctl, otherwise Arch dies a little :()
 
(138 intermediate revisions by 32 users not shown)
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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}}
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{{Related|ZFS}}
{{Article summary wiki|ZFS}}
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{{Related|Experimenting with ZFS}}
{{Article summary wiki|ZFS on FUSE}}
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{{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:
 +
 
 +
{{bc|<nowiki>
 +
Part    Size  Type
 +
----    ----  -------------------------
 +
  1      2M  BIOS boot partition (ef02)
 +
  2    XXXG  Solaris Root (bf00)</nowiki>
 +
}}
 +
 
 +
Another example, this time using a UEFI-specific bootloader (such as [[rEFInd]]) and GPT:
  
{{hc|# nano /etc/pacman.conf|<nowiki>
+
{{bc|<nowiki>
[demz-repo-core]
+
Part    Size  Type
Server = http://demizerone.com/$repo/$arch</nowiki>
+
----    ----  -------------------------
 +
  1    100M  EFI boot partition (ef00)
 +
  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)}}
+
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 ([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}}
 +
 
 +
=== 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 ==
  
Next, add the archzfs maintainer's PGP key to the local trust:
+
First, make sure the ZFS modules are loaded,
  
{{bc|# pacman-key -r 0EE7A126
+
# modprobe zfs
# pacman-key --lsign-key 0EE7A126}}
 
  
Finally, update the pacman databases and install archzfs:
+
=== Create the root zpool ===
  
{{bc|# pacman -Syy}}
+
# zpool create -f zroot /dev/disk/by-id/''id-to-partition-partx''
  
This is also the best time to install your favorite text editor, otherwise nano or vi will have to be used.
+
{{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]].}}
  
{{bc|# pacman -S archzfs dosfstools gptfdisk vim}}
+
=== Create your datasets ===
  
==Partition the destination drive==
+
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.
  
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.
+
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.  
  
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".
+
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.
  
===Partition scheme===
+
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:
  
Here is an example, using MBR, of a basic partition scheme that could be employed for your ZFS root setup:
+
# 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
  
{{bc|<nowiki>Part    Size  Type
+
{{Note|You will need to enable ACL support on the pool that will house {{ic|/var/log/journal}}, i.e. {{ic|1=zfs set acltype=posixacl ...}}. See [[Systemd#systemd-tmpfiles-setup.service fails to start at boot]] for more information.}}
----    ----  -------------------------
 
  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.
+
=== Configure the root filesystem ===
  
{{bc|<nowiki>Part    Size  Type
+
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:
----    ----  -------------------------
 
  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.
+
# zfs umount -a
  
{{tip|Bootloaders with support for ZFS are described in [[#Install and configure the bootloader]].}}
+
Now set the mount points of the datasets:
  
==Format the destination disk==
+
# zfs set mountpoint=/ zroot/ROOT/default
 +
# zfs set mountpoint=legacy zroot/data/home
  
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.
+
{{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}}.}}
  
==Setup the ZFS filesystem==
+
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}}
  
First, make sure the ZFS modules are loaded,
+
All legacy datasets must be listed in {{ic|/etc/fstab}} or they will not be mounted at boot.
  
{{bc|# modprobe zfs}}
+
Set the bootfs property on the descendant root filesystem so the boot loader knows where to find the operating system.
  
===Create the root zpool===
+
# zpool set bootfs=zroot/ROOT/default zroot
  
{{bc|# zpool create zroot /dev/disk/by-id/<id-to-partition>}}
+
Export the pool,
  
{{Warning|Always use id names when working with ZFS, otherwise import errors will occur.}}
+
# zpool export zroot
  
===Create necessary filesystems===
+
{{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.}}
  
If so desired, sub-filesystem mount points such as /home and /root can be created with the following commands:
+
Finally, re-import the pool,
  
{{bc|# zfs create zroot/home
+
# zpool import -d /dev/disk/by-id -R /mnt zroot
# 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.
+
{{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}}
 +
}}
  
<!-- Taken the following Swap info from https://wiki.archlinux.org/index.php/ZFS -->
+
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.
  
=== Swap partition ===
+
Be sure to bring the {{ic|zpool.cache}} file into your new system. This is required later for the ZFS daemon to start.
  
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.
+
# cp /etc/zfs/zpool.cache /mnt/etc/zfs/zpool.cache
  
Create a 8gb (or whatever is required) ZFS volume:
+
if you do not have {{ic|/etc/zfs/zpool.cache}}, create it:
  
{{bc|# zfs create -V 8G -b 4K <pool>/swap}}
+
# zpool set cachefile=/etc/zfs/zpool.cache zroot
  
Initialize and enable the volume as a swap partition:
+
== Install and configure Arch Linux ==
  
{{bc|# mkswap /dev/zvol/<pool>/swap
+
Follow the following steps using the [[Installation guide]]. It will be noted where special consideration must be taken for ZFSonLinux.
# 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:
+
* First mount any legacy or non-ZFS boot or system partitions using the mount command.
  
{{bc|/dev/zvol/<pool>/swap none swap defaults 0 0}}
+
* Install the base system.
  
Make sure to unmount all ZFS filesystems before rebooting the machine, otherwise any ZFS pools will refuse to be imported:
+
* 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|# zfs umount -a}}
+
# genfstab -U -p /mnt >> /mnt/etc/fstab
  
===Configure the root filesystem===
+
* Edit the {{ic|/etc/fstab}}:
  
First, set the mount point of the root filesystem:
+
{{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|<nowiki># zfs set mountpoint=/ zroot</nowiki>}}
+
* 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.
  
and optionally, any sub-filesystems:
+
* 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"
  
{{bc|<nowiki># zfs set mountpoint=/home zroot/home
+
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].
# 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.
+
{{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.
 +
}}
  
{{bc|<nowiki># zpool set bootfs=zroot zroot</nowiki>}}
+
* [[Regenerate the initramfs]].
  
Export the pool,
+
== Install and configure the bootloader ==
  
{{bc|# zpool export zroot}}
+
=== Using GRUB with BIOS and EFI motherboards ===
  
{{Warning|Don't skip this, otherwise you will be required to use -f when importing your pools. This unloads the imported pool.}}
+
Install GRUB onto your disk as instructed here: [[GRUB#BIOS systems]] or [[GRUB#UEFI systems]]. 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]].
{{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,
+
==== error: failed to get canonical path of ====
  
{{bc|# zpool import -d /dev/disk/by-id -R /mnt zroot}}
+
{{ic|grub-mkconfig}} fails to properly generate entries for systems hosted on ZFS.
  
{{Note|"-d" is not the actual device id, but the /dev/by-id directory containing the symlinks.}}
+
# grub-mkconfig -o /boot/grub/grub.cfg
 +
/usr/bin/grub-probe: error: failed to get canonical path of `/dev/bus-Your_Disk_ID-part#'
  
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.
+
grub-install: error: failed to get canonical path of `/dev/bus-Your_Disk_ID-part#'
  
==Install and configure Arch Linux==
+
To work around this you must set this environment variable: {{ic|1=ZPOOL_VDEV_NAME_PATH=1}}. For example:
  
Follow the following steps using the [[Beginners' Guide]]. It will be noted where special consideration must be taken for ZFSonLinux.
+
# ZPOOL_VDEV_NAME_PATH=1 grub-mkconfig -o /boot/grub/grub.cfg
  
* First mount any boot or system partitions using the mount command.
 
  
* Install the base system.
+
==== Booting your kernel and initrd from ZFS ====
  
* 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>}}
+
You may skip this section if you have your kernel and initrd on a separate {{ic|/boot}} partition using something like ext4 or vfat.
  
*Edit the /etc/fstab:
+
Otherwise grub needs to load your kernel and initrd are from a ZFS dataset the 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>}}
}}
 
  
===For UEFI motherboards===
+
=== Using rEFInd with UEFI motherboards ===
  
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.
+
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.
  
==Unmount and restart==
+
== Unmount and restart ==
  
We're almost done!
+
We are almost done!
 +
# exit
 +
# umount /mnt/boot (if you have a legacy boot partition)
 +
# zfs umount -a
 +
# zpool export zroot
 +
Now reboot.
  
{{bc|# exit
+
{{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.}}
# umount /mnt/boot
 
# zfs umount -a
 
# zpool export zroot
 
# 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 ==
  
==Proper zpool exporting on shutdown==
 
 
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 properly export the ZFS pool on shutdown. 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.
  
{{bc|# systemctl enable zfs.service}}
+
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
  
The systemd service file installed with archzfs by default does not work properly because it ends up with the system trying to import your zpool and mount the filesystem twice. Here's how it should be.
+
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.
  
{{hc|/usr/lib/systemd/system/zfs.service|<nowiki>
+
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:
[Unit]
 
Description=Zettabyte File System (ZFS)
 
Documentation=man:zfs(8) man:zpool(8)
 
DefaultDependencies=no
 
After=cryptsetup.target
 
Before=local-fs.target
 
Conflicts=shutdown.target umount.target
 
  
[Service]
+
#include <stdio.h>
Type=oneshot
+
#include <errno.h>
RemainAfterExit=yes
+
#include <unistd.h>
ExecStart=/sbin/modprobe zfs
+
 +
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;
 +
}
  
#remove or comment out this three lines
+
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:
#ExecStart=/usr/bin/zpool import -c /etc/zfs/zpool.cache -aN
 
#ExecStart=/usr/bin/zfs mount -a
 
#ExecStart=/usr/bin/zfs share -a
 
  
ExecStop=/usr/bin/zfs umount -a
+
# ./writehostid
 +
# mkinitcpio -p linux
  
#add this line
+
You can now delete the two files {{ic|writehostid.c}} and {{ic|writehostid}}. Your system should work and reboot properly now.
ExecStop=/usr/bin/zpool export zroot
 
  
[Install]
+
== Native encryption ==
WantedBy=local-fs.target
+
{{Warning|Encryption does not exist in a stable release, yet. So do this at you own risk, since it might break.}}
</nowiki>
+
To use native ZFS encryption, you will need a recent enough zfs package like {{AUR|zfs-linux-git}} 0.7.0.r26 or newer 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 17:39, 9 October 2017

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
Note: You will need to enable ACL support on the pool that will house /var/log/journal, i.e. zfs set acltype=posixacl .... See Systemd#systemd-tmpfiles-setup.service fails to start at boot for more information.

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

Using GRUB with BIOS and EFI motherboards

Install GRUB onto your disk as instructed here: GRUB#BIOS systems or GRUB#UEFI systems. The GRUB manual provides detailed information on manually configuring the software which you can supplement with GRUB and GRUB/Tips and tricks.

error: failed to get canonical path of

grub-mkconfig fails to properly generate entries for systems hosted on ZFS.

# 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#'

To work around this you must set this environment variable: ZPOOL_VDEV_NAME_PATH=1. For example:

# ZPOOL_VDEV_NAME_PATH=1 grub-mkconfig -o /boot/grub/grub.cfg


Booting your kernel and initrd from ZFS

You may skip this section if you have your kernel and initrd on a separate /boot partition using something like ext4 or vfat.

Otherwise grub needs to load your kernel and initrd are from a ZFS dataset the 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
}

Using rEFInd with 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 does not exist in a stable release, yet. So do this at you own risk, since it might break.

To use native ZFS encryption, you will need a recent enough zfs package like zfs-linux-gitAUR 0.7.0.r26 or newer 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