Difference between revisions of "Installing Arch Linux on ZFS"

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{{Article summary end}}
 
{{Article summary end}}
  
{{Merge|ZFS|This article has too much duplicate installation information from the Beginners Guide.}}
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This article details the steps required to install Arch Linux onto a root ZFS filesystem. This article supplements the [[Beginners' Guide]].
  
The [[Wikipedia:ZFS|Zettabyte File System (ZFS)]] is an advanced [[Wikipedia:Copy-on-write|copy-on-write]] filesystem designed to preserve data integrity from a multitude of possible corruption scenarios as well as provide simple administration features. ZFS makes disk administration effortless with support ZFS storage pools (zpools) and automatic mount handling. First released in 2005 for Solaris OS, ZFS has since become the flag bearer for next generation filesystems.
+
== Installing archzfs ==
  
ZFS was first developed and released by Sun (now owned by Oracle) as [[Wikipedia:Open source software|Open Source Software]] licensed under the [[Wikipedia:Common Development and Distribution License|Common Development and Distribution License]] (CDDL) which is famously [http://arstechnica.com/information-technology/2010/06/uptake-of-native-linux-zfs-port-hampered-by-license-conflict/ incompatible with the GNU Public License]. This incompatibility prevents ZFS from being merged into the mainline kernel, and generally presents some obstacles for users that want to use ZFS in Linux.
+
Using the archzfs repository is highly recommended for effortless updates.
  
[http://zfsonlinux.org/ ZFSonLinux.org] is a project funded by the [https://www.llnl.gov/ Lawrence Livermore National Laboratory] to develop a native Linux kernel module for its massive storage requirements and super computers.
+
{{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.}}
  
==Notes before installation==
+
{{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].}}
  
* 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].
+
=== Embedding archzfs into archiso ===
  
* 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.
  
==Boot from the installation media==
+
=== Using the archzfs repository ===
  
It is a good idea make an installation media with the needed software included. Otherwise, you will need the latest archiso installation media burned to a CD or a USB key.  
+
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:
  
To embed {{ic|zfs}} in the archiso, from an existing install, download the {{ic|archiso}} package.
+
  [demz-repo-core]
  # pacman -S archiso
+
Server = http://demizerone.com/$repo/$arch
  
Start the process:
+
{{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 (did not build your own, above).}}
# cp -r /usr/share/archiso/configs/releng /root/media
+
 
+
Edit the {{ic|packages.x86_64}} file adding those lines:
+
spl-utils
+
spl
+
zfs-utils
+
zfs
+
 
+
Edit the {{ic|pacman.conf}} file adding those lines (TODO, correctly embed keys in the installation media?):
+
[demz-repo-archiso]
+
SigLevel = Never
+
Server = <nowiki>http://demizerone.com/$repo/$arch</nowiki>
+
 
+
Add other packages in {{ic|packages.both}}, {{ic|packages.i686}}, or {{ic|packages.x86_64}} if needed and create the image.
+
# ./build.sh -v
+
 
+
The image will be in the {{ic|/root/media/out}} directory.
+
 
+
More informations about the process can be read in [http://kroweer.wordpress.com/2011/09/07/creating-a-custom-arch-linux-live-usb/ this guide] or in the [[Archiso]] article.
+
 
+
If you are installing onto a UEFI system, see [[Unified Extensible Firmware Interface#Create UEFI bootable USB from ISO]] for creating UEFI compatible installation media.
+
 
+
==Setup pacman==
+
 
+
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:
+
 
+
{{hc|# nano /etc/pacman.conf|<nowiki>
+
[demz-repo-core]
+
Server = http://demizerone.com/$repo/$arch</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)}}
+
  
 
Next, add the archzfs maintainer's PGP key to the local trust:
 
Next, add the archzfs maintainer's PGP key to the local trust:
  
    # pacman-key -r 0EE7A126
+
# pacman-key -r 0EE7A126
    # pacman-key --lsign-key 0EE7A126
+
# pacman-key --lsign-key 0EE7A126
  
Finally, update the pacman databases,
+
Finally, update the pacman databases and install ''archzfs'':
  
    # pacman -Syy
+
# pacman -Syy archzfs
  
==Install needed packages==
+
{{Tip|This is also the best time to install your favorite text editor (otherwise {{Pkg|nano}} or {{Pkg|vi}} will have to be used) and the proper partition tools: for [[UEFI]] and [[GPT]] install {{Pkg|dosfstools}} and {{Pkg|gptfdisk}}.}}
  
This is also the best time to install your favorite text editor, otherwise nano will have to be used.
+
== Partition the destination drive ==
  
    # pacman -S archzfs dosfstools gptfdisk vim
+
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.
  
==Partition the destination drive==
+
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".
  
===UEFI systems===
+
=== Partition scheme ===
  
Use the cgdisk partition utility and create a GPT partition table:
+
Here is an example, using MBR, of a basic partition scheme that could be employed for your ZFS root setup:
  
  Part    Size  Type
+
{{bc|<nowiki>
  ====     =====  =============
+
Part    Size  Type
      1    512M  EFI (ef00)
+
----     ----  -------------------------
      2    512M  Ext4 (8300)
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  1    512M  Ext boot partition (8300)
      2    XXXG  Solaris Root (bf00)
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  2    XXXG  Solaris Root (bf00)</nowiki>
 +
}}
  
{{Note|The EFI partion will be formatted to FAT32 and contain the UEFI boot loader. The Ext4 partition will contain the boot partition and kernel images.}}
+
Here is an example using GPT. The BIOS boot partition contains the bootloader.
  
{{Note|The filesystem type codes for cgdisk are indicated in the parenthesis after the filesystem name.}}
+
{{bc|<nowiki>
 
+
Part    Size  Type
{{Warning|The EFI partition must be at least 512MB specified by the UEFI standard.}}
+
----     ----  -------------------------
 
+
  1       2M  BIOS boot partition (ef02)
===BIOS systems===
+
  1    512M  Ext boot partition (8300)
 
+
  2     XXXG  Solaris Root (bf00)</nowiki>
  Part    Size  Type
+
}}
  ====     =====  =============
+
       2    1007K  BIOS Boot Partition (ef02)
+
      1    512M  Ext4 (8300)
+
      3     XXXG  Solaris Root (bf00)
+
 
+
{{Note|You will have to create the ext4 partition first due to cgdisk's disk alignment policies. Start it at sector 2048 to leave room for the BIOS parition.}}
+
 
+
==Format the destination disk==
+
 
+
===UEFI systems===
+
 
+
Format the EFI partition to FAT32
+
 
+
    mkfs.vfat -F 32 /dev/sda1 -n EFIBOOT
+
 
+
Format the Ext4 boot partition
+
 
+
    mkfs.ext4 /dev/sda2 -L BOOT
+
  
===BIOS systems===
+
An additional partition may be required depending on your hardware and chosen bootloader. Consult [[Beginners'_Guide#Install_and_configure_a_bootloader]] for more info.
  
Format the Ext4 boot partition
+
{{Tip|Bootloaders with support for ZFS are described in [[#Install and configure the bootloader]].}}
   
+
    mkfs.ext4 /dev/sda1 -L BOOT
+
  
{{Note|The boot filesystem is {{ic|sda1}} because of the order we created the partitions}}
+
== Format the destination disk ==
  
The BIOS partition does not need a filesystem.
+
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.
  
==Setup the ZFS filesystem==
+
== Setup the ZFS filesystem ==
  
 
First, make sure the ZFS modules are loaded,
 
First, make sure the ZFS modules are loaded,
  
    # modprobe zfs
+
# modprobe zfs
  
===Create the root zpool===
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=== Create the root zpool ===
  
    # zpool create zroot /dev/disk/by-id/<id-to-partition>
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# zpool create zroot /dev/disk/by-id/''id-to-partition''
  
 
{{Warning|Always use id names when working with ZFS, otherwise import errors will occur.}}
 
{{Warning|Always use id names when working with ZFS, otherwise import errors will occur.}}
  
===Create necessary filesystems===
+
=== Create necessary filesystems ===
  
If so desired, sub-filesystem mount points such as /home and /root can be created with the following commands:
+
If so desired, sub-filesystem mount points such as {{ic|/home}} and {{ic|/root}} can be created with the following commands:
  
    # zfs create zroot/home
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# zfs create zroot/home
    # zfs create zroot/root
+
# zfs create zroot/root
<!-- Taken the following Swap info from https://wiki.archlinux.org/index.php/ZFS -->
+
=== Swap partition ===
+
  
ZFS does not allow to use swapfiles, but you can use a ZFS volume as swap partition. It is importart to set the ZVOL block size to match the system page size, for x86_64 systems that is 4k.
+
Note that if you want to use other datasets for system directories ({{ic|/var}} or {{ic|/etc}} included) your system will not boot unless they are listed in {{ic|/etc/fstab}}!  We will address that at the appropriate time in this tutorial.
  
Create a 8gb zfs volume:
+
=== Swap partition ===
  
  # zfs create -V 8G -b 4K <pool>/swap
+
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.
  
Prepare it as swap partition:
+
Create a 8 GB (or whatever is required) ZFS volume:
  
  # mkswap /dev/zvol/<pool>/swap
+
# zfs create -V 8G -b 4K ''pool''/swap
  
Enable swap:
+
Initialize and enable the volume as a swap partition:
  
  # swapon /dev/zvol/<pool>/swap
+
# mkswap /dev/zvol/''pool''/swap
 +
# swapon /dev/zvol/''pool''/swap
  
To make it permament you need to edit your {{ic|/mnt/etc/fstab}} after pacstraping the system:
+
After using {{ic|pacstrap}} to install the base system, edit {{ic|/''root''/etc/fstab}} to ensure the swap partition is mounted at boot:
  
Add a line to {{ic|/mnt/etc/fstab}}:
+
/dev/zvol/''pool''/swap none swap defaults 0 0
  
  /dev/zvol/<pool>/swap none swap defaults 0 0
+
Make sure to unmount all ZFS filesystems before rebooting the machine, otherwise any ZFS pools will refuse to be imported:
  
For safety, unmount all zfs filesystems if they are mounted:
+
# zfs umount -a
  
    # zfs umount -a
+
=== Configure the root filesystem ===
  
===Configure the root filesystem===
+
First, set the mount point of the root filesystem:
  
Now it is time to set the mount point of the root filesystem:
+
# zfs set mountpoint=/ zroot
 
+
    # zfs set mountpoint=/ zroot
+
  
 
and optionally, any sub-filesystems:
 
and optionally, any sub-filesystems:
  
    # zfs set mountpoint=/home zroot/home
+
# zfs set mountpoint=/home zroot/home
    # zfs set mountpoint=/root zroot/root
+
# zfs set mountpoint=/root zroot/root
  
 
Set the bootfs property on the descendant root filesystem so the boot loader knows where to find the operating system.
 
Set the bootfs property on the descendant root filesystem so the boot loader knows where to find the operating system.
  
    # zpool set bootfs=zroot zroot
+
# zpool set bootfs=zroot zroot
  
 
Export the pool,
 
Export the pool,
  
    # zpool export zroot
+
# zpool export zroot
  
{{Warning|Don't skip this, otherwise you will be required to use -f when importing your pools. This unloads the imported pool.}}
+
{{Warning|Don't 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 above. Need to turn it off with the ''swapoff'' command.}}
 
{{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,
 
Finally, re-import the pool,
  
    # zpool import -d /dev/disk/by-id -R /mnt zroot
+
# 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 symlinks.}}
+
{{Note|{{ic|-d}} is not the actual device id, but the {{ic|/dev/by-id}} directory containing the symbolic links.}}
  
 
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.
 
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.
  
==Mount the boot partitions==
+
Be sure to bring the zpool.cache file into your new system. This is required later for the ZFS daemon to start.
  
===UEFI systems===
+
# cp /etc/zfs/zpool.cache /mnt/etc/zfs/zpool.cache
  
    # mkdir /mnt/boot
+
== Install and configure Arch Linux ==
    # mount /dev/sda2 /mnt/boot
+
    # mkdir /mnt/boot/efi
+
    # mount /dev/sda1 /mnt/boot/efi
+
  
===BIOS systems===
+
Follow the following steps using the [[Beginners' Guide]]. It will be noted where special consideration must be taken for ZFSonLinux.
  
    # mkdir /mnt/boot
+
* First mount any boot or system partitions using the mount command.
    # mount /dev/sda1 /mnt/boot
+
  
==Install and configure the Arch Linux installation==
+
* Install the base system.
  
Install the base packages
+
* 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 {{ic|fstab}} file, unless the user made datasets of system directories. To generate the {{ic|fstab}} for filesystems, use:
 
+
# genfstab -U -p /mnt | grep boot >> /mnt/etc/fstab
    # pacstrap -i /mnt base base-devel
+
  
    The other packages will be installed in the chrooted environment
+
* Edit the {{ic|/etc/fstab}}:
Generate the fstab,
+
  
    # genfstab -U -p /mnt | grep boot >> /mnt/etc/fstab
+
{{Note|
 
+
* If you chose to create datasets for system directories, keep them in this {{ic|fstab}}! Comment out the lines for the '{{ic|/}}, {{ic|/root}}, and {{ic|/home}} mountpoints, rather than deleting them. You may need those UUIDs later if something goes wrong.
{{Note|ZFS auto mounts its own partitions, so we do not need ZFS partitions in fstab file.}}
+
* 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 {{ic|/dev/zvol/zroot/swap}}.
 
+
If installing on a UEFI system, you will need to load the efivars kernel module before chrooting into the installation:
+
 
+
    # modprobe efivars
+
 
+
Chroot into the installation
+
 
+
    # arch-chroot /mnt /bin/bash
+
 
+
Next, follow the [[Beginners' Guide]] from the "Locale" section to the "Configure Pacman Section". Once done, edit {{ic|pacman.conf}}, add the archzfs repo (change it to {{ic|[demz-repo-core]}} now if you were using {{ic|[demz-repo-archiso]}} earlier), and update the pacman database,
+
 
+
    # pacman -Syy
+
    # pacman -Su --ignore filesystem,bash
+
    # pacman -S bash
+
    # pacman -Su
+
   
+
    Now lets install the other needed packages.
+
    # pacman -S gnupg vim archzfs
+
 
+
Re-create the initramfs, 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. Your HOOKS line should look something like this:{{hc|/etc/mkinitcpio.conf|<nowiki>
+
HOOKS="base udev autodetect modconf block keyboard zfs filesystems"
+
</nowiki>
+
 
}}
 
}}
Regenerate the initramfs with the command:
 
 
    # mkinitcpio -p linux
 
 
Finally, set root password and add a regular user.
 
  
==Setup the bootloader==
+
* 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"
  
===UEFI systems===
+
* Regenerate the initramfs with the command:
 +
# mkinitcpio -p linux
  
Use EFISTUB and rEFInd for the UEFI boot loader. See [[Beginners' Guide#For UEFI motherboards]].  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 aren't needed.
+
== Install and configure the bootloader ==
  
===BIOS systems===
+
=== For BIOS motherboards ===
  
Follow the [[Grub2#BIOS_systems_2]] wiki. {{ic|grub-mkconfig}} fails for me, so I edited {{ic|grub.cfg}} manually.
+
Follow [[GRUB#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:
  
 
{{hc|/boot/grub/grub.cfg|<nowiki>
 
{{hc|/boot/grub/grub.cfg|<nowiki>
Line 277: Line 192:
 
     initrd /initramfs-linux.img
 
     initrd /initramfs-linux.img
 
}
 
}
</nowiki>
+
</nowiki>}}
}}
+
  
==Unmount and restart==
+
=== For UEFI motherboards ===
  
This is it, we are done!
+
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 {{ic|root}} and {{ic|rootfstype}} parameters are not needed.
  
    # exit
+
== Unmount and restart ==
    # umount /mnt/boot
+
 
    # zfs umount -a
+
We're almost done!
    # zpool export zroot
+
# exit
    # reboot
+
# umount /mnt/boot
 +
# 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.}}
 
{{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.}}
  
==Troubleshooting==
+
== After the first boot ==
 
+
If the new installation does not boot because the zpool cannot be imported, you will need to chroot into the installation and properly export the zpool. See [[ZFS#Emergency chroot repair with archzfs]].
+
 
+
Once inside the chroot environment, load the ZFS module and force import the zpool,
+
 
+
    # zpool import -a -f
+
 
+
now export the pool:
+
 
+
    # zpool export <pool>
+
  
To see your available pools, use,
+
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 {{ic|zfs}} service and set the hostid.
  
    # zpool status
+
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>}}.
  
It is necessary to export a pool because of the way ZFS uses the hostid to track the system the zpool was created on. The hostid is generated partly based on your network setup. During the installation in the archiso your network configuration could be different generating a different hostid than the one contained in your new installation. Once the zfs filesystem is exported and then re-imported in the new installation, the hostid is reset. See [http://osdir.com/ml/zfs-discuss/2011-06/msg00227.html Re: Howto zpool import/export automatically? - msg#00227].
+
The other 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.
  
If ZFS complains about "pool may be in use" after every reboot, you should properly export pool as described above, and then rebuild ramdisk in normally booted system:
+
# hostid > /etc/hostid
 +
# mkinitcpio -p linux
  
    # mkinitcpio -p linux
+
Your system should work and reboot properly now.
  
==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]

Revision as of 03:08, 29 October 2013

Template:Article summary start Template:Article summary text Template:Article summary heading Template:Article summary wiki Template:Article summary wiki Template:Article summary end

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

Installing archzfs

Using the archzfs repository is highly recommended for effortless updates.

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.
Note: 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: 0EE7A126.

Embedding archzfs into archiso

See ZFS article.

Using the archzfs repository

Activate the required network connection and then edit /etc/pacman.d/mirrorlist and configure the mirrors for pacman to use. Once that is done, edit /etc/pacman.conf and add the archzfs repository:

[demz-repo-core]
Server = http://demizerone.com/$repo/$arch
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 (did not build your own, above).

Next, add the archzfs maintainer's PGP key to the local trust:

# pacman-key -r 0EE7A126
# pacman-key --lsign-key 0EE7A126

Finally, update the pacman databases and install archzfs:

# pacman -Syy archzfs
Tip: This is also the best time to install your favorite text editor (otherwise nano or vi will have to be used) and the proper partition tools: for UEFI and GPT install dosfstools and gptfdisk.

Partition the destination drive

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.

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".

Partition scheme

Here is an example, using MBR, of a basic partition scheme that could be employed for your ZFS root setup:

Part     Size   Type
----     ----   -------------------------
   1     512M   Ext boot partition (8300)
   2     XXXG   Solaris Root (bf00)

Here is an example using GPT. The BIOS boot partition contains the bootloader.

Part     Size   Type
----     ----   -------------------------
   1       2M   BIOS boot partition (ef02)
   1     512M   Ext boot partition (8300)
   2     XXXG   Solaris Root (bf00)

An additional partition may be required depending on your hardware and chosen bootloader. Consult Beginners'_Guide#Install_and_configure_a_bootloader for more info.

Tip: Bootloaders with support for ZFS are described in #Install and configure the bootloader.

Format the destination disk

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.

Setup the ZFS filesystem

First, make sure the ZFS modules are loaded,

# modprobe zfs

Create the root zpool

# zpool create zroot /dev/disk/by-id/id-to-partition
Warning: Always use id names when working with ZFS, otherwise import errors will occur.

Create necessary filesystems

If so desired, sub-filesystem mount points such as /home and /root can be created with the following commands:

# zfs create zroot/home
# 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.

Swap partition

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.

Create a 8 GB (or whatever is required) ZFS volume:

# zfs create -V 8G -b 4K pool/swap

Initialize and enable the volume as a swap partition:

# mkswap /dev/zvol/pool/swap
# swapon /dev/zvol/pool/swap

After using pacstrap to install the base system, edit /root/etc/fstab to ensure the swap partition is mounted at boot:

/dev/zvol/pool/swap none swap defaults 0 0

Make sure to unmount all ZFS filesystems before rebooting the machine, otherwise any ZFS pools will refuse to be imported:

# zfs umount -a

Configure the root filesystem

First, set the mount point of the root filesystem:

# zfs set mountpoint=/ zroot

and optionally, any sub-filesystems:

# zfs set mountpoint=/home zroot/home
# zfs set mountpoint=/root zroot/root

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

# zpool set bootfs=zroot zroot

Export the pool,

# zpool export zroot
Warning: Don't 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 above. 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 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

Install and configure Arch Linux

Follow the following steps using the Beginners' Guide. It will be noted where special consideration must be taken for ZFSonLinux.

  • First mount any boot or system partitions using the mount command.
  • Install the base system.
  • 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:
# genfstab -U -p /mnt | grep boot >> /mnt/etc/fstab
  • Edit the /etc/fstab:
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.
  • 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.
  • 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"
  • Regenerate the initramfs with the command:
# mkinitcpio -p linux

Install and configure the bootloader

For BIOS motherboards

Follow GRUB#BIOS_systems_2 to install GRUB onto your disk. grub-mkconfig does not properly detect the ZFS filesystem, so it is necessary to edit grub.cfg manually:

/boot/grub/grub.cfg
set timeout=2
set default=0

# (0) Arch Linux
menuentry "Arch Linux" {
    set root=(hd0,1)
    linux /vmlinuz-linux zfs=zroot
    initrd /initramfs-linux.img
}

For UEFI motherboards

Use EFISTUB and rEFInd for the UEFI boot loader. See Beginners' Guide#For UEFI motherboards. 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're almost done!

# exit
# umount /mnt/boot
# 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 service and set the hostid.

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.

The other 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.

# hostid > /etc/hostid
# mkinitcpio -p linux

Your system should work and reboot properly now.

See also