Ubuntu 22.04 Root on ZFS for Raspberry Pi

Overview

Note

These are beta instructions. The author still needs to test them. Additionally, it may be possible to use U-Boot now, which would eliminate some of the customizations.

Caution

  • This HOWTO uses a whole physical disk.

  • Backup your data. Any existing data will be lost.

System Requirements

4 GiB of memory is recommended. Do not use deduplication, as it needs massive amounts of RAM. Enabling deduplication is a permanent change that cannot be easily reverted.

A Raspberry Pi 3 B/B+ would probably work (as the Pi 3 is 64-bit, though it has less RAM), but has not been tested. Please report your results (good or bad) using the issue link below.

Support

If you need help, reach out to the community using the Mailing Lists or IRC at #zfsonlinux on Libera Chat. If you have a bug report or feature request related to this HOWTO, please file a new issue and mention @rlaager.

Contributing

  1. Fork and clone: https://github.com/openzfs/openzfs-docs

  2. Install the tools:

    sudo apt install python3-pip
    
    pip3 install -r docs/requirements.txt
    
    # Add ~/.local/bin to your $PATH, e.g. by adding this to ~/.bashrc:
    PATH=$HOME/.local/bin:$PATH
    
  3. Make your changes.

  4. Test:

    cd docs
    make html
    sensible-browser _build/html/index.html
    
  5. git commit --signoff to a branch, git push, and create a pull request. Mention @rlaager.

Encryption

WARNING: Encryption has not yet been tested on the Raspberry Pi.

This guide supports three different encryption options: unencrypted, ZFS native encryption, and LUKS. With any option, all ZFS features are fully available.

Unencrypted does not encrypt anything, of course. With no encryption happening, this option naturally has the best performance.

ZFS native encryption encrypts the data and most metadata in the root pool. It does not encrypt dataset or snapshot names or properties. The boot pool is not encrypted at all, but it only contains the bootloader, kernel, and initrd. (Unless you put a password in /etc/fstab, the initrd is unlikely to contain sensitive data.) The system cannot boot without the passphrase being entered at the console. Performance is good. As the encryption happens in ZFS, even if multiple disks (mirror or raidz topologies) are used, the data only has to be encrypted once.

LUKS encrypts almost everything. The only unencrypted data is the bootloader, kernel, and initrd. The system cannot boot without the passphrase being entered at the console. Performance is good, but LUKS sits underneath ZFS, so if multiple disks (mirror or raidz topologies) are used, the data has to be encrypted once per disk.

USB Disks

The Raspberry Pi 4 runs much faster using a USB Solid State Drive (SSD) than a microSD card. These instructions can also be used to install Ubuntu on a USB-connected SSD or other USB disk. USB disks have three requirements that do not apply to microSD cards:

  1. The Raspberry Pi’s Bootloader EEPROM must be dated 2020-09-03 or later.

    To check the bootloader version, power up the Raspberry Pi without an SD card inserted or a USB boot device attached; the date will be on the bootloader line. (If you do not see the bootloader line, the bootloader is too old.) Alternatively, run sudo rpi-eeprom-update on an existing OS on the Raspberry Pi (which on Ubuntu requires apt install rpi-eeprom).

    If needed, the bootloader can be updated from an existing OS on the Raspberry Pi using rpi-eeprom-update -a and rebooting. For other options, see Updating the Bootloader.

  2. The Raspberry Pi must configured for USB boot. The bootloader will show a boot line; if order includes 4, USB boot is enabled.

    If not already enabled, it can be enabled from an existing OS on the Raspberry Pi using rpi-eeprom-config -e: set BOOT_ORDER=0xf41 and reboot to apply the change. On subsequent reboots, USB boot will be enabled.

    Otherwise, it can be enabled without an existing OS as follows:

    • Download the Raspberry Pi Imager Utility.

    • Flash the USB Boot image to a microSD card. The USB Boot image is listed under Bootload in the Misc utility images folder.

    • Boot the Raspberry Pi from the microSD card. USB Boot should be enabled automatically.

  3. U-Boot on Ubuntu 20.04 does not seem to support the Raspberry Pi USB. Ubuntu 20.10 may work. As a work-around, the Raspberry Pi bootloader is configured to directly boot Linux. For this to work, the Linux kernel must not be compressed. These instructions decompress the kernel and add a script to /etc/kernel/postinst.d to handle kernel upgrades.

Step 1: Disk Formatting

The commands in this step are run on the system other than the Raspberry Pi.

This guide has you go to some extra work so that the stock ext4 partition can be deleted.

  1. Download and unpack the official image:

    curl -O https://cdimage.ubuntu.com/releases/22.04/release/ubuntu-22.04.1-preinstalled-server-arm64+raspi.img.xz
    xz -d ubuntu-22.04.1-preinstalled-server-arm64+raspi.img.xz
    
    # or combine them to decompress as you download:
    curl https://cdimage.ubuntu.com/releases/22.04/release/ubuntu-22.04.1-preinstalled-server-arm64+raspi.img.xz | \
        xz -d > ubuntu-22.04.1-preinstalled-server-arm64+raspi.img
    
  2. Dump the partition table for the image:

    sfdisk -d ubuntu-22.04.1-preinstalled-server-arm64+raspi.img
    

    That will output this:

    label: dos
    label-id: 0x638274e3
    device: ubuntu-22.04.1-preinstalled-server-arm64+raspi.img
    unit: sectors
    
    <name>.img1 : start=        2048, size=      524288, type=c, bootable
    <name>.img2 : start=      526336, size=     7193932, type=83
    

    The important numbers are 524288 and 7193932. Store those in variables:

    BOOT=524288
    ROOT=7193932
    
  3. Create a partition script:

    cat > partitions << EOF
    label: dos
    unit: sectors
    
    1 : start=  2048,  size=$BOOT,  type=c, bootable
    2 : start=$((2048+BOOT)),  size=$ROOT, type=83
    3 : start=$((2048+BOOT+ROOT)), size=$ROOT, type=83
    EOF
    
  4. Connect the disk:

    Connect the disk to a machine other than the target Raspberry Pi. If any filesystems are automatically mounted (e.g. by GNOME) unmount them. Determine the device name. For SD, the device name is almost certainly /dev/mmcblk0. For USB SSDs, the device name is /dev/sdX, where X is a lowercase letter. lsblk can help determine the device name. Set the DISK environment variable to the device name:

    DISK=/dev/mmcblk0    # microSD card
    DISK=/dev/sdX        # USB disk
    

    Because partitions are named differently for /dev/mmcblk0 and /dev/sdX devices, set a second variable used when working with partitions:

    export DISKP=${DISK}p # microSD card
    export DISKP=${DISK}  # USB disk ($DISKP == $DISK for /dev/sdX devices)
    

    Hint: microSD cards connected using a USB reader also have /dev/sdX names.

    WARNING: The following steps destroy the existing data on the disk. Ensure DISK and DISKP are correct before proceeding.

  5. Ensure swap partitions are not in use:

    swapon -v
    # If a partition is in use from the disk, disable it:
    sudo swapoff THAT_PARTITION
    
  6. Clear old ZFS labels:

    sudo zpool labelclear -f ${DISK}
    

    If a ZFS label still exists from a previous system/attempt, expanding the pool will result in an unbootable system.

    Hint: If you do not already have the ZFS utilities installed, you can install them with: sudo apt install zfsutils-linux Alternatively, you can zero the entire disk with: sudo dd if=/dev/zero of=${DISK} bs=1M status=progress

  7. Delete existing partitions:

    echo "label: dos" | sudo sfdisk ${DISK}
    sudo partprobe
    ls ${DISKP}*
    

    Make sure there are no partitions, just the file for the disk itself. This step is not strictly necessary; it exists to catch problems.

  8. Create the partitions:

    sudo sfdisk $DISK < partitions
    
  9. Loopback mount the image:

    IMG=$(sudo losetup -fP --show \
              ubuntu-22.04.1-preinstalled-server-arm64+raspi.img)
    
  10. Copy the bootloader data:

    sudo dd if=${IMG}p1 of=${DISKP}1 bs=1M
    
  11. Clear old label(s) from partition 2:

    sudo wipefs -a ${DISKP}2
    

    If a filesystem with the writable label from the Ubuntu image is still present in partition 2, the system will not boot initially.

  12. Copy the root filesystem data:

    # NOTE: the destination is p3, not p2.
    sudo dd if=${IMG}p2 of=${DISKP}3 bs=1M status=progress conv=fsync
    
  13. Unmount the image:

    sudo losetup -d $IMG
    
  14. If setting up a USB disk:

    Decompress the kernel:

    sudo -sE
    
    MNT=$(mktemp -d /mnt/XXXXXXXX)
    mkdir -p $MNT/boot $MNT/root
    mount ${DISKP}1 $MNT/boot
    mount ${DISKP}3 $MNT/root
    
    zcat -qf $MNT/boot/vmlinuz >$MNT/boot/vmlinux
    

    Modify boot config:

    cat >> $MNT/boot/usercfg.txt << EOF
    kernel=vmlinux
    initramfs initrd.img followkernel
    boot_delay
    EOF
    

    Create a script to automatically decompress the kernel after an upgrade:

    cat >$MNT/root/etc/kernel/postinst.d/zz-decompress-kernel << 'EOF'
    #!/bin/sh
    
    set -eu
    
    echo "Updating decompressed kernel..."
    [ -e /boot/firmware/vmlinux ] && \
        cp /boot/firmware/vmlinux /boot/firmware/vmlinux.bak
    vmlinuxtmp=$(mktemp /boot/firmware/vmlinux.XXXXXXXX)
    zcat -qf /boot/vmlinuz > "$vmlinuxtmp"
    mv "$vmlinuxtmp" /boot/firmware/vmlinux
    EOF
    
    chmod +x $MNT/root/etc/kernel/postinst.d/zz-decompress-kernel
    

    Cleanup:

    umount $MNT/*
    rm -rf $MNT
    exit
    
  15. Boot the Raspberry Pi.

    Move the SD/USB disk to the Raspberry Pi. Boot it and login (e.g. via SSH) with ubuntu as the username and password. If you are using SSH, note that it takes a little bit for cloud-init to enable password logins on the first boot. Set a new password when prompted and login again using that password. If you have your local SSH configured to use ControlPersist, you will have to kill the existing SSH process before logging in the second time.

Step 2: Setup ZFS

  1. Become root:

    sudo -i
    
  2. Set the DISK and DISKP variables again:

    DISK=/dev/mmcblk0    # microSD card
    DISKP=${DISK}p       # microSD card
    
    DISK=/dev/sdX        # USB disk
    DISKP=${DISK}        # USB disk
    

    WARNING: Device names can change when moving a device to a different computer or switching the microSD card from a USB reader to a built-in slot. Double check the device name before continuing.

  3. Install ZFS:

    apt update
    
    apt install pv zfs-initramfs
    

    Note: Since this is the first boot, you may get Waiting for cache lock because unattended-upgrades is running in the background. Wait for it to finish.

  4. Create the root pool:

    Choose one of the following options:

    • Unencrypted:

      zpool create \
          -o ashift=12 \
          -O acltype=posixacl -O canmount=off -O compression=lz4 \
          -O dnodesize=auto -O normalization=formD -O relatime=on \
          -O xattr=sa -O mountpoint=/ -R /mnt \
          rpool ${DISKP}2
      

    WARNING: Encryption has not yet been tested on the Raspberry Pi.

    • ZFS native encryption:

      zpool create \
          -o ashift=12 \
          -O encryption=on \
          -O keylocation=prompt -O keyformat=passphrase \
          -O acltype=posixacl -O canmount=off -O compression=lz4 \
          -O dnodesize=auto -O normalization=formD -O relatime=on \
          -O xattr=sa -O mountpoint=/ -R /mnt \
          rpool ${DISKP}2
      
    • LUKS:

      cryptsetup luksFormat -c aes-xts-plain64 -s 512 -h sha256 ${DISKP}2
      cryptsetup luksOpen ${DISK}-part4 luks1
      zpool create \
          -o ashift=12 \
          -O acltype=posixacl -O canmount=off -O compression=lz4 \
          -O dnodesize=auto -O normalization=formD -O relatime=on \
          -O xattr=sa -O mountpoint=/ -R /mnt \
          rpool /dev/mapper/luks1
      

    Notes:

    • The use of ashift=12 is recommended here because many drives today have 4 KiB (or larger) physical sectors, even though they present 512 B logical sectors. Also, a future replacement drive may have 4 KiB physical sectors (in which case ashift=12 is desirable) or 4 KiB logical sectors (in which case ashift=12 is required).

    • Setting -O acltype=posixacl enables POSIX ACLs globally. If you do not want this, remove that option, but later add -o acltype=posixacl (note: lowercase “o”) to the zfs create for /var/log, as journald requires ACLs Also, disabling ACLs apparently breaks umask handling with NFSv4.

    • Setting normalization=formD eliminates some corner cases relating to UTF-8 filename normalization. It also implies utf8only=on, which means that only UTF-8 filenames are allowed. If you care to support non-UTF-8 filenames, do not use this option. For a discussion of why requiring UTF-8 filenames may be a bad idea, see The problems with enforced UTF-8 only filenames.

    • recordsize is unset (leaving it at the default of 128 KiB). If you want to tune it (e.g. -O recordsize=1M), see these various blog posts.

    • Setting relatime=on is a middle ground between classic POSIX atime behavior (with its significant performance impact) and atime=off (which provides the best performance by completely disabling atime updates). Since Linux 2.6.30, relatime has been the default for other filesystems. See RedHat’s documentation for further information.

    • Setting xattr=sa vastly improves the performance of extended attributes. Inside ZFS, extended attributes are used to implement POSIX ACLs. Extended attributes can also be used by user-space applications. They are used by some desktop GUI applications. They can be used by Samba to store Windows ACLs and DOS attributes; they are required for a Samba Active Directory domain controller. Note that xattr=sa is Linux-specific. If you move your xattr=sa pool to another OpenZFS implementation besides ZFS-on-Linux, extended attributes will not be readable (though your data will be). If portability of extended attributes is important to you, omit the -O xattr=sa above. Even if you do not want xattr=sa for the whole pool, it is probably fine to use it for /var/log.

    • Make sure to include the -part4 portion of the drive path. If you forget that, you are specifying the whole disk, which ZFS will then re-partition, and you will lose the bootloader partition(s).

    • ZFS native encryption now defaults to aes-256-gcm.

    • For LUKS, the key size chosen is 512 bits. However, XTS mode requires two keys, so the LUKS key is split in half. Thus, -s 512 means AES-256.

    • Your passphrase will likely be the weakest link. Choose wisely. See section 5 of the cryptsetup FAQ for guidance.

Step 3: System Installation

  1. Create a filesystem dataset to act as a container:

    zfs create -o canmount=off -o mountpoint=none rpool/ROOT
    
  2. Create a filesystem dataset for the root filesystem:

    UUID=$(dd if=/dev/urandom bs=1 count=100 2>/dev/null |
        tr -dc 'a-z0-9' | cut -c-6)
    
    zfs create -o canmount=noauto -o mountpoint=/ \
        -o com.ubuntu.zsys:bootfs=yes \
        -o com.ubuntu.zsys:last-used=$(date +%s) rpool/ROOT/ubuntu_$UUID
    zfs mount rpool/ROOT/ubuntu_$UUID
    

    With ZFS, it is not normally necessary to use a mount command (either mount or zfs mount). This situation is an exception because of canmount=noauto.

  3. Create datasets:

    zfs create -o com.ubuntu.zsys:bootfs=no -o canmount=off \
        rpool/ROOT/ubuntu_$UUID/usr
    zfs create -o com.ubuntu.zsys:bootfs=no -o canmount=off \
        rpool/ROOT/ubuntu_$UUID/var
    zfs create rpool/ROOT/ubuntu_$UUID/var/lib
    zfs create rpool/ROOT/ubuntu_$UUID/var/log
    zfs create rpool/ROOT/ubuntu_$UUID/var/spool
    
    zfs create -o canmount=off -o mountpoint=/ \
        rpool/USERDATA
    zfs create -o com.ubuntu.zsys:bootfs-datasets=rpool/ROOT/ubuntu_$UUID \
        -o canmount=on -o mountpoint=/root \
        rpool/USERDATA/root_$UUID
    chmod 700 /mnt/root
    

    The datasets below are optional, depending on your preferences and/or software choices.

    If you wish to separate these to exclude them from snapshots:

    zfs create rpool/ROOT/ubuntu_$UUID/var/cache
    zfs create rpool/ROOT/ubuntu_$UUID/var/lib/nfs
    zfs create rpool/ROOT/ubuntu_$UUID/var/tmp
    chmod 1777 /mnt/var/tmp
    

    If desired (the Ubuntu installer creates these):

    zfs create rpool/ROOT/ubuntu_$UUID/var/lib/apt
    zfs create rpool/ROOT/ubuntu_$UUID/var/lib/dpkg
    

    If you use /srv on this system:

    zfs create -o com.ubuntu.zsys:bootfs=no \
        rpool/ROOT/ubuntu_$UUID/srv
    

    If you use /usr/local on this system:

    zfs create rpool/ROOT/ubuntu_$UUID/usr/local
    

    If this system will have games installed:

    zfs create rpool/ROOT/ubuntu_$UUID/var/games
    

    If this system will have a GUI:

    zfs create rpool/ROOT/ubuntu_$UUID/var/lib/AccountsService
    zfs create rpool/ROOT/ubuntu_$UUID/var/lib/NetworkManager
    

    If this system will use Docker (which manages its own datasets & snapshots):

    zfs create rpool/ROOT/ubuntu_$UUID/var/lib/docker
    

    If this system will store local email in /var/mail:

    zfs create rpool/ROOT/ubuntu_$UUID/var/mail
    

    If this system will use Snap packages:

    zfs create rpool/ROOT/ubuntu_$UUID/var/snap
    

    If you use /var/www on this system:

    zfs create rpool/ROOT/ubuntu_$UUID/var/www
    

    For a mirror or raidz topology, create a dataset for /boot/grub:

    zfs create -o com.ubuntu.zsys:bootfs=no bpool/grub
    

    A tmpfs is recommended later, but if you want a separate dataset for /tmp:

    zfs create -o com.ubuntu.zsys:bootfs=no \
        rpool/ROOT/ubuntu_$UUID/tmp
    chmod 1777 /mnt/tmp
    

    The primary goal of this dataset layout is to separate the OS from user data. This allows the root filesystem to be rolled back without rolling back user data.

    If you do nothing extra, /tmp will be stored as part of the root filesystem. Alternatively, you can create a separate dataset for /tmp, as shown above. This keeps the /tmp data out of snapshots of your root filesystem. It also allows you to set a quota on rpool/tmp, if you want to limit the maximum space used. Otherwise, you can use a tmpfs (RAM filesystem) later.

  4. Optional: Ignore synchronous requests:

    microSD cards are relatively slow. If you want to increase performance (especially when installing packages) at the cost of some safety, you can disable flushing of synchronous requests (e.g. fsync(), O_[D]SYNC):

    Choose one of the following options:

    • For the root filesystem, but not user data:

      zfs set sync=disabled rpool/ROOT
      
    • For everything:

      zfs set sync=disabled rpool
      

    ZFS is transactional, so it will still be crash consistent. However, you should leave sync at its default of standard if this system needs to guarantee persistence (e.g. if it is a database or NFS server).

  5. Copy the system into the ZFS filesystems:

    (cd /; tar -cf - --one-file-system --warning=no-file-ignored .) | \
        pv -p -bs $(du -sxm --apparent-size / | cut -f1)m | \
        (cd /mnt ; tar -x)
    

Step 4: System Configuration

  1. Configure the hostname:

    Replace HOSTNAME with the desired hostname:

    hostname HOSTNAME
    hostname > /mnt/etc/hostname
    vi /mnt/etc/hosts
    
    Add a line:
    127.0.1.1       HOSTNAME
    or if the system has a real name in DNS:
    127.0.1.1       FQDN HOSTNAME
    

    Hint: Use nano if you find vi confusing.

  2. Stop zed:

    systemctl stop zed
    
  3. Bind the virtual filesystems from the running environment to the new ZFS environment and chroot into it:

    mount --make-private --rbind /boot/firmware /mnt/boot/firmware
    mount --make-private --rbind /dev  /mnt/dev
    mount --make-private --rbind /proc /mnt/proc
    mount --make-private --rbind /run  /mnt/run
    mount --make-private --rbind /sys  /mnt/sys
    chroot /mnt /usr/bin/env DISK=$DISK UUID=$UUID bash --login
    
  4. Configure a basic system environment:

    apt update
    

    Even if you prefer a non-English system language, always ensure that en_US.UTF-8 is available:

    dpkg-reconfigure locales
    dpkg-reconfigure tzdata
    
  5. For LUKS installs only, setup /etc/crypttab:

    # cryptsetup is already installed, but this marks it as manually
    # installed so it is not automatically removed.
    apt install --yes cryptsetup
    
    echo luks1 UUID=$(blkid -s UUID -o value ${DISK}-part4) none \
        luks,discard,initramfs > /etc/crypttab
    

    The use of initramfs is a work-around for cryptsetup does not support ZFS.

  6. Optional: Mount a tmpfs to /tmp

    If you chose to create a /tmp dataset above, skip this step, as they are mutually exclusive choices. Otherwise, you can put /tmp on a tmpfs (RAM filesystem) by enabling the tmp.mount unit.

    cp /usr/share/systemd/tmp.mount /etc/systemd/system/
    systemctl enable tmp.mount
    
  7. Setup system groups:

    addgroup --system lpadmin
    addgroup --system sambashare
    
  8. Fix filesystem mount ordering:

    We need to activate zfs-mount-generator. This makes systemd aware of the separate mountpoints, which is important for things like /var/log and /var/tmp. In turn, rsyslog.service depends on var-log.mount by way of local-fs.target and services using the PrivateTmp feature of systemd automatically use After=var-tmp.mount.

    mkdir /etc/zfs/zfs-list.cache
    touch /etc/zfs/zfs-list.cache/rpool
    zed -F &
    

    Force a cache update:

    zfs set canmount=noauto rpool/ROOT/ubuntu_$UUID
    

    Verify that zed updated the cache by making sure this is not empty, which will take a few seconds:

    cat /etc/zfs/zfs-list.cache/rpool
    

    Stop zed:

    fg
    Press Ctrl-C.
    

    Fix the paths to eliminate /mnt:

    sed -Ei "s|/mnt/?|/|" /etc/zfs/zfs-list.cache/*
    
  9. Remove old filesystem from /etc/fstab:

    vi /etc/fstab
    # Remove the old root filesystem line:
    #   LABEL=writable / ext4 ...
    
  10. Configure kernel command line:

    cp /boot/firmware/cmdline.txt /boot/firmware/cmdline.txt.bak
    sed -i "s|root=LABEL=writable rootfstype=ext4|root=ZFS=rpool/ROOT/ubuntu_$UUID|" \
        /boot/firmware/cmdline.txt
    sed -i "s| fixrtc||" /boot/firmware/cmdline.txt
    sed -i "s|$| init_on_alloc=0|" /boot/firmware/cmdline.txt
    

    The fixrtc script is not compatible with ZFS and will cause the boot to hang for 180 seconds.

    The init_on_alloc=0 is to address performance regressions.

  11. Optional (but highly recommended): Make debugging booting easier:

    sed -i "s|$| nosplash|" /boot/firmware/cmdline.txt
    
  12. Reboot:

    exit
    reboot
    

    Wait for the newly installed system to boot normally. Login as ubuntu.

Step 5: First Boot

  1. Become root:

    sudo -i
    
  2. Set the DISK variable again:

    DISK=/dev/mmcblk0    # microSD card
    
    DISK=/dev/sdX        # USB disk
    
  3. Delete the ext4 partition and expand the ZFS partition:

    sfdisk $DISK --delete 3
    echo ", +" | sfdisk --no-reread -N 2 $DISK
    

    Note: This does not automatically expand the pool. That will be happen on reboot.

  4. Create a user account:

    Replace YOUR_USERNAME with your desired username:

    username=YOUR_USERNAME
    
    UUID=$(dd if=/dev/urandom bs=1 count=100 2>/dev/null |
        tr -dc 'a-z0-9' | cut -c-6)
    ROOT_DS=$(zfs list -o name | awk '/ROOT\/ubuntu_/{print $1;exit}')
    zfs create -o com.ubuntu.zsys:bootfs-datasets=$ROOT_DS \
        -o canmount=on -o mountpoint=/home/$username \
        rpool/USERDATA/${username}_$UUID
    adduser $username
    
    cp -a /etc/skel/. /home/$username
    chown -R $username:$username /home/$username
    usermod -a -G adm,cdrom,dip,lpadmin,lxd,plugdev,sambashare,sudo $username
    
  5. Reboot:

    reboot
    

    Wait for the system to boot normally. Login using the account you created.

  6. Become root:

    sudo -i
    
  7. Expand the ZFS pool:

    Verify the pool expanded:

    zfs list rpool
    

    If it did not automatically expand, try to expand it manually:

    DISK=/dev/mmcblk0    # microSD card
    DISKP=${DISK}p       # microSD card
    
    DISK=/dev/sdX        # USB disk
    DISKP=${DISK}        # USB disk
    
    zpool online -e rpool ${DISKP}2
    
  8. Delete the ubuntu user:

    deluser --remove-home ubuntu
    

Step 6: Full Software Installation

  1. Optional: Remove cloud-init:

    vi /etc/netplan/01-netcfg.yaml
    
    network:
      version: 2
      ethernets:
        eth0:
          dhcp4: true
    
    rm /etc/netplan/50-cloud-init.yaml
    apt purge --autoremove ^cloud-init
    rm -rf /etc/cloud
    
  2. Optional: Remove other storage packages:

    apt purge --autoremove bcache-tools btrfs-progs cloud-guest-utils lvm2 \
        mdadm multipath-tools open-iscsi overlayroot xfsprogs
    
  3. Upgrade the minimal system:

    apt dist-upgrade --yes
    
  4. Optional: Install a full GUI environment:

    apt install --yes ubuntu-desktop
    echo dtoverlay=vc4-fkms-v3d >> /boot/firmware/usercfg.txt
    

    Hint: If you are installing a full GUI environment, you will likely want to remove cloud-init as discussed above but manage your network with NetworkManager:

    rm /etc/netplan/*.yaml
    vi /etc/netplan/01-network-manager-all.yaml
    
    network:
      version: 2
      renderer: NetworkManager
    
  5. Optional (but recommended): Disable log compression:

    As /var/log is already compressed by ZFS, logrotate’s compression is going to burn CPU and disk I/O for (in most cases) very little gain. Also, if you are making snapshots of /var/log, logrotate’s compression will actually waste space, as the uncompressed data will live on in the snapshot. You can edit the files in /etc/logrotate.d by hand to comment out compress, or use this loop (copy-and-paste highly recommended):

    for file in /etc/logrotate.d/* ; do
        if grep -Eq "(^|[^#y])compress" "$file" ; then
            sed -i -r "s/(^|[^#y])(compress)/\1#\2/" "$file"
        fi
    done
    
  6. Reboot:

    reboot
    

Step 7: Final Cleanup

  1. Wait for the system to boot normally. Login using the account you created. Ensure the system (including networking) works normally.

  2. Optional: For LUKS installs only, backup the LUKS header:

    sudo cryptsetup luksHeaderBackup /dev/disk/by-id/scsi-SATA_disk1-part4 \
        --header-backup-file luks1-header.dat
    

    Store that backup somewhere safe (e.g. cloud storage). It is protected by your LUKS passphrase, but you may wish to use additional encryption.

    Hint: If you created a mirror or raidz topology, repeat this for each LUKS volume (luks2, etc.).