Snapshots and recovery

CatOS uses Btrfs for subvolume snapshots, Snapper for snapshot metadata and retention, and bootloader-specific integration for bootable snapshots.

Automatic and bootable snapshots require a Btrfs root filesystem, a working Snapper root configuration, and a supported boot method.

Boot method	Snapshot menu integration
GRUB	grub-btrfs
Limine	limine-btrfs
systemd-boot	sdboot-btrfs
UKI	Not configured automatically
EFI Stub	Not configured automatically

Automatic CatOS snapshots

catos-snapper-config evaluates a pacman transaction before it runs. It creates a single pre-transaction snapshot when either:

• the transaction touches kernel, initramfs, firmware, DKMS, UKI, encryption, or other boot-critical paths; or
• the transaction changes at least 25 distinct packages.

Small ordinary application installs normally do not create a snapshot, and hourly timeline snapshots are disabled by default.

cat /etc/catos-snapper.conf
snapper list

Inspect changes relative to the current system:

snapper status NUMBER..0
snapper diff NUMBER..0

Create a manual snapshot before a risky change:

sudo snapper -c root create \
  --type single \
  --cleanup-algorithm number \
  --description 'Before manual system change'

Booting versus rolling back

Booting a historical snapshot is useful for diagnosis and data recovery, but does not by itself make that snapshot the permanent root state. A real rollback must account for the target snapshot, current data, kernel and initramfs resources, and the selected bootloader workflow.

Do not manually change the default Btrfs subvolume or make a read-only snapshot writable without understanding the installed subvolume layout.

Boot resources

A root snapshot may not include the kernel and initramfs stored under /boot. CatOS GRUB, Limine, and systemd-boot integrations therefore maintain the snapshot menu and required boot resources instead of merely listing .snapshots directories.

Cleanup

systemctl status snapper-cleanup.timer
sudo btrfs filesystem usage /
snapper list

Delete a confirmed snapshot with:

sudo snapper delete NUMBER

Snapshots normally remain on the same filesystem and disk. They do not protect against device loss, full-disk formatting, or filesystem-wide damage, so important data still needs an independent backup.