Arch Linux - Btrfs Installation (Dual Boot)

Arch Linux installation with btrfs filesystem dual booting with Windows.

Abstract

So I want to show you how to install Arch Linux with btrfs dual booting with Windows. You can read about Arch here: Arch Wiki - Arch Linux.

Prerequisite

• A USB drive for Arch ISO (8 GB recommended)
• Arch ISO (Get it here)
• x86_64 device
• UEFI
• Minimum 512 MB of RAM (more than 2 GB recommended)
• 20-30 GB free disk space (60 GB upwards recommended)
• Internet connection

Installation Process

Even tho I'll show you how-to, Arch Wiki itself has substantial informations regarding the installation. Be sure to check out the official wiki for reference while also following this guide: Arch Wiki - Installation Guide.

Preparing installation medium

At this step, I assume you already have the Arch ISO and know how to burn ISO files to USB. Now, burn the ISO to your USB using Etcher, Rufus, or any tools that you like. I recommend Ventoy as you only need to copy the ISO to your flashdisk.

Make sure to shrink your Windows partition and then create 3 empty partitions from Windows Partition Manager (or something like that idk) consisting of:

• 512 MB empty partition (EFI partition)
• 20-30 GB or more empty partition (root partition)
• 4 GB or more empty partition (Swap partition)

Keymapping (Optional)

Note: If you use standard QWERTY layout, skip this step.

Check the list of keymaps available using:

localectl list-keymaps

Then set your preferred keymap by using:

loadkeys [your-keymap]

Connecting to the internet

Arch uses iwctl for connecting to the internet via Wifi. If you're using USB tethering or Ethernet, skip this step.
Run iwctl by issuing:

iwctl

First, if you do not know your wireless device name, list all Wi-Fi devices:

[iwd]# device list

Then, to scan for networks:

[iwd]# station _device_ scan

You can then list all available networks:

[iwd]# station _device_ get-networks

Finally, to connect to a network:

[iwd]# station _device_ connect _SSID_

You can check your network by just:

ping 8.8.8.8 -c 3

Set time

Use timedatectl to ensure the system clock is accurate:

timedatectl set-ntp true

Partitioning

Since we've already created 3 partitions in Windows, we can just jump on to formatting the partitions. But first, you must check which partitions are going to be used.
The command is:

fdisk -l

For example, my layout looks like this:

• /dev/nvme0n1p6 | 512 MB => This is going to be the EFI partition.
• /dev/nvme0n1p7 | 4 GB => This will be the swap partition.
• /dev/nvme0n1p8 | 71.7 GB => This is going to be the root partition.

Yours might look different, but the concept is the same.
Then we format our partitions using mkfs and mkswap.

For the EFI boot entry:

mkfs.fat -F32 /dev/nvme0n1p6

For the swap partition, we need to make and also activate it:

mkswap /dev/nvme0n1p7
swapon /dev/nvme0n1p7

For the root partition, we need to format it as btrfs:

mkfs.btrfs /dev/nvme0n1p8

Mounting the partitions

Now that we have formatted the partitions, we need to mount it (exception for swap).

Mounting the root partition

To mount the root partition, issue the command:

mount /dev/nvme0n1p8 /mnt

Creating and mounting btrfs subvolumes

Since we've mounted the root partition, we can proceed into creating btrfs subvolumes.
We'll create 6 different subvolumes:

• @ => root directory.
• @home => home directory. Contains all your personal data.
• @var => var directory. Contains logs, etc.
• @opt => opt directory. Contains third party products.
• @tmp => tmp directory. Contains temp files, etc.
• @.snapshot => snapshot directory. Contains btrfs snapshots. (Can be excluded if you want to use Timeshift)

Create the subvolumes:

btrfs su cr /mnt/@
btrfs su cr /mnt/@home
btrfs su cr /mnt/@var
btrfs su cr /mnt/@opt
btrfs su cr /mnt/@tmp
btrfs su cr /mnt/@.snapshots
umount /mnt

Now to mount them:

mount -o noatime,commit=120,compress-force=zstd:7,discard=async,space_cache,subvol=@ /dev/nvme0n1p8 /mnt
mkdir /mnt/{boot,home,var,opt,tmp,.snapshots} # You must create the folders before proceeding
mount -o noatime,commit=120,compress-force=zstd:7,discard=async,space_cache,subvol=@home /dev/nvme0n1p8 /mnt/home
mount -o noatime,commit=120,compress-force=zstd:7,discard=async,space_cache,subvol=@tmp /dev/nvme0n1p8 /mnt/tmp
mount -o noatime,commit=120,compress-force=zstd:7,discard=async,space_cache,subvol=@opt /dev/nvme0n1p8 /mnt/opt
mount -o noatime,commit=120,compress-force=zstd:7,discard=async,space_cache,subvol=@.snapshots /dev/nvme0n1p8 /mnt/.snapshots
mount -o discard=async,subvol=@var /dev/nvme0n1p8 /mnt/var

A little review about the options:

• noatime: No access time. Improves performance by not writing time when the file was accessed.
• commit: Perodic interval (in seconds) in which data is synchronized to permanent storage.
• compress-force: Activating forced compression and choosing the algorithm for compression. (Believe me, this is good, no joke)
• discard=async: Frees unused block from an SSD drive supporting the command. With discard=async, freed extents are not discarded immediately, but grouped together and trimmed later by a separate worker thread, improving commit latency. You can opt out of this if you use HDD.
• space_cache: Enables kernel to know where block of free space is on a disk to enable it to write data immediately after file creation.
• subvol: Choosing the subvolume to mount.

Mounting the EFI (boot) partition

To mount it, just issue:

mount /dev/nvme0n1p6 /mnt/boot

Verify if you are doing it correctly

To check what is being mounted, issue:

lsblk

Base system installation

For AMD CPUs:

pacstrap /mnt base linux linux-firmware nano amd-ucode btrfs-progs

For Intel CPUs:

pacstrap /mnt base linux linux-firmware nano intel-ucode btrfs-progs

Generating fstab

After the base system installation is done, now we need to generate the fstab to define what and how partitions should be mounted.
Generate it by issuing:

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

Verify it by issuing:

cat /mnt/etc/fstab

Chroot into the root partition

Now enter your Arch install:

arch-chroot /mnt

Setting up timezone

Before you set up timezone, you might want to check which timezones are available by issuing:

timedatectl list-timezones

Press 'q' to quit the list.

Now set up your timezone by using:

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

Sync hardware and system clock

Issue this command:

hwclock --systohc

Generating system locale

Issue this command to edit the locale.gen:

nano /etc/locale.gen

Scroll and uncomment your language. Most people would prefer US English so scroll down and uncomment this line:

en_US.UTF-8 UTF8

Save the file by using CTRL + S and exit it with CTRL + X.

Now generate locale:

locale-gen

Set the locale in locale.conf file:

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

Change en_US.UTF-8 to your preferred language (if true).

Setting keymap

Note: This is only if you use keymaps other than the standard QWERTY.

echo KEYMAP=[keymap] >> /etc/vconsole.conf

Replace [keymap] with the ones you choose before.

Setting network configuration

Set your hostname with:

echo example >> /etc/hostname

Replace the example with anything you want.

Now for the hostfile:

nano /etc/hosts

Reffering to Arch Wiki, the format should look like this:

127.0.0.1   localhost
::1         localhost
127.0.1.1   example.localdomain example

Save the file by using CTRL + S and exit it with CTRL + X.

Setting up the root user

Set up password for the root user with:

passwd

Note: Visual feedbacks are disabled by default in Linux because of security reasons.

Installing remaining essentials

pacman -S grub grub-btrfs efibootmgr base-devel linux-headers networkmanager network-manager-applet wpa_supplicant dialog os-prober mtools dosfstools reflector git

These are some basic sets of packages you will need if you plan to use Arch in the long run. I would recommend that you google all packages to understand what they do. After entering the command, press Enter to select all of the base-devel packages to install. Then wait for the installation to finish.

Modifying mkinitcpio

nano /etc/mkinitcpio.conf

Add btrfs into MODULES so that it looks like:

...
MODULES=(btrfs)
...

Save the file by using CTRL + S and exit it with CTRL + X.

Installing GRUB

To install GRUB into the /boot partition, issue these commands:

grub-install --target=x86_64-efi --efi-directory=/boot --bootloader-id=Arch
grub-mkconfig -o /boot/grub/grub.cfg

Creating a user

Issue this command to create a new user:

useradd -mG wheel example

Above command creates a user with name example and adds the user to the wheel group (for sudo privileges). Replace example with whatever name you want.

Then create the password for the user:

passwd example

Giving user sudo permission

EDITOR=nano visudo

Uncomment the line %wheel ALL=(ALL) ALL

Enabling NetworkManager

systemctl enable NetworkManager.service

Finishing and restarting

Issue these commands to finish installation:

exit
umount -l /mnt
reboot

Post Installation

Ah yes, the pain is gone ultimately. You've installed Arch Linux successfully! Go ahead and install some DE or WM on top.

For some post install recommendations:
Arch Wiki - General Recommendations

As always, thank you for your time!

References

• https://www.nishantnadkarni.tech/posts/arch_installation/ - Arch Linux with BTRFS Installation (Base) - NishantN
• https://wiki.archlinux.org/title/Installation_guide - Installation Guide - Arch Wiki
• https://wiki.archlinux.org/title/btrfs - Btrfs - Arch Wiki
• https://wiki.archlinux.org/title/Iwd#iwctl - Iwd/iwctl - Arch Wiki