Arch Linux Root on ZFS


This tutorial is based on the GRUB bootloader. Due to its independent implementation of a read-only ZFS driver, GRUB only supports a subset of ZFS features on the boot pool. [In general, bootloader treat disks as read-only to minimize the risk of damaging on-disk data.]

ZFSBootMenu is an alternative bootloader free of such limitations and has support for boot environments. Do not follow instructions on this page if you plan to use ZBM, as the layouts are not compatible. Refer to their site for installation details.


Unless stated otherwise, it is not recommended to customize system configuration before reboot.

Only use well-tested pool features

You should only use well-tested pool features. Avoid using new features if data integrity is paramount. See, for example, this comment.


  1. Disable Secure Boot. ZFS modules can not be loaded if Secure Boot is enabled.

  2. Because the kernel of latest Live CD might be incompatible with ZFS, we will use Alpine Linux Extended, which ships with ZFS by default.

    Download latest extended variant of Alpine Linux live image, verify checksum and boot from it.

    gpg --auto-key-retrieve --keyserver hkps:// --verify alpine-extended-*.asc
    dd if=input-file of=output-file bs=1M
  3. Login as root user. There is no password.

  4. Configure Internet

    setup-interfaces -r
    # You must use "-r" option to start networking services properly
    # example:
    network interface: wlan0
    WiFi name:         <ssid>
    ip address:        dhcp
    <enter done to finish network config>
    manual netconfig:  n
  5. If you are using wireless network and it is not shown, see Alpine Linux wiki for further details. wpa_supplicant can be installed with apk add wpa_supplicant without internet connection.

  6. Configure SSH server

    # example:
    ssh server:        openssh
    allow root:        "prohibit-password" or "yes"
    ssh key:           "none" or "<public key>"
  7. Set root password or /root/.ssh/authorized_keys.

  8. Connect from another computer

    ssh root@
  9. Configure NTP client for time synchronization

    setup-ntp busybox
  10. Set up apk-repo. A list of available mirrors is shown. Press space bar to continue

  11. Throughout this guide, we use predictable disk names generated by udev

    apk update
    apk add eudev
    setup-devd udev
  12. Target disk

    List available disks with

    find /dev/disk/by-id/

    If virtio is used as disk bus, power off the VM and set serial numbers for disk. For QEMU, use -drive format=raw,file=disk2.img,serial=AaBb. For libvirt, edit domain XML. See this page for examples.

    Declare disk array

    DISK='/dev/disk/by-id/ata-FOO /dev/disk/by-id/nvme-BAR'

    For single disk installation, use

  13. Set a mount point

    MNT=$(mktemp -d)
  14. Set partition size:

    Set swap size in GB, set to 1 if you don’t want swap to take up too much space


    Set how much space should be left at the end of the disk, minimum 1GB

  15. Install ZFS support from live media:

    apk add zfs
  16. Install partition tool

    apk add parted e2fsprogs cryptsetup util-linux

System Installation

  1. Partition the disks.

    Note: you must clear all existing partition tables and data structures from target disks.

    For flash-based storage, this can be done by the blkdiscard command below:

    partition_disk () {
     local disk="${1}"
     blkdiscard -f "${disk}" || true
     parted --script --align=optimal  "${disk}" -- \
     mklabel gpt \
     mkpart EFI 2MiB 1GiB \
     mkpart bpool 1GiB 5GiB \
     mkpart rpool 5GiB -$((SWAPSIZE + RESERVE))GiB \
     mkpart swap  -$((SWAPSIZE + RESERVE))GiB -"${RESERVE}"GiB \
     mkpart BIOS 1MiB 2MiB \
     set 1 esp on \
     set 5 bios_grub on \
     set 5 legacy_boot on
     partprobe "${disk}"
    for i in ${DISK}; do
       partition_disk "${i}"
  2. Setup encrypted swap. This is useful if the available memory is small:

    for i in ${DISK}; do
       cryptsetup open --type plain --key-file /dev/random "${i}"-part4 "${i##*/}"-part4
       mkswap /dev/mapper/"${i##*/}"-part4
       swapon /dev/mapper/"${i##*/}"-part4
  3. Load ZFS kernel module

    modprobe zfs
  4. Create boot pool

    # shellcheck disable=SC2046
    zpool create -o compatibility=legacy  \
        -o ashift=12 \
        -o autotrim=on \
        -O acltype=posixacl \
        -O canmount=off \
        -O devices=off \
        -O normalization=formD \
        -O relatime=on \
        -O xattr=sa \
        -O mountpoint=/boot \
        -R "${MNT}" \
        bpool \
               mirror \
        $(for i in ${DISK}; do
           printf '%s ' "${i}-part2";

    If not using a multi-disk setup, remove mirror.

    You should not need to customize any of the options for the boot pool.

    GRUB does not support all of the zpool features. See spa_feature_names in grub-core/fs/zfs/zfs.c. This step creates a separate boot pool for /boot with the features limited to only those that GRUB supports, allowing the root pool to use any/all features.

  5. Create root pool

    # shellcheck disable=SC2046
    zpool create \
        -o ashift=12 \
        -o autotrim=on \
        -R "${MNT}" \
        -O acltype=posixacl \
        -O canmount=off \
        -O compression=zstd \
        -O dnodesize=auto \
        -O normalization=formD \
        -O relatime=on \
        -O xattr=sa \
        -O mountpoint=/ \
        rpool \
        mirror \
       $(for i in ${DISK}; do
          printf '%s ' "${i}-part3";

    If not using a multi-disk setup, remove mirror.

  6. Create root system container:

    • Unencrypted

      zfs create \
       -o canmount=off \
       -o mountpoint=none \
    • Encrypted:

      Avoid ZFS send/recv when using native encryption, see `a ZFS developer's comment on this issue`__ and `this spreadsheet of bugs`__. A LUKS-based guide has yet to be written. Once compromised, changing password will not keep your data safe. See zfs-change-key(8) for more info

      zfs create \
        -o canmount=off \
               -o mountpoint=none \
               -o encryption=on \
               -o keylocation=prompt \
               -o keyformat=passphrase \

    You can automate this step (insecure) with: echo POOLPASS | zfs create ....

    Create system datasets, manage mountpoints with mountpoint=legacy

    zfs create -o canmount=noauto -o mountpoint=/  rpool/archlinux/root
    zfs mount rpool/archlinux/root
    zfs create -o mountpoint=legacy rpool/archlinux/home
    mkdir "${MNT}"/home
    mount -t zfs rpool/archlinux/home "${MNT}"/home
    zfs create -o mountpoint=legacy  rpool/archlinux/var
    zfs create -o mountpoint=legacy rpool/archlinux/var/lib
    zfs create -o mountpoint=legacy rpool/archlinux/var/log
    zfs create -o mountpoint=none bpool/archlinux
    zfs create -o mountpoint=legacy bpool/archlinux/root
    mkdir "${MNT}"/boot
    mount -t zfs bpool/archlinux/root "${MNT}"/boot
    mkdir -p "${MNT}"/var/log
    mkdir -p "${MNT}"/var/lib
    mount -t zfs rpool/archlinux/var/lib "${MNT}"/var/lib
    mount -t zfs rpool/archlinux/var/log "${MNT}"/var/log
  7. Format and mount ESP

    for i in ${DISK}; do
     mkfs.vfat -n EFI "${i}"-part1
     mkdir -p "${MNT}"/boot/efis/"${i##*/}"-part1
     mount -t vfat -o iocharset=iso8859-1 "${i}"-part1 "${MNT}"/boot/efis/"${i##*/}"-part1
    mkdir -p "${MNT}"/boot/efi
    mount -t vfat -o iocharset=iso8859-1 "$(echo "${DISK}" | sed "s|^ *||"  | cut -f1 -d' '|| true)"-part1 "${MNT}"/boot/efi

System Configuration

  1. Download and extract minimal Arch Linux root filesystem:

    apk add curl
    curl --fail-early --fail -L \ \
    -o rootfs.tar.gz
    curl --fail-early --fail -L \ \
    -o rootfs.tar.gz.sig
    apk add gnupg
    gpg --auto-key-retrieve --keyserver hkps:// --verify rootfs.tar.gz.sig
    ln -s "${MNT}" "${MNT}"/root.x86_64
    tar x  -C "${MNT}" -af rootfs.tar.gz root.x86_64
  2. Enable community repo

    sed -i '/edge/d' /etc/apk/repositories
    sed -i -E 's/#(.*)community/\1community/' /etc/apk/repositories
  3. Generate fstab:

    apk add arch-install-scripts
    genfstab -t PARTUUID "${MNT}" \
    | grep -v swap \
    | sed "s|vfat.*rw|vfat rw,x-systemd.idle-timeout=1min,x-systemd.automount,noauto,nofail|" \
    > "${MNT}"/etc/fstab
  4. Chroot

    cp /etc/resolv.conf "${MNT}"/etc/resolv.conf
    for i in /dev /proc /sys; do mkdir -p "${MNT}"/"${i}"; mount --rbind "${i}" "${MNT}"/"${i}"; done
    chroot "${MNT}" /usr/bin/env DISK="${DISK}" bash
  5. Add archzfs repo to pacman config

    pacman-key --init
    pacman-key --refresh-keys
    pacman-key --populate
    curl --fail-early --fail -L \
    |  pacman-key -a - --gpgdir /etc/pacman.d/gnupg
    pacman-key \
    --lsign-key \
    --gpgdir /etc/pacman.d/gnupg \
    tee -a /etc/pacman.d/mirrorlist-archzfs <<- 'EOF'
    ## See
    ## France
    #,Server =$repo/$arch
    ## Germany
    #,Server =$repo/$arch
    #,Server =$repo/$arch
    ## India
    #,Server =$repo/$arch
    ## United States
    #,Server =$repo/$arch
    tee -a /etc/pacman.conf <<- 'EOF'
    #Include = /etc/pacman.d/mirrorlist-archzfs
    #,Include = /etc/pacman.d/mirrorlist-archzfs
    # this #, prefix is a workaround for ci/cd tests
    # remove them
    sed -i 's|#,||' /etc/pacman.d/mirrorlist-archzfs
    sed -i 's|#,||' /etc/pacman.conf
    sed -i 's|^#||' /etc/pacman.d/mirrorlist
  6. Install base packages:

    pacman -Sy
    pacman -S --noconfirm mg mandoc grub efibootmgr mkinitcpio
    kernel_compatible_with_zfs="$(pacman -Si zfs-linux \
    | grep 'Depends On' \
    | sed "s|.*linux=||" \
    | awk '{ print $1 }')"
    pacman -U --noconfirm"${kernel_compatible_with_zfs}"-x86_64.pkg.tar.zst
  7. Install zfs packages:

    pacman -S --noconfirm zfs-linux zfs-utils
  8. Configure mkinitcpio:

    sed -i 's|filesystems|zfs filesystems|' /etc/mkinitcpio.conf
    mkinitcpio -P
  9. For physical machine, install firmware

    pacman -S linux-firmware intel-ucode amd-ucode
  10. Enable internet time synchronisation:

    systemctl enable systemd-timesyncd
  11. Generate host id:

    zgenhostid -f -o /etc/hostid
  12. Generate locales:

    echo "en_US.UTF-8 UTF-8" >> /etc/locale.gen
  13. Set locale, keymap, timezone, hostname

    rm -f /etc/localtime
    systemd-firstboot \
    --force \
    --locale=en_US.UTF-8 \
    --timezone=Etc/UTC \
    --hostname=testhost \
  14. Set root passwd

    printf 'root:yourpassword' | chpasswd


  1. Apply GRUB workaround

    echo 'export ZPOOL_VDEV_NAME_PATH=YES' >> /etc/profile.d/
    # shellcheck disable=SC1091
    . /etc/profile.d/
    # GRUB fails to detect rpool name, hard code as "rpool"
    sed -i "s|rpool=.*|rpool=rpool|"  /etc/grub.d/10_linux

    This workaround needs to be applied for every GRUB update, as the update will overwrite the changes.

  2. Install GRUB:

    mkdir -p /boot/efi/archlinux/grub-bootdir/i386-pc/
    mkdir -p /boot/efi/archlinux/grub-bootdir/x86_64-efi/
    for i in ${DISK}; do
     grub-install --target=i386-pc --boot-directory \
         /boot/efi/archlinux/grub-bootdir/i386-pc/  "${i}"
    grub-install --target x86_64-efi --boot-directory \
     /boot/efi/archlinux/grub-bootdir/x86_64-efi/ --efi-directory \
     /boot/efi --bootloader-id archlinux --removable
    if test -d /sys/firmware/efi/efivars/; then
       grub-install --target x86_64-efi --boot-directory \
        /boot/efi/archlinux/grub-bootdir/x86_64-efi/ --efi-directory \
        /boot/efi --bootloader-id archlinux
  3. Import both bpool and rpool at boot:

    echo 'GRUB_CMDLINE_LINUX="zfs_import_dir=/dev/"' >> /etc/default/grub
  4. Generate GRUB menu:

    mkdir -p /boot/grub
    grub-mkconfig -o /boot/grub/grub.cfg
    cp /boot/grub/grub.cfg \
    cp /boot/grub/grub.cfg \
  5. For both legacy and EFI booting: mirror ESP content:

    espdir=$(mktemp -d)
    find /boot/efi/ -maxdepth 1 -mindepth 1 -type d -print0 \
    | xargs -t -0I '{}' cp -r '{}' "${espdir}"
    find "${espdir}" -maxdepth 1 -mindepth 1 -type d -print0 \
    | xargs -t -0I '{}' sh -vxc "find /boot/efis/ -maxdepth 1 -mindepth 1 -type d -print0 | xargs -t -0I '[]' cp -r '{}' '[]'"
  6. Exit chroot

  7. Unmount filesystems and create initial system snapshot You can later create a boot environment from this snapshot. See Root on ZFS maintenance page.

    umount -Rl "${MNT}"
    zfs snapshot -r rpool@initial-installation
    zfs snapshot -r bpool@initial-installation
  8. Export all pools

    zpool export -a
  9. Reboot