BTRFS is a copy on write filesystem (COW)

Unlike journaling file systems like ext4, BTRFS does not overwrite the data when it is modified, instead it writes the data to a new block and changes metadata to point to the latest version of the file. This provides better protection against power failures.

Snapshots

BTRFS offers fast incremental snapshot creation and tools to backup and restore.

Creating the file system and btrfs partition

parted /dev/nvmexxx
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) mklabel gpt
(parted) mkpart primary btrfs 4MiB 100%
(parted) print
(parted) quit

after the partition is created, create the btrfs file system on it by running

sudo mkfs.btrfs /dev/sdxy

Mounting the partition

Temporary mount with

sudo mount /dev/sdxy /mountpoint

Show info about the btrfs

To see the UUID, size, usage of all btrfs disks.

sudo btrfs filesystem show

See detailed disk usage

sudo btrfs filesystem usage /Subvol

Creating the subvolumes

To create a subvolume called data

sudo btrfs subvolume create /mountpoint/data

List all the subvolumes

To create a subvolume called data

sudo btrfs subvolume list /mountpoint/data

Mounting the subvolumes

to make the mount permanent, edit the ‘/etc/fstab’ file

UUID=DISKUUUD /MOUNTPOINT   btrfs   defaults,noatime,commit=120,compress=zstd:1 0 0

{: .nolineno file=“/etc/fstab” } These are mount options for the root subvol

  • noatime : Do not modify metadata on file read. Reduces disk writes.
  • commit=120: Time interval for writing changes to disk. Default is 30. Reduces disk writes.
  • compress=zstd:1 : Filesystem level compression. Reduces disk writes.

Create a readonly snapshot of a subvolume

sudo btrfs subvolume snapshot -r /data /data/.snapshots/name

Copying snapshots to other drives using send, receive

Send and receive is faster than rsync. The destination must be also btrfs.

sudo btrfs send /data/.snapshots/name | sudo btrfs receive  /mnt/backupDISK/backup

Restoring from a snapshot and make the snapshot writable

Copy the snapshot to the target folder.

sudo btrfs property set -tsf /data/snapshot ro false

Creating backups of your snapshot on a remote machine

btrfs send -p /data/ /data/.snapshots/new_snaphot | ssh root@ip "btrfs receive /mnt/backups"