Simplified guide on taking snapshots on Btrfs with btrfs-assistant

Are you a Linux user who frequently modifies system configurations but worries about potential system failures? System snapshots offer a reliable safety net, allowing you to restore your system if something goes wrong.

While Snapper is a powerful tool for managing Btrfs snapshots, it requires configuration file editing that some users find challenging. This guide introduces btrfs-assistant, a user-friendly graphical tool that simplifies the snapshot management process on Btrfs filesystems.

Installation

Arch

Btrfs Assistant can be installed from the AUR as btrfs-assistant

Debian

There are unofficial Debian packages here coutesy of @idesmi or you can follow the instructions for Ubuntu to build it yourself.

Ubuntu

Install Snapper package using this command:

sudo apt install snapper

Fedora

Btrfs Assistant is available in the Fedora repos as btrfs-assistant

Btrfs Assistant

Configure snapshot through btrfs-assistant

Head over to Snapper setting tab (if you dont see it, install snapper package), enter config name, select subvolume to back up and choose needed systemd settings and press Save. Now Timely snapshot interval settings will pop-up. I want to select the snapshot on boot with grub and clean old snapshots to save up space. This is my config to back up /home subvolume

This setting will take one snapshot every day.

Btrfs Assistant also allows you to take manual snapshot and manage your snapshots easier

My Arch installation using archinstall script using Btrfs with LUKS encryption has created the /.snapshots directory already but I can’t seems to add my own configuration on it so we need a little tweak to get it working us way

Unmount the subvolume and remove the mountpoint … (yes you can use rm -rf to remove subvolumes)

sudo umount /.snapshots
sudo rm -rf /.snapshots

Use grub-btrfs to boot from snapshots

Note

Snapper’s snapshots are read-only, and there are some inherent difficulties booting into read-only snapshots. Many services, such as a desktop manager, require a writable /var directory, and will fail to start when booted from a read-only snapshot.

To work around this, you can either make the snapshots writable, or use the developer-approved method of booting the snapshots with overlayfs, causing the snapshot to behave similar to a live CD environment.

To boot snapshots with overlayfs

• Ensure grub-btrfs is installed on your system.
• Add grub-btrfs-overlayfs to the end of the HOOKS array in /etc/mkinitcpio.conf. For example:

HOOKS=(base udev autodetect microcode modconf kms keyboard keymap consolefont block filesystems fsck grub-btrfs-overlayfs)

• Regerate the initramfs.

sudo mkinitcpio -P

• Set the location of the directory containing the grub.cfg file in /etc/default/grub-btrfs/config.

Example: EndeavousOS’s grub.cfg is located in /efi/grub and my Arch Linux’s is in /boot/grub

GRUB_BTRFS_GRUB_DIRNAME="/boot/grub"

Auto-update GRUB

Enable grub-btrfs.path to auto-regenerate grub-btrfs.cfg whenever a modification appears in /.snapshots …

sudo systemctl enable --now grub-btrfs.path

More info check out grub-btrfs

System rollback the ‘Arch Way’

Snapper includes a rollback tool, but on Arch systems the preferred method is a manual rollback.

After booting into a snapshot mounted rw courtesy of overlayfs, mount the toplevel subvolume (subvolid=5). That is, omit any subvolid or subvol mount flags (example: an encrypted device map labelled cryptdev) …

sudo mount /dev/mapper/cryptdev /mnt

Move the broken @ subvolume out of the way …

sudo mv /mnt/@ /mnt/@.broken

Or simply delete the subvolume …

sudo btrfs subvolume delete /mnt/@

Find the number of the snapshot that you want to recover …

sudo grep -r '<date>' /mnt/@snapshots/*/info.xml
[...]
/.snapshots/8/info.xml:  <date>2022-08-20 15:21:53</date>
/.snapshots/9/info.xml:  <date>2022-08-20 15:22:39</date>

Create a read-write snapshot of the read-only snapshot taken by Snapper …

sudo btrfs subvolume snapshot /mnt/@snapshots/number/snapshot /mnt/@

Where number is the snapshot you wish to restore as the new @.

Unmount /mnt.

Reboot and rollback!