This is a guide to install Pop!_OS (version 20.10 at the time of writing this) with btrfs instead of ext4 to allow the use of subvolumes and timeshift for continuous backup.
This guide has been adapted from Willi Mutschler's excellent guide found here that also includes Luks encryption using LVM. My version does not use encryption (as I use hardware encryption for my SSD), so if you need encryption, please follow his guide. All credit for this work belongs to Willi Mutschler.
The use of btrfs allows snapshot backups of the file system with timeshift. These take minimal space and make it easy to restore to a previous state if needed. Btrfs appears to be mature enough for mainstream use, with minimal performance hit, and is offered by default during Pop!_OS installation.
This quide requires the ability to perform tasks using the terminal. It also expects the user to have basic understaning of:
- What is a filesystem
- What is a partitions
- A boot manager and a bootloader
- What chroot does
and ability to:
- Boot a PC from USB
- Create and edit partitions using various tools (parted, gparted or fdisk)
- Install Pop!_OS in advance mode
- Edit files using nano or other editors (vim or graphically gedit)
This guide expects a UEFI system so please check as soon as you have your USB live system running, from a terminal with mount | grep efivars and expect an output like
efivarfs on /sys/firmware/efi/efivars type efivarfs (rw,nosuid,nodev,noexec,relatime)
This means the system is in UEFI mode. If not, change your Bios settings to UEFI and start over.
The installation is done in three parts. Preparing the system, installing the system, configuring the system. All are done from within the USB Live environment. As such the first step is to boot the system from USB to Pop!_OS Live Environment. Once the system is up, go through the stages to select keyboard and languange, and then exit the installer by selecting Try Demo Mode.
Open a terminal (Super+T) and change to interactive root with sudo -i. Keep this terminal open at all times.
To install Pop!_OS we will need three partitions (including the recovery).
- A 512MB Fat32 partition for
/boot/efi - A 4096MB Fat32 partition for
/recovery - A linux partition (no filesystem yet) for
/
Type lsblk to see your storage devices and partitions.
NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT
sdc 8:32 0 465.8G 0 disk
└─sdc1 8:33 0 465.8G 0 part
The above shows my device, a 500GB SSD that currently has a single partition. I will use this as an example for this guide. Yours might be different of course.
To start partitioning this device, start fdisk.
Note: All data on this drive will be deleted
root@pluto:~# fdisk /dev/sdc
Welcome to fdisk (util-linux 2.36).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help):
Now enter p to print the current layout.
Disk /dev/sdc: 465.76 GiB, 500107862016 bytes, 976773168 sectors
Disk model: MobileDataStar
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 7539C5AF-685B-42F6-BC85-27E26461002E
Device Start End Sectors Size Type
/dev/sdc1 2048 976773134 976771087 465.8G Linux filesystem
Command (m for help):
We first need to delete the current partition to start fresh. For that I type d for delete
Disk /dev/sdc: 465.76 GiB, 500107862016 bytes, 976773168 sectors
Disk model: MobileDataStar
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 7539C5AF-685B-42F6-BC85-27E26461002E
Device Start End Sectors Size Type
/dev/sdc1 2048 976773134 976771087 465.8G Linux filesystem
Command (m for help):
Time to start partitioning.
First partition is the ESP partition (EFI System Partition), as stated above. Type n to create new partition.
Command (m for help): n
Partition number (1-128, default 1): ← press enter
First sector (34-976773134, default 2048): ← press enter
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-976773134, default 976773134): +512M *← type 512M for the size required
Created a new partition 1 of type 'Linux filesystem' and of size 512 MiB.
Command (m for help): p ← type p to show partitions
Disk /dev/sdc: 465.76 GiB, 500107862016 bytes, 976773168 sectors
Disk model: MobileDataStar
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 7539C5AF-685B-42F6-BC85-27E26461002E
Device Start End Sectors Size Type
/dev/sdc1 2048 1050623 1048576 512M Linux filesystem ← the new partition is here
Command (m for help):
Create the other two in the same way.
Command (m for help): n
Partition number (2-128, default 2): ← press enter
First sector (1050624-976773134, default 1050624): ← press enter
Last sector, +/-sectors or +/-size{K,M,G,T,P} (1050624-976773134, default 976773134): +4096M ← type 4096M for the size required
Created a new partition 2 of type 'Linux filesystem' and of size 4 GiB.
Command (m for help): n
Partition number (3-128, default 3): ← press enter
First sector (9439232-976773134, default 9439232): ← press enter
Last sector, +/-sectors or +/-size{K,M,G,T,P} (9439232-976773134, default 976773134): ← press enter to use all remaining space
Created a new partition 3 of type 'Linux filesystem' and of size 461.3 GiB.
Command (m for help): p ← to show the new partition layout
Disk /dev/sdc: 465.76 GiB, 500107862016 bytes, 976773168 sectors
Disk model: MobileDataStar
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 7539C5AF-685B-42F6-BC85-27E26461002E
Device Start End Sectors Size Type
/dev/sdc1 2048 1050623 1048576 512M Linux filesystem
/dev/sdc2 1050624 9439231 8388608 4G Linux filesystem
/dev/sdc3 9439232 976773134 967333903 461.3G Linux filesystem
Filesystem/RAID signature on partition 1 will be wiped.
Your three partitions are created, and the last warning is to remind you there was a filesystem on this drive that will be deleted as soon as you write the changes. Do not write or exit fdisk yet.
We need to set partition type for the ESP partition, so that the BIOS knows it is an ESP partition and try to boot from it.
Type t to change partition type, as follows.
Command (m for help): t Partition number (1-3, default 3): 1 ← select the first partition Partition type or alias (type L to list all): 1 ← select partition type 1, EFI System Changed type of partition 'Linux filesystem' to 'EFI System'. Command (m for help): p Disk /dev/sdc: 465.76 GiB, 500107862016 bytes, 976773168 sectors Disk model: MobileDataStar Units: sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 4096 bytes I/O size (minimum/optimal): 4096 bytes / 4096 bytes Disklabel type: gpt Disk identifier: 7539C5AF-685B-42F6-BC85-27E26461002E Device Start End Sectors Size Type /dev/sdc1 2048 1050623 1048576 512M EFI System /dev/sdc2 1050624 9439231 8388608 4G Linux filesystem /dev/sdc3 9439232 976773134 967333903 461.3G Linux filesystem Filesystem/RAID signature on partition 1 will be wiped.
You can see when we print the partition layout now, the partition type of the first partition is set to EFI System.
Let's finish off by adding labels. For this we need the extra functionality so type x. We name the second partition RECOVERY and the third partition ROOT.
Command (m for help): x Expert command (m for help): n Partition number (1-3, default 3): 2 New name: RECOVERY Partition name changed from '' to 'RECOVERY'. Expert command (m for help): n Partition number (1-3, default 3): 3 New name: ROOT Partition name changed from '' to 'ROOT'.
Now exit the extra functionality menu by typing r
Expert command (m for help): r
You can now write the new partition layout by typing w. This will exit fdisk.
You can now start the installer from the dash favourite menu. You will select Custom (Advanced). Then you will select the partitions and proceed as follows:
- Select the first partition, Use partition, Format, and set for /boot/efi and filesystem fat32.
- Select the second partition, Use partition, Format, and set for Custom and type:
/recoveryand filesystem fat32. - Select the third partition, Use partition, Format, and set for / and filesystem btrfs ← this is the main change!
You do not need a swap partition, we will install a swapfile!
Now press Erase and Install and wait for it to finish. When done DO NOT REBOOT. Instead go back to your terminal.
Let me retype this DO NOT REBOOT
Note: At this point you could reboot and use your system as it is, but you would have no subvolumes and as such no access to btrfs main benefits.
You're using the terminal, still in root interactive mode (sudo -i).
First mount the ROOT partition to /mnt
mount -o subvolid=5,ssd,noatime,space_cache,commit=120,compress=zstd /dev/sdc3 /mnt
These options are suggested for better performance with btrfs (taken from Willi Mutschler site as they appear):
- ssd: use SSD specific options for optimal use on SSD and NVME
- noatime: prevent frequent disk writes by instructing the Linux kernel not to store the last access time of files and folders
- space_cache: allows btrfs to store free space cache on the disk to make caching of a block group much quicker
- commit=120: time interval in which data is written to the filesystem (value of 120 is taken from Manjaro’s minimal iso)
- compress=zstd: allows to specify the compression algorithm which we want to use. btrfs provides lzo, zstd and zlib compression algorithms. Based on some Phoronix test cases, zstd seems to be the better performing candidate.
Now you have your newly installed system mounted on /mnt. We are going to make 3 subvolumes:
- @ for root
/ - @home for home
/home - @swap for, well, swap
/swap
Create subvolume '/mnt/@'
root@pluto:/# btrfs subvolume create /mnt/@
With the @ subvolume created, we need to move all the data except for /home from the old / to the new /, under the @ subvolume. NB : We are not moving /home right now as we will copy it later into the proper subvolume.
root@pluto:/# cd /mnt root@pluto:/# ls | grep -v '@\|home' | xargs mv -t @
The second command moved all files and folders, except the home directory, to /mnt/@.
If we check now in /mnt, there is nothing but the subvolume @. If you check inside of it you will find all installation data.
root@pluto:/# ls /mnt/ @ root@pluto:/# cd @ root@pluto:/# ls bin dev home lib32 libx32 mnt proc root sbin swap tmp var boot etc lib lib64 media opt recovery run srv sys usr
Now for the other two subvolumes.
Create subvolume '/mnt/@home'
root@pluto:/# btrfs subvolume create /mnt/@home root@pluto:/# mv ./home/ ./@home
The second command ensured that all data from /home were written into ./@home.
Create subvolume '/mnt/@swap'
root@pluto:/# btrfs subvolume create /mnt/@swap root@pluto:/# btrfs subvolume list /mnt ID 263 gen 66 top level 5 path @ ID 264 gen 64 top level 5 path @home ID 265 gen 66 top level 5 path @swap
Your ID numbers may differ.
We're almost done, except for the swap.
The @swap subvolume appears as a folder inside of the /mnt mount. In there we're creating the swapfile. For this example I'm using a 9GB swapfile (to allow for suspend-to-disk, aka hibernate -not covered in this guide).
Follow the series of commands:
root@pluto:/# truncate -s 0 /mnt/@swap/swapfile root@pluto:/# chattr +C /mnt/@swap/swapfile root@pluto:/# btrfs property set /mnt/@swap/swapfile compression none root@pluto:/# fallocate -l 9G /mnt/@swap/swapfile ← here you decide the size of the swapfile, 9G used for 9GB root@pluto:/# chmod 600 /mnt/@swap/swapfile root@pluto:/# mkswap /mnt/@swap/swapfile Setting up swapspace version 1, size = 9 GiB (9663676416 bytes) no label, UUID=a0fee436-e38a-4d60-bb40-680c221db376 mkdir /mnt/@/swap
The last command has created a swap folder inside the / root. We will mount the @swap subvolume to that folder to make it a appear as a swap partition to the filesystem.
For that we need to edit /etc/fstab. The new one, not the one on the system we currently use (which is the live environement.
To edit the new fstab file do nano /mnt/@/etc/fstab
Remember: The installation is now found in the @ subvolume which is accessible from the /mnt/@ point. As such the /etc folder of the new installation is there /mnt/@/etc.
It is helpful to have the UUID of the partition your btrfs system lives. For that do lsblk -f.
NAME FSTYPE FSVER LABEL UUID sdb ├─sdc1 vfat FAT32 0BAC-7FA8 ├─sdc2 vfat FAT32 7827-FA9E ├─sdc3 btrfs 78c9787f-1d36-42e8-89bd-7b94b501afaf
In the case above the UUID is 78c9787f-1d36-42e8-89bd-7b94b501afaf. Normally this should already be in your fstab, but have it handy in case you need it.
Now have your /mnt/@/etc/fstab 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). # # PARTUUID=697685f3-e003-4cd4-a7be-b07bbcf4497e /boot/efi vfat umask=0077 0 0 PARTUUID=a9fbe686-9f08-487c-9bc9-db094845b8c2 /recovery vfat umask=0077 0 0 UUID=78c9787f-1d36-42e8-89bd-7b94b501afaf / btrfs defaults,subvol=@,ssd,noatime,space_cache,commit=120,compress=zstd 0 0 UUID=78c9787f-1d36-42e8-89bd-7b94b501afaf /home btrfs defaults,subvol=@home,ssd,noatime,space_cache,commit=120,compress=zstd 0 0 UUID=78c9787f-1d36-42e8-89bd-7b94b501afaf /swap btrfs defaults,subvol=@swap,compress=no 0 0 /swap/swapfile none swap defaults 0 0
Note that the UUID is the same for all system mounts except for the /boot/efi and the /recovery that use their PARTUUID, and you do not change these.
The bootloader does not expect the root / to be on a subvolume. We need to tell it where to find it.
Pop!_OS uses systemd_boot and this makes things very simple.
First, mount the new /boot/efi to edit the configuration files. We need to mount this in its proper location, so:
mount /dev/sdc1 /mnt/@/boot/efi
Now, the main change is in the entry file that boots Pop!_OS
That file is /mnt/@/boot/efi/loader/entries/Pop_OS-current.conf
Edit it with nano and at the end of the last line (that starts with options) add: rootflags=subvol=@
The complete file should look like this:
title Pop!_OS linux /EFI/Pop_OS-78c9787f-1d36-42e8-89bd-7b94b501afaf/vmlinuz.efi initrd /EFI/Pop_OS-78c9787f-1d36-42e8-89bd-7b94b501afaf/initrd.img options root=UUID=78c9787f-1d36-42e8-89bd-7b94b501afaf ro quiet loglevel=0 systemd.show_status=false splash rootflags=subvol=@
Look at the very last item of the last line (scroll right to see it).
Now that the bootloader knows where to find /, we need to make sure that when an update re-writes the bootloader, it doesn't remove that option.
For that we need to make that option the default everytime the bootloader is configured by the system or wen we run kernestub (the bootmanager manager -word manager appears twice here).
For that we need to edit the configuration of kernelstub that is found in the system's /etc/kernelstub/configuration file.
So edit this file with nano /mnt/@/etc/kernelstub/configuration.
We need to find the user section, that ends with "splash". We need to add "rootflags=subvol=@" after it.
Be careful, since we add one more entry to this section, the previous entry, "splash" now needs to end with a comma.
So the complete file will look like this:
{
"default": {
"kernel_options": [
"quiet",
"splash"
],
"esp_path": "/boot/efi",
"setup_loader": false,
"manage_mode": false,
"force_update": false,
"live_mode": false,
"config_rev": 3
},
"user": {
"kernel_options": [
"quiet",
"loglevel=0",
"systemd.show_status=false",
"splash", ← here is the comma added
"rootflags=subvol=@" ← here is the new option added
],
"esp_path": "/boot/efi",
"setup_loader": true,
"manage_mode": true,
"force_update": false,
"live_mode": false,
"config_rev": 3
}
The configuration is done. Now we need to rebuild the bootloader for the new configuration.
For this we need to chroot. This is taken from System76 website here for UEFI systems.
We will first umount everything from /mnt with cd / to move out of the mounted folder and then umount -l /mnt.
Now we will remount the new system (in its subvolumes) to /mnt again.
mount -o defaults,subvol=@,ssd,noatime,space_cache,commit=120,compress=zstd /dev/sdc3 /mnt
Note the above mounts the subvol=@, that is the root, to /mnt. It's a different command to the one we used earlier.
Now mount the required system partitions:
for i in /dev /dev/pts /proc /sys /run; do sudo mount -B $i /mnt$i; done
sudo cp /etc/resolv.conf /mnt/etc/
sudo chroot /mnt
If /etc/resolv.conf complains they're identical, it's fine. You need this line to have access to the internet after chroot.
Check everything is mounted as they should with:
root@pluto:/# mount -av
/boot/efi : successfully mounted
/recovery : successfully mounted
/ : ignored
/home : successfully mounted
/swap : successfully mounted
(Don't worry about the ignored statement, that's what it should be).
First install btrfs-progs to the new installation (most probably already installed) with apt install -y btrfs-progs.
If not and they install, you will see that this simple apt command had the bootloader updated and had we not changed the default configuration of kernelstub our kernel option would be gone.
Now lets update once more manually with update-initramfs -c -k all.
We're done. Type exit to leave chroot and then reboot now to restart to the new installation.
Once in the new installation, do a quick check with:
otheos@pluto:~$ sudo mount -av /boot/efi : already mounted /recovery : already mounted / : ignored /home : already mounted /swap : already mounted none : ignored
then,
otheos@pluto:~$ sudo cat /etc/fstab # /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). # # PARTUUID=697685f3-e003-4cd4-a7be-b07bbcf4497e /boot/efi vfat umask=0077 0 0 PARTUUID=a9fbe686-9f08-487c-9bc9-db094845b8c2 /recovery vfat umask=0077 0 0 UUID=78c9787f-1d36-42e8-89bd-7b94b501afaf / btrfs defaults,subvol=@,ssd,noatime,space_cache,commit=120,compress=zstd 0 0 UUID=78c9787f-1d36-42e8-89bd-7b94b501afaf /home btrfs defaults,subvol=@home,ssd,noatime,space_cache,commit=120,compress=zstd 0 0 UUID=78c9787f-1d36-42e8-89bd-7b94b501afaf /swap btrfs defaults,subvol=@swap,compress=no 0 0 /swap/swapfile none swap defaults 0 0
then,
otheos@pluto:~$ sudo swapon NAME TYPE SIZE USED PRIO /swap/swapfile file 9G 0B -2
then,
otheos@pluto:~$ sudo btrfs filesystem show / Label: none uuid: 78c9787f-1d36-42e8-89bd-7b94b501afaf Total devices 1 FS bytes used 13.82GiB devid 1 size 88.75GiB used 18.02GiB path /dev/sdb3
and
otheos@pluto:~$ sudo btrfs subvolume list / ID 263 gen 230 top level 5 path @ ID 264 gen 230 top level 5 path @home ID 265 gen 72 top level 5 path @swap
Then update your system as you would a new installation:
sudo apt update
sudo apt upgrade
sudo apt dist-upgrade
sudo apt autoremove
sudo apt autoclean
Finally install timeshift with sudo apt install -y timeshift
The following is taken from Willi Mutschler's website,
- Select “BTRFS” as the “Snapshot Type”; continue with “Next”
- Choose your BTRFS system partition as “Snapshot Location”; continue with “Next” (even if timeshift does not see a btrfs system in the GUI it will still work, so continue (I already filed a bug report with timeshift))
- “Select Snapshot Levels” (type and number of snapshots that will be automatically created and managed/deleted by Timeshift), my recommendations:
- Activate “Monthly” and set it to 1
- Activate “Weekly” and set it to 3
- Activate “Daily” and set it to 5
- Deactivate “Hourly”
- Activate “Boot” and set it to 3
- Activate “Stop cron emails for scheduled tasks” continue with “Next”
- I also include the @home subvolume (which is not selected by default). Note that when you restore a snapshot Timeshift you get the choise whether you want to restore it as well (which in most cases you don’t want to).
- Click “Finish”
- “Create” a manual first snapshot & exit Timeshift
You can find your backups in /run/timeshift/backup.
- To be added: timeshift-autosnap-apt to backup before every apt udate.