Btrbk setup - nutthawit/alpine-dotfile GitHub Wiki

Btrbk is a backup tool for btrfs subvolumes, taking advantage of btrfs specific capabilities to create atomic snapshots and transfer them incrementally to your backup locations.

Installation

Install btrbk

apk add btrbk btrbk-doc

Configuration

Mount root partition to /mnt/btr_pool and add entry to /etc/fstab

ROOT=/dev/nvme0n1p2
BTR_POOL=/mnt/btr_pool

echo "${ROOT} ${BTR_POOL} btrfs subvolid=5,noatime 0 0" | tee -a /etc/fstab
mkdir ${BTR_POOL}
mount -a
mount

[!CAUTION] Mounting subvolid=5 is mandatory if you want to backup your root filesystem /

[!NOTE] subvolid=5 is known as the fs_tree. The fs_tree is automatically created when you create a Btrfs filesystem using mkfs.btrfs

As of now, my subvolume scheme is the following:

Name	Path	Mount
@	/	/
home	/home	/home
var	/var	/var

All subvolumes are children of the top-level (ID 5). This is the output of my btrfs subvolume list / command.

ID 256 gen 176 top level 5 path @
ID 257 gen 10 top level 5 path home
ID 258 gen 173 top level 5 path var

And this is my /etc/fstab. Focus on the first three lines.

UUID=f6cfb7d1-dbcf-4680-830c-2f6aa89d8c50       /       btrfs   rw,relatime,compress=zstd:3,ssd,discard=async,space_cache=v2,subvolid=256,subvol=/@ 0 1
UUID=f6cfb7d1-dbcf-4680-830c-2f6aa89d8c50       /home   btrfs   rw,relatime,compress=zstd:3,ssd,discard=async,space_cache=v2,subvolid=257,subvol=/home 0 2
UUID=f6cfb7d1-dbcf-4680-830c-2f6aa89d8c50       /var    btrfs   rw,relatime,compress=zstd:3,ssd,discard=async,space_cache=v2,subvolid=258,subvol=/var 0 2
UUID=68D7-7AE4  /boot   vfat    rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=utf8,shortname=mixed,errors=remount-ro 0 2
/dev/cdrom      /media/cdrom    iso9660 noauto,ro 0 0
/dev/usbdisk    /media/usb      vfat    noauto  0 0
tmpfs   /tmp    tmpfs   nosuid,nodev    0       0
/dev/nvme0n1p2 /mnt/btr_pool btrfs subvolid=5,noatime 0 0

See also

https://github.com/digint/btrbk