ZFS

Preamble

ZFS Primer

ZFS Schema

Basic Strategy

ZFS is not included in the linux kernel due to licensing. So the solution is to add the zfs kernel modules and zfs utilities to the base arch linux installation. These are maintained in the archzfs repo. This can be done by creating a custom .iso or by a script from eoli3n with a standard .iso - which is easier. Use the OpenZFS for Arch Linux as a guide.
The next steps are to create the zfs pool and datasets. The main difference here is the pool and datasets will try to automount on creation so the -o mountpoint=none or -o mountpoint=noauto is used to prevent issues. Then just install arch linux as per normal, remembering that on the new installation the archzfs repo and the archzfs-linux package need to be installed again.
For booting, I decided to go with zfsbootmenu - basically an .efi app that can boot from a kernel + initramfs pair found in /boot on any zfs dataset. zfsbootmenu also works nicely with rEFINd.

Starting Out

Using the archzfs script (preferred)

curl -s https://eoli3n.github.io/archzfs/init | bash

Run this after booting standard .iso - it will load zfs kernel modules and utilities to allow making zpool etc. To make sure no errors run modprobe zfs

2. Making a custom archiso (optional)

Need zfs kernel modules and zfs utils from the archzfs repoi. archzfs is not always up to date with latest kernal so check on https://archzfs.com/archzfs/x86_64.
Add keys and edit pacman.conf to include the archzfs repo. Then add linux-headers and archzfs-linux to the package list (these are the kernel modules and zfs utilites).
Use the arch archive how to determine dates for pacman - match to date of most recent archzfs. Then run mkarchiso -v

Installation

Partitioning

sgdisk/gdisk which are interactive/transactional but do the same thing

sgdisk --zap-all /dev/disk/by-id/<disk0>

sgdisk -n1:0:+512M -t1:ef00 /dev/disk/by-id/<disk0>

sgdisk -n2:0:+210G -t2:bf00 /dev/disk/by-id/<disk0>

### sgdisk -n2:0:+8G -t2:8200 /dev/disk/by-id/<disk0>

### Not using a swap parition but could consider ZRAM in future ?

### The EFI partition will just be for EFI applications and will be mounted to /boot/efi - the kernel will be in /boot

mkfs.vfat /dev/xxx1

I have also created another zpool: bakpool with data set archzfs on a seperate internal ssd to test stuff. This should mount at /mnt/backpool/archzfs

Create the zpool

zpool create -f -o ashift=12 \

-O acltype=posixacl \

-O relatime=on \

-O xattr=sa \

-O dnodesize=legacy \

-O normalization=formD \

-O mountpoint=none \

-O canmount=off

-O compression=lz4 \

-O devices=off \

-R /mnt \

zroot /dev/disk/by-id/id-to-partition-partx

\### Use the /dev/disk/by-id/id for this found by ls /dev/disk/by-id/

Create the datasets

zfs create -o canmount=off -o mountpoint=none rpool/ROOT

zfs create -o mountpoint=/ -o canmount=noauto rpool/ROOT/default

zfs create -o mountpoint=none rpool/DATA

zfs create -o mountpoint=/home rpool/DATA/home

zfs create -o mountpoint=/root rpool/DATA/home/root

zfs create -o mountpoint=/local rpool/DATA/local

zfs create -o mountpoint=none rpool/DATA/var

zfs create -o mountpoint=/var/log rpool/DATA/var/log # after a rollback, systemd-journal blocks at reboot without this dataset

\### give the dataset you want to boot from a boot flag

zpool set bootfs=rpool/ROOT/default rpool

Sanity check zpool before proceeding

\### If no errors then able to proceed to install arch in zpool

zfs umount -a

rm -rf /mnt/*

zpool export rpool

zpool import -d /dev/disk/by-id -R /mnt rpool -N

\### The root pool should be mounted first, then the rest

zfs mount rpool/ROOT/default /mnt

zfs mount -a

\### Mount the EFI partition to /boot/efi (NOT to /boot)

mkdir /mnt/boot/efi

mount /dev/xxx1 /mnt/boot/efi

Prepare the new system

mkdir /mnt/etc

genfstab -U /mnt >> /mnt/etc/fstab

pacstrap /mnt base base-devel linux linux-firmware vim

arch-chroot /mnt

In chroot

Remove all lines in /etc/fstab leaving just efi partition mount to /boot/efi

\### add the archzfs repor to /etc/pacman.conf

[archzfs]

Server = http://archzfs.com/$repo/x86_64

\### Add GPG Keys

curl -O https://archzfs.com/archzfs.gpg

pacman-key -a archzfs.gpg

pacman-key --lsign-key DDF7DB817396A49B2A2723F7403BD972F75D9D76

pacman -Syy

\### Timezone

ln -sf /usr/share/zoneinfo/Region/City /etc/localtime

hwclock --systohc

\### Generate locale

sed -i 's/#$en_US\.UTF-8$/\1/' /etc/locale.gen

locale-gen

echo "LANG=en_US.UTF-8" > /etc/locale.conf

\### Set root password

passwd

\### Install important stuff, esp. archzfs-linux!!!

pacman -Syu archzfs-linux amd-ucode sudo openssh git neovim

\### Generate hostid

zgenidhost $(hostid)

\### Generate cache file - Important!

zfs set cachefile=/etc/zfs/zpool.cache zroot

\### edit /etc/mkinitcpio.conf and make sure zfs is added

HOOKS=(base udev autodetect modconf block keyboard zfs filesystems)

\##**regenerate**{: .hash} initramfs

mkinitcpio -p linux

Enable services

\### ZFS specific services

systemctl enable zfs.target

systemctl enable zfs-import-cache

systemctl enable zfs-mount

systemctl enable zfs-import.target

\### create an entry for wired ethernet in /etc/systemd/network/20-wired.network

[Match]

Name=enp6s0

[Network]

DHCP=yes

\### Network and other services

systemctl enable systemd-networkd

systemctl enable systemd-resolved

systemctl enable sshd

Create a user

useradd -m -G wheel,adm -s /bin/bash username

\### -m creates /home/username but need to change permissions

chown -R username:group /home/username && chmod 700 /home/username

passwd username

EDITOR=vim visudo

\### uncommment wheel line

\### su and install paru as a normal user

sudo pacman -S --needed base-devel

git clone https://aur.archlinux.org/paru.git

cd paru

makepkg -si

Bootloader

Switch back to root - su and see # prompt

Mount your ESP to /boot/efi

Install zfsbootmenuAUR and efibootmgr

Configure ZFSBootMenu

\### /etc/zfsbootmenu/config.yaml

Global:

ManageImages: true

BootMountPoint: path_to_your_ESP

DracutConfDir: /etc/zfsbootmenu/dracut.conf.d

PreHooksDir: /etc/zfsbootmenu/generate-zbm.pre.d

PostHooksDir: /etc/zfsbootmenu/generate-zbm.post.d

InitCPIO: true

InitCPIOConfig: /etc/zfsbootmenu/mkinitcpio.conf

Components:

ImageDir: path_to_your_ESP/EFI/zbm

Versions: 3

Enabled: false

syslinux:

Config: /boot/syslinux/syslinux.cfg

Enabled: false

EFI:

ImageDir: path_to_your_ESP/EFI/zbm

Versions: false

Enabled: true

Kernel:

CommandLine: ro quiet loglevel=0

Generate a ZFSBootMenu image

generate-zbm

Configure zfs boot commandline arguments

zfs set org.zfsbootmenu:commandline="rw" zroot/ROOT/default

Add a ZFSBootMenu entry to EFI boot manager

efibootmgr -c -d your_esp_disk -p your_esp_partition_number -L "ZFSBootMenu" -l '\EFI\zbm\vmlinuz-linux.EFI'

Exit and reboot

exit

zfs umount -a

umount -R /mnt

zpool export rpool

\### cross fingers and reboot

reboot