Apply workarounds

Currently GRUB has multiple compatibility problems with ZFS, especially with regards to newer ZFS features. Workarounds have to be applied.

  1. grub-probe fails to get canonical path

    When persistent device names /dev/disk/by-id/* are used with ZFS, GRUB will fail to resolve the path of the boot pool device. Error:

    # /usr/bin/grub-probe: error: failed to get canonical path of `/dev/virtio-pci-0000:06:00.0-part3'.


    echo 'export ZPOOL_VDEV_NAME_PATH=YES' >> /etc/profile.d/
    source /etc/profile.d/

    Note that sudo will not read /etc/profile and will not pass variables in parent shell. Consider setting the following in /etc/sudoers:

    pacman -S --noconfirm --needed sudo
    echo 'Defaults env_keep += "ZPOOL_VDEV_NAME_PATH"' >> /etc/sudoers
  2. Pool name missing

    See this bug report. Root pool name is missing from root=ZFS=rpool_$INST_UUID/ROOT/default kernel cmdline in generated grub.cfg file.

    A workaround is to replace the pool name detection with zdb command:

    sed -i "s|rpool=.*|rpool=\`zdb -l \${GRUB_DEVICE} \| grep -E '[[:blank:]]name' \| cut -d\\\' -f 2\`|"  /etc/grub.d/10_linux

Install GRUB

  1. Generate initrd:

    rm -f /etc/zfs/zpool.cache
    touch /etc/zfs/zpool.cache
    chmod a-w /etc/zfs/zpool.cache
    chattr +i /etc/zfs/zpool.cache
    mkinitcpio -P
  2. Create GRUB boot directory, in ESP and boot pool:

    mkdir -p /boot/efi/EFI/arch
    mkdir -p /boot/grub

    Boot environment-specific configuration (kernel, etc) is stored in /boot/grub/grub.cfg, enabling rollback.

  3. When in doubt, install both legacy boot and EFI.

  4. If using legacy booting, install GRUB to every disk:

    for i in ${DISK}; do
     grub-install --boot-directory /boot/efi/EFI/arch --target=i386-pc $i
  5. If using EFI:

    grub-install --boot-directory /boot/efi/EFI/arch --efi-directory /boot/efi/
    grub-install --boot-directory /boot/efi/EFI/arch --efi-directory /boot/efi/ --removable
    for i in ${DISK}; do
     efibootmgr -cgp 1 -l "\EFI\arch\grubx64.efi" \
     -L "arch-${i##*/}" -d ${i}
  6. Generate GRUB Menu:

    grub-mkconfig -o /boot/efi/EFI/arch/grub/grub.cfg
    cp /boot/efi/EFI/arch/grub/grub.cfg /boot/grub/grub.cfg
  7. For both legacy and EFI booting: mirror ESP content:

    ESP_MIRROR=$(mktemp -d)
    cp -r /boot/efi/EFI $ESP_MIRROR
    for i in /boot/efis/*; do
     cp -r $ESP_MIRROR/EFI $i

Finish Installation

  1. Exit chroot:

  2. Take a snapshot of the clean installation for future use:

    zfs snapshot -r rpool_$INST_UUID/$INST_ID@install
    zfs snapshot -r bpool_$INST_UUID/$INST_ID@install
  3. Unmount EFI system partition:

    umount /mnt/boot/efi
    umount /mnt/boot/efis/*
  4. Export pools:

    zpool export bpool_$INST_UUID
    zpool export rpool_$INST_UUID
  5. Reboot:


Post installaion

  1. If you have other data pools, generate list of datasets for zfs-mount-generator to mount them at boot:

    DATA_POOL='tank0 tank1'
    # tab-separated zfs properties
    # see /etc/zfs/zed.d/
    export \
    for i in $DATA_POOL; do
    zfs list -H -t filesystem -o $PROPS -r $i > /etc/zfs/zfs-list.cache/$i
  2. After reboot, consider adding a normal user:

    zfs create $(df --output=source /home | tail -n +2)/${myUser}
    useradd -MUd /home/${myUser} -c 'My Name' ${myUser}
    zfs allow -u ${myUser} mount,snapshot,destroy $(df --output=source /home | tail -n +2)/${myUser}
    chown -R ${myUser}:${myUser} /home/${myUser}
    chmod 700 /home/${myUser}
    passwd ${myUser}

    Set up cron job to snapshot user home everyday:

    pacman -S cronie
    systemctl enable --now cronie
    crontab -eu ${myUser}
    #@daily zfs snap $(df --output=source /home/${myUser} | tail -n +2)@$(dd if=/dev/urandom of=/dev/stdout bs=1 count=100 2>/dev/null |tr -dc 'a-z0-9' | cut -c-6)
    zfs list -t snapshot -S creation $(df --output=source /home/${myUser} | tail -n +2)

    Install package groups:

    pacman -Sg        # query package groups
    pacman -S 'gnome'
    pacman -S 'plasma'