Release v2.2.2 is EOL. Refer to for current documentation.

Jammy (22.04) UEFI#

This guide can be used to install Ubuntu onto a single disk with or without ZFS encryption.

The end result will be a pristine Ubuntu install with no GUI or anything other than the base system. You'll be able to install ubuntu-desktop, ubuntu-server-minimal or whatever takes your fancy afterwards.

It assumes the following:

  • Your system uses UEFI to boot

  • Your system is x86_64

  • You're mildly comfortable with ZFS, EFI and discovering system facts on your own (lsblk, dmesg, gdisk, ...)

Download the latest Ubuntu Desktop Jammy (22.04) Live image, write it to a USB drive and boot your system in EFI mode. You can use the server installation media if you want, although instructions are provided for installation using the desktop installer live session.

Configure Live Environment#

Open a root shell#

Open a terminal on the live installer session, then:

sudo -i

Confirm EFI support:

# dmesg | grep -i efivars
[    0.301784] Registered efivars operations

Source /etc/os-release#

The file /etc/os-release defines variables that describe the running distribution. In particular, the $ID variable defined within can be used as a short name for the filesystem that will hold this installation.

source /etc/os-release
export ID

Install helpers#

apt update
apt install debootstrap gdisk zfsutils-linux

Generate /etc/hostid#

zgenhostid -f 0x00bab10c

Define disk variables#

For convenience and to reduce the likelihood of errors, set environment variables that refer to the devices that will be configured during the setup.

For many users, it is most convenient to place boot files (i.e., ZFSBootMenu and any loader responsible for launching it) on the the same disk that will hold the ZFS pool. However, some users may wish to dedicate an entire disk to the ZFS pool or create a multi-disk pool. A USB flash drive provides a convenient location for the boot partition. Fortunately, this alternative configuration is easily realized by simply defining a few environment variables differently.

Verify your target disk devices with lsblk. /dev/sda, /dev/sdb and /dev/nvme0n1 used below are examples.

First, define variables that refer to the disk and partition number that will hold boot files:

export BOOT_DISK="/dev/sda"
export BOOT_PART="1"

Next, define variables that refer to the disk and partition number that will hold the ZFS pool:

export POOL_DISK="/dev/sda"
export POOL_PART="2"

Disk preparation#

Wipe partitions#

zpool labelclear -f "$POOL_DISK"

wipefs -a "$POOL_DISK"
wipefs -a "$BOOT_DISK"

sgdisk --zap-all "$POOL_DISK"
sgdisk --zap-all "$BOOT_DISK"

Create EFI boot partition#

sgdisk -n "${BOOT_PART}:1m:+512m" -t "${BOOT_PART}:ef00" "$BOOT_DISK"

Create zpool partition#

sgdisk -n "${POOL_PART}:0:-10m" -t "${POOL_PART}:bf00" "$POOL_DISK"

ZFS pool creation#

Create the zpool#

zpool create -f -o ashift=12 \
 -O compression=lz4 \
 -O acltype=posixacl \
 -O xattr=sa \
 -O relatime=on \
 -o autotrim=on \
 -o compatibility=openzfs-2.1-linux \
 -m none zroot "$POOL_DEVICE"


The option -o compatibility=openzfs-2.1-linux ensures that the pool is created only with feature flags supported by the current ZFSBootMenu binary release. If you plan on building a custom ZFSBootMenu image that you will keep synchronized with your host, the compatibility option may be omitted.

Binary releases of ZFSBootMenu are generally built with the latest stable version of ZFS. Future releases of ZFSBootMenu may therefore support newer feature sets. Check project release notes prior to updating or removing compatibility options and upgrading your system pool.

Create initial file systems#

zfs create -o mountpoint=none zroot/ROOT
zfs create -o mountpoint=/ -o canmount=noauto zroot/ROOT/${ID}
zfs create -o mountpoint=/home zroot/home

zpool set bootfs=zroot/ROOT/${ID} zroot


It is important to set the property canmount=noauto on any file systems with mountpoint=/ (that is, on any additional boot environments you create). Without this property, the OS will attempt to automount all ZFS file systems and fail when multiple file systems attempt to mount at /; this will prevent your system from booting. Automatic mounting of / is not required because the root file system is explicitly mounted in the boot process.

Also note that, unlike many ZFS properties, canmount is not inheritable. Therefore, setting canmount=noauto on zroot/ROOT is not sufficient, as any subsequent boot environments you create will default to canmount=on. It is necessary to explicitly set the canmount=noauto on every boot environment you create.

Export, then re-import with a temporary mountpoint of /mnt#

zpool export zroot
zpool import -N -R /mnt zroot
zfs mount zroot/ROOT/${ID}
zfs mount zroot/home

Verify that everything is mounted correctly#

# mount | grep mnt
zroot/ROOT/ubuntu on /mnt type zfs (rw,relatime,xattr,posixacl)
zroot/home on /mnt/home type zfs (rw,relatime,xattr,posixacl)

Install Ubuntu#

debootstrap jammy /mnt

Copy files into the new install#

cp /etc/hostid /mnt/etc
cp /etc/resolv.conf /mnt/etc

Chroot into the new OS#

mount -t proc proc /mnt/proc
mount -t sysfs sys /mnt/sys
mount -B /dev /mnt/dev
mount -t devpts pts /mnt/dev/pts
chroot /mnt /bin/bash

Basic Ubuntu Configuration#

Set a hostname#

echo 'YOURHOSTNAME' > /etc/hostname
echo -e '\tYOURHOSTNAME' >> /etc/hosts

Set a root password#


Configure apt. Use other mirrors if you prefer.

cat <<EOF > /etc/apt/sources.list
# Uncomment the deb-src entries if you need source packages

deb jammy main restricted universe multiverse
# deb-src jammy main restricted universe multiverse

deb jammy-updates main restricted universe multiverse
# deb-src jammy-updates main restricted universe multiverse

deb jammy-security main restricted universe multiverse
# deb-src jammy-security main restricted universe multiverse

deb jammy-backports main restricted universe multiverse
# deb-src jammy-backports main restricted universe multiverse

deb jammy partner
# deb-src jammy partner

Update the repository cache and system#

apt update
apt upgrade

Install additional base packages#

apt install --no-install-recommends linux-generic locales keyboard-configuration console-setup


The --no-install-recommends flag is used here to avoid installing recommended, but not strictly needed, packages (including grub2).

Configure packages to customize local and console properties#

dpkg-reconfigure locales tzdata keyboard-configuration console-setup


You should always enable the en_US.UTF-8 locale because some programs require it.

ZFS Configuration#

Install required packages#

apt install dosfstools zfs-initramfs zfsutils-linux

Enable systemd ZFS services#

systemctl enable
systemctl enable zfs-import-cache
systemctl enable zfs-mount
systemctl enable

Configure initramfs-tools#

No required steps

Rebuild the initramfs#

update-initramfs -c -k all

Install and configure ZFSBootMenu#

Set ZFSBootMenu properties on datasets#

Assign command-line arguments to be used when booting the final kernel. Because ZFS properties are inherited, assign the common properties to the ROOT dataset so all children will inherit common arguments by default.

zfs set org.zfsbootmenu:commandline="quiet loglevel=4" zroot/ROOT

Create a vfat filesystem#

mkfs.vfat -F32 "$BOOT_DEVICE"

Create an fstab entry and mount#

cat << EOF >> /etc/fstab
$( blkid | grep "$BOOT_DEVICE" | cut -d ' ' -f 2 ) /boot/efi vfat defaults 0 0

mkdir -p /boot/efi
mount /boot/efi

Install ZFSBootMenu#

apt install curl

Fetch a prebuilt ZFSBootMenu EFI executable, saving it to the EFI system partition:

mkdir -p /boot/efi/EFI/ZBM
curl -o /boot/efi/EFI/ZBM/VMLINUZ.EFI -L

Configure EFI boot entries#

mount -t efivarfs efivarfs /sys/firmware/efi/efivars
apt install efibootmgr
efibootmgr -c -d "$BOOT_DISK" -p "$BOOT_PART" \
  -L "ZFSBootMenu (Backup)" \

efibootmgr -c -d "$BOOT_DISK" -p "$BOOT_PART" \
  -L "ZFSBootMenu" \

See also

Some systems can have issues with EFI boot entries. If you reboot and do not see the above entries in your EFI selection screen (usually accessible through an F key during POST), you might need to use a well-known EFI file name. See Portable EFI for help with this. Your existing ESP can be used, in place of an external USB drive.

Refer to zbm-kcl.8 and zfsbootmenu.7 for details on configuring the boot-time behavior of ZFSBootMenu.

Prepare for first boot#

Exit the chroot, unmount everything#

umount -n -R /mnt

Export the zpool and reboot#

zpool export zroot