Arch installation on a BTRFS root filesystem

This is a cheatsheet with all the instructions to perform an installation of Arch Linux using BTRFS filesystem in /

Please, read the entire document before proceeding because it includes two different approaches. The key is to include /boot directory in the snapshots for root in order to be able to rollback the entire system without any problem it it is needed. Lets proceed!

[TOC]

Laptop model

The installation has been done on a Mountain Onyx laptop.

• Screen: 15,6" Full HD IPS Mate
• CPU: Intel® Core™ i7 6700HQ - 4C/8T
• RAM: 8GB DDR3L 1600 SODIMM
• Hard Disk: SSD 240GB M.2 550MB/s
• GPU: Nvidia GTX 960M 2GB GDDR5 + Intel i915 (Skylake)
• UEFI

Approach 1 [UEFI, GPT and GRUB]

I have been following Official Arch Installation Guide. Arch ISO booted in UEFI mode using systemd-boot. It was configured a wired connection too.

Partitioning

This is the selected layout for the UEFI/GPT system:

Mount point	Partition	Partition type	FS Type	Bootable flag	Size
/boot/efi	/dev/sda1	EFI System Partition	FAT32	Yes	512 MiB
[SWAP]	/dev/sda2	Linux swap	SWAP	No	16 GiB
/	/dev/sda3	Linux	BTRFS	No	222 GiB

After creating the partitions using fdisk, it was necessary to format them. Again, I followed the guide without a problem.

IMPORTANT: I used -L option with mkfs command in order to create a label for / (called arch).

BTRFS layout

The only partition formated with BTRFS was /dev/sda3, which contains the whole root system. BTRFS was selected to enable snapshots support in order to avoid any possible problem with Arch updates. Sometimes, I have experimented that certain critical package updates can break the system. If it occurs, it is a good idea to have some snapshot to rollback the entire root filesystem. tmp snapshots never will be created, because all the files stored within tmp are temporal. This is the layout defined:

sda3 (Volume)
|
|
- _active (Subvolume)
|    |
|    - rootvol (Subvolume - It will be the current /)
|    - homevol (Subvolume - it will be the current /home)
|
- _snapshots (Subvolume -  It will contain all the snapshots which are subvolumes too)

And these are the commands:

mkfs.btrfs -L arch /dev/sda3
mount /dev/sda3 /mnt
cd /mnt
btrfs subvolume create _active
btrfs subvolume create _active/rootvol
btrfs subvolume create _active/homevol
btrfs subvolume create _snapshots

Next, create all the directories needed and mount all the partitions (/boot/efi included) in order to start the installation:

cd ..
umount /mnt
mount -o subvol=_active/rootvol /dev/sda3 /mnt
mkdir /mnt/{home,boot}
mkdir /mnt/boot/efi
mkdir /mnt/mnt/defvol
mount /dev/sda1 /mnt/boot/efi
mount -o subvol=_active/homevol /dev/sda3 /mnt/home
mount -o subvol=/ /dev/sda3 /mnt/mnt/defvol

Installing Arch Linux

Proceed with the installation according to the official guide.

Fstab

After executing genfstab -U /mnt >> /mnt/etc/fstab to generate fstab file using UUIDs for the partitions, I edited fstab in order to remove completely subvolids for example (they are not needed and it makes rollback much more easy) and adding compression to BTRFS mounted points and this is the result. Please, be aware of /mnt/defvol mounting point. This directory is very important because the WHOLE BTRFS volume will be mounted here and you will have access to all subvolumes and snapshots created after the installation)

# /dev/sda3 LABEL=arch
UUID=9882a07e-0a0c-419d-bbdd-cbfbc4a6ffc9       /               btrfs           rw,relatime,compress=lzo,ssd,discard,autodefrag,space_cache,subvol=/_active/rootvol     0 0

# /dev/sda1
UUID=3074-C66B          /boot/efi       vfat            rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro       0 2

# /dev/sda3 LABEL=arch
UUID=9882a07e-0a0c-419d-bbdd-cbfbc4a6ffc9       /home           btrfs           rw,relatime,compress=lzo,ssd,discard,autodefrag,space_cache,subvol=_active/homevol     0 0

# /dev/sda2
UUID=9943adc7-d8a5-4500-bb35-3179aca961f5       none            swap            defaults        0 0

UUID=9882a07e-0a0c-419d-bbdd-cbfbc4a6ffc9       /mnt/defvol     btrfs           rw,relatime,compress=lzo,ssd,discard,autodefrag,space_cache,subvol=/        0 0

Mkinitcpio

In order to enable BTRFS on initramfs image, I added btrfs on HOOK inside /etc/mkinitcpio.conf. Then, it was necessary to execute mkinitcpio -p linux again. If you install linux-lts kernel (Long Term Support), you will have to execute mkinitcpio -p linux-lts

Microcode

I installed intel-ucode package because I have an Intel CPU.

Bootloader

If you want to have BTRFS snapshots integrated from booting you will have to install GRUB. Thanks to grub-btrfs package, you will be able to boot your system directly from any snapshot of ROOT created. All these snapshots will be populated in the GRUB menu.

GRUB is totally compatible with EFI systems. Install grub and efibootmgr:

pacman -S grub efibootmgr

Install the GRUB EFI application executing this command (please, choose the directory where EFI application will be stored, in my case /boot/efi, the partition created before):

grub-install --target=x86_64-efi --efi-directory=/boot/efi --bootloader-id=GRUB

Generate the main grub.cfg configuration file:

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

Additional packages installed

A bunch of useful packages has been installed too: tlp for energy saving and advanced power management, reflector for optimizing Arch mirrors repositories, yay for compiling and installing packages easily from AUR repository, snapd to install snap packages, btrfs-progs to manage BTRFS filesystem.

Finish the steps in the Wiki

And reboot!!

Automated snapshots and system updates

Recently I have developed a graphical tool for creating BTRFS snapshots, balancing filesystems and upgrading the system safetly. It works in Arch Linux and Debian, Ubuntu or derivatives. For more information, please check ButterManager. Please, read the documentation in order to configure it before the first use.

If you prefer another option, I have also created a very simple script called upgrade-system.sh. You can store it within /usr/bin/upgrade-system.sh and it can be invoked for performing system upgrades. Before starting the installation of the packages updated, the script creates a new snapshot. Then, pacman, yay and snapd are launched to upgrade the system. If something went wrong, you can restore the root filesystem using the last snapshot created. This script can be found here

Configuration files

In this folder you can find all the configuration files edited or created during the installation process.

Approach 2 [BIOS,MBR and GRUB]

First, it was necessary to disable UEFI mode and enabling legacy BIOS. Then, I partitioned the system using only two partitions: sda1 for / (including boot partition and home and sda2 for swap. I installed GRUB as a boot loader.

Graphics and Optimus installation

The laptop has two graphic cards: Integrated: Intel i915 and discrete NVIDIA GTX 960M. Then, it is interesting to have optimus technology enabled and working fine. This way, NVIDIA graphics card will only be used when a game is executed, saving power and extending battery life. These are the steps followed to have this technology working on this hardware (it was a little tricky).

++Note:++ For a stable installation, it is recommended a LTS system instead of a cutting edge one. Because of this, I installed linux-lts and linux-lts-headers instead of normal kernel and nvidia-lts and bbswitch-lts from the repository.

For the graphics cards installation and Optimius:

• Install video graphic drivers: Intel including vulkan support and bumblebee with NVIDIA

• Install primus and lib32-primus

• We will add three kernel boot parameters in GRUB. Edit /etc/default/grub and change GRUB_CMDLINE_LINUX_DEFAULT. The line should be like this (I have removed quiet in order to see all the details of the booting process and check that evrything is OK):

  GRUB_CMDLINE_LINUX_DEFAULT="i915.enable_rc6=0 pcie_port_pm=off acpi_osi=\"!Windows 2015\""
  

  The three kernel boot parameters added are:

  • Kernel boot parameter for Skylake i915 GPU.
  • If you are using kernel 4.8 or higher, add kernel boot parameter pcie_port_pm=off as you can see here for avoiding error "Could not insert 'nvidia': No such device"
  • Kernel boot parameter acpi_osi="!Windows 2015" for avoiding the system freezes when we enable bumblebeed.service.

  Finally, execute sudo grub-mkconfig -o /boot/grub/grub.cfg in order to rebuild grub configuration with all these changes.

• Add modules intel_agp and i915 (intel_agp must go always before i915) as you can see here within mkinitcpio.conf in order to enable KMS during the initramfs stage. This will avoid a black screen and will prevent the system to freeze. Rebuild initramfs using mkinitcpio -p linux or mkinitcpio -p linux-lts depending on the kernel you have installed.

• Install bbswitch for graphic cards power management: sudo pacman -S bbswitch (if you are using linux-lts or custom kernel, bbswitch-dkms is recommended)

• Finally, execute lspci and take note of the ID for the NVIDIA card (01:00.1 in my case for example). Edit this file sudo nano /etc/bumblebee/xorg.conf.nvidia and uncomment the line BusID "PCI:01:00:0" writing there the ID you obtained before.

• For launching Steam games and use NVIDIA graphics card, open Steam --> Library --> right click on the game you want to launnch --> Set Launch Options -> Type: optirun -b primus %command%

• For launching wine games and use NVIDIA graphics card, launch the game with env WINEPREFIX="/home/egarcia/.wine" /usr/bin/optirun -b primus wine C:\windows\command\start.exe /Unix /home/egarcia/.wine/dosdevices/c:/users/Public/Escritorio/Hearthstone.lnk. Another method is, for example to execute Battle.net with wine, execute de exe file using optirun -b primus wine "C:\Program Files (x86)\Battle.net\Battle.net.exe"

Resources

Antergos Wiki for Bumblebee, NVIDIA and Optimus

Bluetooth installation

Normally, bluetooth chipset (intel/ibt-11-5.sfi) should work out of the box, but there is a problem loading btusb kernel module. In order to make it work, it is necessary to create a script in /usr/bin called start-bluetooth.sh with this content:

#!/bin/bash
modprobe -r btusb
modprobe btusb

++Tip:++ If you want, you can create a desktop launcher and locate it within ~/.local/share/applications with this content:

[Desktop Entry]
Comment[en_US]=
Comment=
Exec=gksudo /usr/bin/start-bluetooth.sh
GenericName[en_US]=
GenericName=
Icon=preferences-system-bluetooth
MimeType=
Name[en_US]=Bluetooth
Name=Bluetooth
Path=
StartupNotify=true
Terminal=false
TerminalOptions=
Type=Application
X-DBUS-ServiceName=
X-DBUS-StartupType=
X-KDE-SubstituteUID=false
X-KDE-Username=

Problem with Docker and BTRFS

More than a problem is a caveat. If the main filesystem for root is BTRFS, docker will use BTRFS storage driver (Docker selects the storage driver automatically depending on the system's configuration when it is installed) to create and manage all the docker images, layers and volumes. It is ok, but there is a problem with snapshots. Because /var/lib/docker is created to store all this stuff in a BTRFS subvolume which is into root subvolume, all this data won't be included within the snapshots. In order to allow all this data be part of the snapshots, we can change the storage driver used by Docker. The preferred one is overlay2 right now. Please, check out this reference in order to select the proper storage driver for you. You must know that depending on the filesystem you have for root, some of the storage drivers will not be allowed.

For using overlay2:

• Install docker
• Create a file called storage-driver.conf within /etc/systemd/system/docker.service.d/. If the directory doens't exist, create the directory first.

sudo mkdir -p /etc/systemd/system/docker.service.d/
sudo nano /etc/systemd/system/docker.service.d/storage-driver.conf

• This is the content of storage-driver.conf

[Service]
ExecStart=
ExecStart=/usr/bin/dockerd -H fd:// --storage-driver=overlay2

• Create /var/lib/docker/ and disable CoW (copy on write for BTRFS):

sudo chattr +C /var/lib/docker

• Enable and start the service

sudo systemctl enable docker.service
sudo systemctl start docker.service

• Add your user to docker group in order to use docker command without sudo superpowers!

Pulseaudio high battery consuption

Using Energy Information application provided by KDE Plasma, I realized that pulseaudio daemon was eating the energy of my battery in a very strange way. Then I realized that it was a bug described here. To fix this bug, it is necessary to manually force power save for the audio codec:

• Before proceeding, in a terminal launch the following command:

  cat /sys/module/snd_hda_intel/parameters/power_save*
  

  if the result is different from:

  1
  Y
  

  then try the following commands

  echo 1 | sudo tee /sys/module/snd_hda_intel/parameters/power_save
  echo Y | sudo tee /sys/module/snd_hda_intel/parameters/power_save_controller
  pkill pulseaudio
  

• Log out and log in again to get pulseaudio restarted.

No sound over the headphones after suspending

This laptop is a Clevo and there is a known issue about this model: after suspending, there is no sound over the headphones anymore.

To solve this issue:

yay -S init-headphones
sudo systemctl start init-headphones
sudo systemctl enable init-headphones

After this, edit /etc/default/grub and add this flag to GRUB_CMDLINE_LINUX_DEFAULT:

acpi_enforce_resources=lax

Then, rebuild grub configuration:

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

Restructuring BTRFS Layout on Antergos or another distribution

• I have installed Antergos (Arch-based distro easy to install and to go without too much configuration) on a PC (using BIOS legacy mode instead UEFI) that I needed to work inmediately. I used BTRFS too for the installation, but the problem is that you cannot choose the layout you want for your BTRFS volume. Instead, all the root system is installed directly in the top volume itself, but I want a more refined layout (the layout defined above) in order to manage all the snapshots in a more proper way. Because of that, I detailed all the steps I made in order to mmigrate my installation to a customize layout. Once the system is installed, reboot and open a terminal to see the structure of the BTRFS volume for /:

sudo btrfs subvolume list /
cd /

Create all the subvolumes on / except rootvol subvolume:

sudo btrfs subvolume create _active
sudo btrfs subvolume create _snapshots

Now, it is necessary to make a read-write snapshot of / into _active/rootvol

sudo btrfs subvolume snapshot / /_active/rootvol

Reboot the system using Archlinux LiveCD or Antergos LiveCD. Once the system is booted, mount all the structure within /mnt using as root /_active/rootvol (in my case, / is in /dev/sda1 and /home is in /dev/sdb2):

mount -o subvol=/_active/rootvol /dev/sda1 /mnt
mount /dev/sdb2 /mnt/home

Chroot the new system:

arch-chroot /mnt /bin/bash

Add btrfs as HOOK within /etc/mkinitcpio.conf and rebuild images:

mkinitcpio -p linux

Create a new directory called defvol within /mnt

mkdir /mnt/defvol

Modify fstab to reflect the changes (remember to modify / entry and point it to /_active/rootvol. Add /tmp line too). It is interesting to add /mnt/defvol in order to mount the entire volume as it is described above too. Systemd sometimes creates /var/lib/machines subvolume so add it too. The fstab file should look like this:

# /etc/fstab: static file system information.

# Use 'blkid' to print the universally unique identifier for a
# device; this may be used with UUID= as a more robust way to name devices
# that works even if disks are added and removed. See fstab(5).
#
# <file system> <mount point>   <type>  <options>       <dump>  <pass>
#
UUID=238a2358-8bf6-47a9-907f-47eaece88632 /home ext4 defaults,rw,relatime,data=ordered 0 0
UUID=ce5c80f2-9edd-42f6-b920-d8ae43ac461b / btrfs defaults,rw,noatime,compress=lzo,ssd,discard,space_cache,autodefrag,inode_cache,subvol=_active/rootvol 0 0
UUID=ce5c80f2-9edd-42f6-b920-d8ae43ac461b /var/lib/machines btrfs defaults,rw,noatime,compress=lzo,ssd,discard,space_cache,autodefrag,inode_cache,subvol=/var/lib/machines 0 0
UUID=ce5c80f2-9edd-42f6-b920-d8ae43ac461b /mnt/defvol btrfs defaults,rw,noatime,compress=lzo,ssd,discard,space_cache,autodefrag,inode_cache,subvol=/ 0 0
UUID=4621e43f-3b86-4fa2-9d9e-823a564572f4 swap swap defaults 0 0

Reinstall GRUB (in my case, the PC was installed in BIOS legacy mode and GRUB is installed on /dev/sda):

grub-install --target=i386-pc /dev/sda
grub-mkconfig -o /boot/grub/grub.cfg

Exit chroot and unmount everything.

exit
umount /mnt -R

Reboot. Once the system is booted, check if / is pointing to /_active/rootvol. If everything is working fine, all the files within the root of the volume can be deleted.

cd /mnt/defvol
sudo rm -rf b*
sudo rm -rf d*
sudo rm -rf e*
sudo rm -rf h*
sudo rm -rf l*
sudo rm -rf m*
sudo rm -rf o*
sudo rm -rf p*
sudo rm -rf r*
sudo rm -rf s*
sudo rm -rf t*
sudo rm -rf u*

At this point, only _active, _snapshots and var should exist within /mnt/defvol. Go to /mnt/defvol/_active/rootvol and you can safely delete _active and _snapshots:

cd /mnt/defvol/_active/rootvol
sudo rm -rf _active
sudo rm -rf _snapshots

DONE!!! :) This is the original post from I got the inspiration to do this stuff.

Do you want to contact me?

For more information, please check my portfolio web page at https://egara.github.io