ubuntu-17.10-zfs-root

Step 1: Prepare The Install Environment

1.1 Boot the Ubuntu Live CD, select Try Linux, and open a terminal (press Ctrl-Alt-T).

1.2 Setup and update the repositories:

$ sudo apt-add-repository universe
$ sudo apt update

1.3 Optional: Start the OpenSSH server in the Live CD environment:

If you have a second system, using SSH to access the target system can be convenient.

$ passwd
  There is no current password; hit enter at that prompt.
$ sudo apt --yes install openssh-server

Hint: You can find your IP address with ip addr show scope global | grep inet. Then, from your main machine, connect with ssh ubuntu@IP.

1.4 Become root:

$ sudo -i

1.5 Install ZFS in the Live CD environment:

# apt install --yes debootstrap gdisk zfs-initramfs

Step 2: Disk Formatting

2.1 If you are re-using a disk, clear it as necessary:

If the disk was previously used in an MD array, zero the superblock:
# apt install --yes mdadm
# mdadm --zero-superblock --force /dev/disk/by-id/scsi-SATA_disk1

Clear the partition table:
# sgdisk --zap-all /dev/disk/by-id/scsi-SATA_disk1

2.2 Partition your disk:

Run this if you need legacy (BIOS) booting:
# sgdisk -a1 -n2:34:2047  -t2:EF02 /dev/disk/by-id/scsi-SATA_disk1

Run this for UEFI booting (for use now or in the future):
# sgdisk     -n3:1M:+512M -t3:EF00 /dev/disk/by-id/scsi-SATA_disk1

Choose one of the following options:

2.2a Unencrypted or eCryptfs:

# sgdisk     -n1:0:0      -t1:BF01 /dev/disk/by-id/scsi-SATA_disk1

2.2b LUKS:

# sgdisk     -n4:0:+512M  -t4:8300 /dev/disk/by-id/scsi-SATA_disk1
# sgdisk     -n1:0:0      -t1:8300 /dev/disk/by-id/scsi-SATA_disk1

Always use the long /dev/disk/by-id/* aliases with ZFS. Using the /dev/sd* device nodes directly can cause sporadic import failures, especially on systems that have more than one storage pool.

Hints:

    ls -la /dev/disk/by-id will list the aliases.
    Are you doing this in a virtual machine? If your virtual disk is missing from /dev/disk/by-id, use /dev/vda if you are using KVM with virtio; otherwise, read the troubleshooting section.

2.3 Create the root pool:

Choose one of the following options:

2.3a Unencrypted or eCryptfs:

# zpool create -o ashift=12 \
      -O atime=off -O canmount=off -O compression=lz4 -O normalization=formD \
      -O mountpoint=/ -R /mnt \
      zroot /dev/disk/by-id/scsi-SATA_disk1-part1

2.3b LUKS:

# cryptsetup luksFormat -c aes-xts-plain64 -s 256 -h sha256 \
      /dev/disk/by-id/scsi-SATA_disk1-part1
# cryptsetup luksOpen /dev/disk/by-id/scsi-SATA_disk1-part1 luks1
# zpool create -o ashift=12 \
      -O atime=off -O canmount=off -O compression=lz4 -O normalization=formD \
      -O mountpoint=/ -R /mnt \
      zroot /dev/mapper/luks1

Notes:

    The use of ashift=12 is recommended here because many drives today have 4KiB (or larger) physical sectors, even though they present 512B logical sectors. Also, a future replacement drive may have 4KiB physical sectors (in which case ashift=12 is desirable) or 4KiB logical sectors (in which case ashift=12 is required).
    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.
    Make sure to include the -part1 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).
    For LUKS, the key size chosen is 256 bits. However, XTS mode requires two keys, so the LUKS key is split in half. Thus, -s 256 means AES-128, which is the LUKS and Ubuntu default.
    Your passphrase will likely be the weakest link. Choose wisely. See section 5 of the cryptsetup FAQ for guidance.

Hints:

    The root pool does not have to be a single disk; it can have a mirror or raidz topology. In that case, repeat the partitioning commands for all the disks which will be part of the pool. Then, create the pool using zpool create ... zroot mirror /dev/disk/by-id/scsi-SATA_disk1-part1 /dev/disk/by-id/scsi-SATA_disk2-part1 (or replace mirror with raidz, raidz2, or raidz3 and list the partitions from additional disks).
    The pool name is arbitrary. On systems that can automatically install to ZFS, the root pool is named zroot by default. If you work with multiple systems, it might be wise to use hostname, hostname0, or hostname-1 instead.

Step 3: System Installation

3.1 Create a filesystem dataset to act as a container:

# zfs create -o canmount=off -o mountpoint=none zroot/ROOT

On Solaris systems, the root filesystem is cloned and the suffix is incremented for major system changes through pkg image-update or beadm. Similar functionality for APT is possible but currently unimplemented. Even without such a tool, it can still be used for manually created clones.

3.2 Create a filesystem dataset for the root filesystem of the Ubuntu system:

# zfs create -o canmount=on -o mountpoint=/ zroot/ROOT/ubuntu
# zfs mount zroot/ROOT/ubuntu

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.

3.3 Create datasets:

# zfs create                 -o setuid=off              zroot/home
# zfs create -o mountpoint=/root                        zroot/home/root
# zfs create -o canmount=on -o setuid=off  -o exec=off zroot/var
# zfs create -o com.sun:auto-snapshot=false             zroot/var/cache
# zfs create                                            zroot/var/log
# zfs create                                            zroot/var/spool
# zfs create -o com.sun:auto-snapshot=false -o exec=on  zroot/var/tmp

If you use /srv on this system:
# zfs create                                            zroot/srv

If this system will have games installed:
# zfs create                                            zroot/var/games

If this system will store local email in /var/mail:
# zfs create                                            zroot/var/mail

If this system will use NFS (locking):
# zfs create -o com.sun:auto-snapshot=false \
             -o mountpoint=/var/lib/nfs                 zroot/var/nfs

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 such as logs (in /var/log). This will be especially important if/when a beadm or similar utility is integrated. Since we are creating multiple datasets anyway, it is trivial to add some restrictions (for extra security) at the same time. The com.sun.auto-snapshot setting is used by some ZFS snapshot utilities to exclude transient data.

3.4 For LUKS installs only:

# mke2fs -t ext2 /dev/disk/by-id/scsi-SATA_disk1-part4
# mkdir /mnt/boot
# mount /dev/disk/by-id/scsi-SATA_disk1-part4 /mnt/boot

3.5 Install the minimal system:

# chmod 1777 /mnt/var/tmp
# debootstrap artful /mnt

# If /usr/sbin/debootstrap: 1454: /usr/sbin/debootstrap: cannot create /mnt/test-dev-null: Permission denied
# E: Cannot install into target '/mnt' mounted with noexec or nodev
# mount -o remount,dev,exec /mnt

# zfs set devices=off zroot

The debootstrap command leaves the new system in an unconfigured state. An alternative to using debootstrap is to copy the entirety of a working system into the new ZFS root.
Step 4: System Configuration

4.1 Configure the hostname (change HOSTNAME to the desired hostname).

# echo 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.

4.2 Configure the network interface:

Find the interface name:
# ip addr show

# vi /mnt/etc/netplan/NAME.yaml
network:
  version: 2
  ethernets:
    ens3:
      dhcp4: true

Customize this file if the system is not a DHCP client.

4.3 Configure the package sources:

# vi /mnt/etc/apt/sources.list
deb http://archive.ubuntu.com/ubuntu artful main universe
deb-src http://archive.ubuntu.com/ubuntu artful main universe

deb http://security.ubuntu.com/ubuntu artful-security main universe
deb-src http://security.ubuntu.com/ubuntu artful-security main universe

deb http://archive.ubuntu.com/ubuntu artful-updates main universe
deb-src http://archive.ubuntu.com/ubuntu artful-updates main universe

4.4 Bind the virtual filesystems from the LiveCD environment to the new system and chroot into it:

# mount --rbind /dev  /mnt/dev
# mount --rbind /proc /mnt/proc
# mount --rbind /sys  /mnt/sys
# chroot /mnt /bin/bash --login

Note: This is using --rbind, not --bind.

4.5 Configure a basic system environment:

# locale-gen en_US.UTF-8

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

# echo LANG=en_US.UTF-8 > /etc/default/locale

# dpkg-reconfigure tzdata

# ln -s /proc/self/mounts /etc/mtab
# apt update

If you prefer nano over vi, install it:
# apt install --yes nano

4.6 Install ZFS in the chroot environment for the new system:

# apt install --yes --no-install-recommends linux-image-generic
# apt install --yes zfs-initramfs

4.7 For LUKS installs only:

# echo UUID=$(blkid -s UUID -o value \
      /dev/disk/by-id/scsi-SATA_disk1-part4) \
      /boot ext2 defaults 0 2 >> /etc/fstab

# apt install --yes cryptsetup

# echo luks1 UUID=$(blkid -s UUID -o value \
      /dev/disk/by-id/scsi-SATA_disk1-part1) none \
      luks,discard,initramfs > /etc/crypttab

Notes:

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

4.8 Install GRUB

Choose one of the following options:

4.8a Install GRUB for legacy (MBR) booting

# apt install --yes grub-pc

Install GRUB to the disk(s), not the partition(s).

4.8b Install GRUB for UEFI booting

# apt install dosfstools
# mkdosfs -F 32 -n EFI /dev/disk/by-id/scsi-SATA_disk1-part3
# mkdir /boot/efi
# echo PARTUUID=$(blkid -s PARTUUID -o value \
      /dev/disk/by-id/scsi-SATA_disk1-part3) \
      /boot/efi vfat nofail,x-systemd.device-timeout=1 0 1 >> /etc/fstab
# mount /boot/efi
# apt install --yes grub-efi-amd64

4.9 Setup system groups:

# addgroup --system lpadmin
# addgroup --system sambashare

4.10 Set a root password

# passwd

4.11 Fix filesystem mount ordering

Until ZFS gains a systemd mount generator, there are races between mounting filesystems and starting certain daemons. In practice, the issues (e.g. #5754) seem to be with certain filesystems in /var, specifically /var/log and /var/tmp. Setting these to use legacy mounting, and listing them in /etc/fstab makes systemd aware that these are separate mountpoints. 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.

# zfs set mountpoint=legacy zroot/var/log
# zfs set mountpoint=legacy zroot/var/tmp
# cat >> /etc/fstab << EOF
zroot/var/log /var/log zfs defaults 0 0
zroot/var/tmp /var/tmp zfs defaults 0 0
EOF

Step 5: GRUB Installation

5.1 Verify that the ZFS root filesystem is recognized:

# grub-probe /
zfs

5.2 Refresh the initrd files:

# update-initramfs -c -k all
update-initramfs: Generating /boot/initrd.img-4.13.0-16-generic

Note: When using LUKS, this will print "WARNING could not determine root device from /etc/fstab". This is because cryptsetup does not support ZFS.

5.3 Optional (but highly recommended): Make debugging GRUB easier:

# vi /etc/default/grub
Comment out: GRUB_HIDDEN_TIMEOUT=0
Remove quiet and splash from: GRUB_CMDLINE_LINUX_DEFAULT
Uncomment: GRUB_TERMINAL=console
Save and quit.

Later, once the system has rebooted twice and you are sure everything is working, you can undo these changes, if desired.

5.4 Update the boot configuration:

# update-grub
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-4.13.0-16-generic
Found initrd image: /boot/initrd.img-4.13.0-16-generic
done

5.5 Install the boot loader

5.5a For legacy (MBR) booting, install GRUB to the MBR:

# grub-install /dev/disk/by-id/scsi-SATA_disk1
Installing for i386-pc platform.
Installation finished. No error reported.

Do not reboot the computer until you get exactly that result message. Note that you are installing GRUB to the whole disk, not a partition.

If you are creating a mirror, repeat the grub-install command for each disk in the pool.

5.5b For UEFI booting, install GRUB:

# grub-install --target=x86_64-efi --efi-directory=/boot/efi \
      --bootloader-id=ubuntu --recheck --no-floppy

5.6 Verify that the ZFS module is installed:

# ls /boot/grub/*/zfs.mod

Step 6: First Boot

6.1 Snapshot the initial installation:

# zfs snapshot zroot/ROOT/ubuntu@install

In the future, you will likely want to take snapshots before each upgrade, and remove old snapshots (including this one) at some point to save space.

6.2 Exit from the chroot environment back to the LiveCD environment:

# exit

6.3 Run these commands in the LiveCD environment to unmount all filesystems:

# mount | grep -v zfs | tac | awk '/\/mnt/ {print $3}' | xargs -i{} umount -lf {}
# zpool export zroot

6.4 Reboot:

# reboot

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

6.6 Create a user account:

Choose one of the following options:

6.6a Unencrypted or LUKS:

# zfs create zroot/home/YOURUSERNAME
# adduser YOURUSERNAME
# cp -a /etc/skel/.[!.]* /home/YOURUSERNAME
# chown -R YOURUSERNAME:YOURUSERNAME /home/YOURUSERNAME

6.6b eCryptfs:

# apt install ecryptfs-utils

# zfs create -o compression=off -o mountpoint=/home/.ecryptfs/YOURUSERNAME \
      zroot/home/temp-YOURUSERNAME
# adduser --encrypt-home YOURUSERNAME
# zfs rename zroot/home/temp-YOURUSERNAME zroot/home/YOURUSERNAME

The temporary name for the dataset is required to work-around a bug in ecryptfs-setup-private. Otherwise, it will fail with an error saying the home directory is already mounted; that check is not specific enough in the pattern it uses.

Note: Automatically mounted snapshots (i.e. the .zfs/snapshots directory) will not work through eCryptfs. You can do another eCryptfs mount manually if you need to access files in a snapshot. A script to automate the mounting should be possible, but has not yet been implemented.

6.7 Add your user account to the default set of groups for an administrator:

# usermod -a -G adm,cdrom,dip,lpadmin,plugdev,sambashare,sudo YOURUSERNAME

6.8 Mirror GRUB

If you installed to multiple disks, install GRUB on the additional disks:

6.8a For legacy (MBR) booting:

# dpkg-reconfigure grub-pc
Hit enter until you get to the device selection screen.
Select (using the space bar) all of the disks (not partitions) in your pool.

6.8b UEFI

# umount /boot/efi

For the second and subsequent disks (increment ubuntu-2 to -3, etc.):
# dd if=/dev/disk/by-id/scsi-SATA_disk1-part3 \
     of=/dev/disk/by-id/scsi-SATA_disk2-part3
# efibootmgr -c -g -d /dev/disk/by-id/scsi-SATA_disk2 \
      -p 3 -L "ubuntu-2" -l '\EFI\Ubuntu\grubx64.efi'

# mount /boot/efi

Step 7: Configure Swap

7.1 Create a volume dataset (zvol) for use as a swap device:

# zfs create -V 4G -b $(getconf PAGESIZE) -o compression=zle \
      -o logbias=throughput -o sync=always \
      -o primarycache=metadata -o secondarycache=none \
      -o com.sun:auto-snapshot=false zroot/swap

You can adjust the size (the 4G part) to your needs.

The compression algorithm is set to zle because it is the cheapest available algorithm. As this guide recommends ashift=12 (4 kiB blocks on disk), the common case of a 4 kiB page size means that no compression algorithm can reduce I/O. The exception is all-zero pages, which are dropped by ZFS; but some form of compression has to be enabled to get this behavior.

7.2 Configure the swap device:

Choose one of the following options:

7.2a Unencrypted or LUKS:

Caution: Always use long /dev/zvol aliases in configuration files. Never use a short /dev/zdX device name.

# mkswap -f /dev/zvol/zroot/swap
# echo /dev/zvol/zroot/swap none swap defaults 0 0 >> /etc/fstab

7.2b eCryptfs:

# apt install cryptsetup
# echo cryptswap1 /dev/zvol/zroot/swap /dev/urandom \
      swap,cipher=aes-xts-plain64:sha256,size=256 >> /etc/crypttab
# systemctl daemon-reload
# systemctl start systemd-cryptsetup@cryptswap1.service
# echo /dev/mapper/cryptswap1 none swap defaults 0 0 >> /etc/fstab

7.3 Enable the swap device:

# swapon -av

Step 8: Full Software Installation

8.1 Upgrade the minimal system:

# apt dist-upgrade --yes

8.2 Install a regular set of software:

Choose one of the following options:

8.2a Install a command-line environment only:

# apt install --yes ubuntu-standard

8.2b Install a full GUI environment:

# apt install --yes ubuntu-desktop

Hint: If you are installing a full GUI environment, you will likely want to manage your network with NetworkManager. In that case, delete the /mnt/etc/netplan/NAME.yaml you created.

8.3 Optional: 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

8.4 Reboot:

# reboot

Step 9: Final Cleanup

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

9.2 Optional: Delete the snapshot of the initial installation:

$ sudo zfs destroy zroot/ROOT/ubuntu@install

9.3 Optional: Disable the root password

$ sudo usermod -p '*' root

9.4 Optional:

If you prefer the graphical boot process, you can re-enable it now. If you are using LUKS, it makes the prompt look nicer.

$ sudo vi /etc/default/grub
Uncomment GRUB_HIDDEN_TIMEOUT=0
Add quiet and splash to GRUB_CMDLINE_LINUX_DEFAULT
Comment out GRUB_TERMINAL=console
Save and quit.

$ sudo update-grub

Troubleshooting
Rescuing using a Live CD

Boot the Live CD and open a terminal.

Become root and install the ZFS utilities:

$ sudo -i
# apt update
# apt install --yes zfsutils-linux

This will automatically import your pool. Export it and re-import it to get the mounts right:

# zpool export -a
# zpool import -N -R /mnt zroot
# zfs mount zroot/ROOT/ubuntu
# zfs mount -a

If needed, you can chroot into your installed environment:

# mount --rbind /dev  /mnt/dev
# mount --rbind /proc /mnt/proc
# mount --rbind /sys  /mnt/sys
# chroot /mnt /bin/bash --login

Do whatever you need to do to fix your system.

When done, cleanup:

# mount | grep -v zfs | tac | awk '/\/mnt/ {print $3}' | xargs -i{} umount -lf {}
# zpool export zroot
# reboot