Arch Linux + snapshots + KDE Plasma test on VM

🔎 Description

Instructions for installing and configuring a Linux system based on Arch Linux with snapshot functionality. System uses required BTRFS partitions, Snapper for snapshots and KDE Plasma desktop. This setup is used for testing on a VM machine. These instructions are based on arch wiki and installanion guide. All was tested with Qemu virtual manager and archlinux-2024.11.01 ISO.

The goal is to have a "bleeding edge" system as the main home desktop environment, and to be able to have the latest packages for testing, while being backed up by snapshots and able to quickly restore the system after failed updates, upgrades or critical changes.

✍🏼Collaboration

This is my discovery attempt to create such a system setup. Please contact me or create an issue if you have better suggestions or find bugs.

✨ Features

Create and restore system snapshots using Snapper
BTRFS system partition - required for system snapshots
Create automatic snapshots before and after system and software updates with snap-pac
Restore the system from the boot menu with grub-btrfs
Desktop Environment - KDE Plasma

🛠️ Installation setup

SSH connection

If the device and VM are connected to the same Internet, which is usually the case with Virtual Manager installed on the local computer, it is easy to connect via SSH and use the local computer's terminal to install Arch. This is a more convenient option. It is easier to change the font size, scroll through the terminal window to see older commands and output.

First install ssh on the VM Arch installation, enable the ssh service and set the ISO root password for security.

pacman -Sy --needed openssh;
systemctl enable sshd;
passwd

Check IP address on the VM to connect on local machine

ip address

Now connect via ssh on your local machine

ssh root@<your_ip_address>

Setting up the keyboard layout

Use the grep command to find your keyboard layout typing your language code

localectl list-keymaps | grep <your_language_code>

Apply keyboard settings with command

loadkeys <language_code>

Connect to the Internet

This step is not required in the VM, this should just work as machine connected through the Ethernet cable.

To connect to WiFi:

iwctl

And use steps: device list -> station <device> scan -> station <device> get-networks -> station <device> connect <Network_name> -> exit.

Update the system clock

Clock should be synced automatically. To check the status of the system clock run:

timedatectl

💾 Partitioning

First if you are not sure you can check what type of boot mode is in your system. Run below command. If the file exists you are on UEFI, if not you are on BIOS.

cat /sys/firmware/efi/fw_platform_size

Creating and formatting partitions

The easiest way to partition the hard disk is to use cfdisk. VM is probably using BIOS, so here won't be any instructions on how to create a UEFI partition in this guide (for now). Create two partitions, one for BIOS, 100MB is more than enough, and the rest for the Linux filesystem.

cfdisk /dev/<disk>

Format the Linux partition as BTRFS and add a larger node size for metadata (default 16k max 64k). Higher node sizes give better packing and less fragmentation at the cost of more expensive memory operations while updating the metadata blocks.

mkfs.btrfs -f -L <your_label> -n 32k /dev/<linux_partition>

Creating subvolumes

⚠️ - The only way to add new subvolumes later after this installation is to go into recovery mode and repeat the following steps as root. It is necessary to remount partition to the /mnt like below. Another option is to use the live ISO.

Mount the Linux partition:

mount /dev/<linux_patrition> /mnt

Create BTRFS subvolumes, the su cr command is an abbreviation of subvolume create. The following subvolumes are required for snapper and the system to work properly. @pacman and @tmp are to reduce snapshot creations slowdowns.

btrfs su cr /mnt/@;
btrfs su cr /mnt/@home;
btrfs su cr /mnt/@snapshots;
btrfs su cr /mnt/@log;
btrfs su cr /mnt/@pacman;
btrfs su cr /mnt/@tmp;
btrfs su cr /mnt/@swap

Now unmount /mnt and remount the Linux partition with below settings

umount /mnt;
mount -o noatime,compress=lzo,space_cache=v2,subvol=@ /dev/<linux_patrition> /mnt

More about selected options can be found here: link.

Option	desc
noatime	Significantly improves performance because no new access time information needs to be written. Default option here is `relatime`, but it is not working well with BTRFS! Read more in here
compress	Control BTRFS file data compression. Type may be specified as zlib, lzo, zstd or no. More in here: link
space_cache	The free space cache greatly improves performance when reading block group free space into memory. V2 is newer better version. But it is good to make sure to have it is set.
subvol	Subvolume path

Create folders for home, snapshots, swap and other subvolumes...

mkdir -p /mnt/{home,var/log,var/tmp,var/cache/pacman/pkg,.snapshots,swap}

...and mount subvolumes

mount -o noatime,compress=lzo,space_cache=v2,subvol=@home /dev/<linux_partition> /mnt/home;
mount -o noatime,compress=lzo,space_cache=v2,subvol=@log /dev/<linux_partition> /mnt/var/log;
mount -o noatime,compress=lzo,space_cache=v2,subvol=@tmp /dev/<linux_partition> /mnt/var/tmp;
mount -o noatime,compress=lzo,space_cache=v2,subvol=@pacman /dev/<linux_partition> /mnt/var/cache/pacman/pkg;
mount -o noatime,compress=lzo,space_cache=v2,subvol=@snapshots /dev/<linux_partition> /mnt/.snapshots

💿 System installation

Setting up mirrors for faster downloads

This can speed up download time and help to prevent timeouts. Example below shows command to select the HTTPS mirrors that have been synchronised within the last 12 hours and are located in either Country1 and Country2, sort them by download speed, and overwrite the /etc/pacman.d/mirrorlist file with the results.

reflector --country <Country1>,<Country2> --protocol https --age 12 --sort rate --save /etc/pacman.d/mirrorlist

Install base system and libraries

Here we are installing latest linux kernel and other packages for system to work. To install LTS linux change linux to linux-lts and linux-lts-headers or have them both. In this step I am adding also snapper and grub-btrfs.

pacstrap -K /mnt base base-devel btrfs-progs git grub grub-btrfs inotify-tools linux linux-firmware linux-headers man neovim networkmanager openssh reflector snapper sudo

Generate `fstab` file

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

⌨️ Chroot and final setup

arch-chroot /mnt

Set the date and time

To find your time zone run:

timedatectl list-timezones | grep <country>

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

Set the hardware clock with command:

hwclock --systohc

Set locale

Uncomment your locale in /etc/locale.gen and save the changes. Generate the locale and add a new line with your locale to /etc/locale.conf.

locale-gen;
echo LANG=<locale> > /etc/locale.conf

Set up your keymap settings.

echo "KEYMAP=<keymap>" > /etc/vconsole.conf

Set hostname and hosts

my_hostname=<hostname>;
echo $my_hostname >> /etc/hostname;
echo "127.0.0.1   localhost"$'\n'"127.0.1.1   $my_hostname.localdomain $my_hostname"$'\n'"::1         localhost" >> /etc/hosts

Set root password and create user

my_username=<username>;
passwd;
useradd -m -g users -G wheel $my_username;
passwd $my_username

Use the following command and uncomment the line %wheel ALL=(ALL) ALL line to enable sudo:

EDITOR=nvim visudo

Enable network manager and ssh services

systemctl enable NetworkManager;
systemctl enable sshd

Create and enable swapfile

⚠️ - Swapfile needs to be mounted as subvolume, otherwise Snapper won't work. There can be error like Cannot create snapshot.

Instructions how to enable swap on BTRFS are here: link. I found it easier to make swap work with snapshots and BTRFS by creating swapfile manually rather than using the above instructions form the Arch wiki. First, mount the @swap subvolume, create a swapfile inside the swap folder and give it 600 permissions. Use the chattr command to disable copy on write for this file. Set the size of the swap with the dd command where: if - input file, of - output, bs - block size and count is swap size. After that format swapfile and turn on swap.

⚠️ - Use dd to allocate swap space instead of fallocate, because it can create file-system holes, more info here.

swap_size=2048;
sudo mount -o subvol=@swap /dev/<linux_partition> /swap;
sudo touch /swap/swapfile;
sudo chmod 600 /swap/swapfile;
sudo chattr +C /swap/swapfile;
sudo dd if=/dev/zero of=/swap/swapfile bs=1024 count=$swap_size;
sudo mkswap /swap/swapfile;
sudo swapon /swap/swapfile

Edit fstab and add swapfile entries at the end of the file to make changes permanent. First defines that /swap folder is a separate subvolume and second defines swapfile.

echo 'UUID=<uudi_of_the_btrfs>  /swap  btrfs  subvol=/@swap  0  0' >> /etc/fstab;
echo '/swap/swapfile            none   swap   defaults       0  0' >> /etc/fstab

Verify the /etc/fstab file after all changes. SWAP should work now with correctly together with snapshots.

Installing and configuring the GRUB boot loader

⚠️ - Here give the path to your hard disk, not the partition volume where you want to install GRUB, e.g. instead of vda2 use vda.

grub-install /dev/<disk>;
grub-mkconfig -o /boot/grub/grub.cfg;
exit

Unmount /mnt and reboot the system to finish the installation.

umount -R /mnt;
reboot

Snapper configuration

To list your BTRFS subvolumes use command:

sudo btrfs sub list /

These steps are described on the Arch wiki page here. To run snapper configuration first unmount snapshots volume and remove snapshots folder created before or make sure it is not there.

sudo umount /.snapshots;
sudo rm -r /.snapshots;
sudo snapper -c root create-config /

Above command creates another subvolume /.snapshots that we do not need. Delete this subvolume, create subvolume folder if not exists and mount subvolume:

sudo btrfs sub del /.snapshots/;
sudo mkdir /.snapshots;
sudo mount -o subvol=@snapshots /dev/<linux_filesystem> /.snapshots

Verify if snapshots subvolume is now in /etc/fstab. Mount all subvolumes and give 750 permissions to .snapshots folder

sudo mount -a;
sudo chmod 750 /.snapshots

Snapper setup

Configuration files for Snapper are in /etc/snapper/configs/root file. To use it as a sudo user there is need to add user and group to configuration file.

sudo nvim /etc/snapper/configs/root

Add user and group to be able to use Snapper as user not root:

ALLOW_USERS="my_username"
ALLOW_GROUPS="wheel"

By default Snapper is creating scheduled hourly snapshots. This is not working until we not install and enable cronie:

sudo pacman -S --needed cronie;
sudo systemctl enable cronie.service

If you do not want cronie you can use enable below (optional):

sudo systemctl enable --now snapper-timeline.timer
sudo systemctl enable --now snapper-cleanup.timer

If you do not want to schedule snapshots hourly, this can be disabled by setting below to no:

TIMELINE_CREATE="no"

If above option is set to yes, Snapper is keeping 10 hourly, daily, monthly and yearly snapshots. This can be limited in options e.g. like so:

TIMELINE_MIN_AGE="1800"
TIMELINE_LIMIT_HOURLY="5"
TIMELINE_LIMIT_DAILY="7"
TIMELINE_LIMIT_WEEKLY="0"
TIMELINE_LIMIT_MONTHLY="3"
TIMELINE_LIMIT_YEARLY="5"

To manually create snapshots use command with the description use:

snapper create --description "my_snapshot_name"

Restore snapshots from GRUB menu

To enable snapshot restoration from GRUB install grub-btrfs package (done in previous steps). More info about Snapper configuration here: grub-btrfs.

To manually generate GRUB snapshot entries you can run:

sudo /etc/grub.d/41_snapshots-btrfs

To enable auto refresh list of snapshots in GRUB menu enable grub-btrfsd service:

sudo systemctl enable grub-btrfsd

Update GRUB to apply all changes.

sudo grub-mkconfig -o /boot/grub/grub.cfg

Fix restore read only snapshots from GRUB

There can be error about restoring read only snapshots on system boot from GRUB menu. Instructions to fix this for Arch are here: https://github.com/Antynea/grub-btrfs/blob/master/initramfs/readme.md .

git clone https://github.com/Antynea/grub-btrfs.git;
sudo cp grub-btrfs/initramfs/Arch\ Linux/overlay_snap_ro-install /etc/initcpio/install/grub-btrfs-overlayfs;
sudo cp grub-btrfs/initramfs/Arch\ Linux/overlay_snap_ro-hook /etc/initcpio/hooks/grub-btrfs-overlayfs;
rm -rdf grub-btrfs

Next edit /etc/mkinitcpio.conf file and add grub-btrfs-overlayfs at the end of the line HOOKS=(... grub-btrfs-overlayfs).

sudo nvim /etc/mkinitcpio.conf

Regenerate mkinitcpio

sudo mkinitcpio -P

Auto create snapshots before and after running Pacman

Bleeding edge system can crash during updates. It is very handy to automatically create snapshot before installing updates. For more details check: snap-pac.

sudo pacman -S snap-pac

⚙️ Post installation steps

Log in to the system using the credentials provided in the installation steps. If you need to connect to the WiFi, you can use: nmtui.

Install desktop environment

Install CPU driver, sound driver, printers, etc

sudo pacman -S cups hplip intel-ucode pipewire pipewire-alsa pipewire-pulse pipewire-jack wireplumber;
sudo systemctl enable cups

Install KDE Plasma and kscreen for screen management.

sudo pacman -S plasma-desktop kscreen

Install browser and terminal

sudo pacman -S firefox kitty

Install graphic card drivers for Intel dedicated graphics

sudo pacman -S xf86-video-intel

Install SDDM

Display managers are useful if you have multiple DE's or WM's and want to choose where to boot from in a GUI fashion They also they take care of the launch process.

sudo pacman -S sddm

Enable SDDM service to make it start on boot.

sudo systemctl enable sddm

For KDE install this to control the SDDM configuration from the KDE settings App.

sudo pacman -S --needed sddm-kcm

Name		Name	Last commit message	Last commit date
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CHANGELOG.md		CHANGELOG.md
LICENSE		LICENSE
README.md		README.md
my_setup.sh		my_setup.sh

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MateuszMielniczuk/arch-linux-snapshots

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