Notes on Setting up BTRFS with rollbacks on Arch

notes.sh

# assumes you are using btrfs with the default subvolumes
# assumes you are using grub as your boot loader

# inotify-tools is not needed on all machines
# you can skip and check logs of grub-btrfsd after starting the 
# service and it will tell you if inotify-tools is needed
paru -S snapper snap-pac grub-btrfs snapper-rollback inotify-tools

sudo su
cd /

# snapper defaults are weird
# we need to remove the .snapshots folder to create a config
umount .snapshots
rm -r .snapshots

# create a config for root
snapper -c root create-config /
# adding -p because I am not sure if this is needed here but doesn't hurt
mkdir -p .snapshots

# no need to edit /etc/fstab since it should still be in there
# we can just remount it
mount -a

# you can safely remove the .snapshots subvolume
# since there is a subvolume called @.snapshots by default
btrfs sub delete .snapshots

# add "wheels" to group and set schedule
# https://wiki.archlinux.org/title/snapper#Set_snapshot_limits
nano /etc/snapper/configs/root

# start your engines
sudo systemctl enable --now grub-btrfsd
sudo systemctl enable --now snapper-timeline.timer
sudo systemctl enable --now snapper-cleanup.timer

# did I mention these things have weird defaults
btrfs sub set-default 256 /

# add a hook to allow changing the read only file system to write when rolling back
# this may not be necessary since there seems to be a hook you could use instead
# https://wiki.archlinux.org/title/snapper#Booting_into_read-only_snapshots
wget https://raw.githubusercontent.com/Antynea/grub-btrfs/master/initramfs/Arch%20Linux/overlay_snap_ro-install -O /etc/initcpio/install/snap-hook
wget https://raw.githubusercontent.com/Antynea/grub-btrfs/master/initramfs/Arch%20Linux/overlay_snap_ro-hook -O /etc/initcpio/hooks/snap-hook

# add "snap-hook" to the hooks
nano /etc/mkinitcpio.conf
mkinitcpio -P

# change "@snapshots" to "@.snapshots"
# uncomment and set your root device id on the last line
nano /etc/snapper-rollback.conf

mount -a

# to help preserve my SSD lifespan there are a few additional things I did
#   1. enabled compression on all btrfs mounts in /etc/fstab with "compress=zstd" (the default level 3 is good)
#   2. I added subvolumes `/var/cache`, `/var/lib/docker`, `/var/lib/flatpak`. Since those folders would bloat up my rollback root snapshots
#      I used a script to allow me to create subvolumes for busy folders here:
#      https://gist.github.com/zatricky/b195b474ed5f3c3c4c57e878eef4f0f5
#      Make sure to add the new subvolume to /etc/fstab e.g. ... subvol=/@/var/cache
#   3. edit /usr/lib/systemd/system/snapper-timeline.timer to weekly so less snapshots need to be made