Btrbk local regular snapshots time machine - nutthawit/alpine-dotfile GitHub Wiki

The simplest use case is to only create snapshots of your data. This will obviously not protect it against hardware failure, but can be useful for:

protection against inadvertent changes or deletions
keeping past states of copies from rsync or similar tools

Let's assume you need regular snapshots of your / directory (root filesystem), which is located in the subvolume named @ of the volume /mnt/btr_pool. The snapshots are to be stored in btrbk_snapshots

Prerequisite

Btrbk setup

Configuration

First create btrbk_snapshots directory

mkdir /mnt/btr_pool/btrbk_snapshots

And create /etc/btrbk/btrbk.conf with following content:

compat busybox

timestamp_format long
snapshot_preserve_min 8h
snapshot_preserve 16h

snapshot_dir /mnt/btr_pool/btrbk_snapshots
subvolume /mnt/btr_pool/@

[!CAUTION] The compat busybox is required, to tell btrbk use readlink from busybox instead of coreutils. Read more

snapshot_dir is directory in which the btrfs snapshots are created. For more options that btrbk.conf support look at https://digint.ch/btrbk/doc/btrbk.conf.5.html

Start a dry run (-n, --dry-run):

btrbk run -n

If you see output like the one below, it means it is working correctly.

/mnt/btr_pool/@
+++ /mnt/btr_pool/btrbk_snapshots/@.20251003T0753

If it works as expected, configure a busybox crond to run btrbk hourly:

mkdir /etc/periodic/30min
touch /etc/periodic/30min/btrbk && chmod +x /etc/periodic/30min/btrbk
vi /etc/periodic/30min/btrbk

Add following content to /etc/periodic/30min/btrbk:

#!/bin/sh
exec /usr/bin/btrbk -q run

Add 30min entry to /etc/crontabs/root:

# do daily/weekly/monthly maintenance
# min   hour    day     month   weekday command
*/15    *       *       *       *       run-parts /etc/periodic/15min
*/30    *       *       *       *       run-parts /etc/periodic/30min
0       *       *       *       *       run-parts /etc/periodic/hourly
0       2       *       *       *       run-parts /etc/periodic/daily
0       3       *       *       6       run-parts /etc/periodic/weekly
0       5       1       *       *       run-parts /etc/periodic/monthly

Start crond service

rc-service crond start
rc-update add crond
rc-service crond restart

Snapshots will now be created every 30 min. All snapshots are preserved for at least 8 hours (snapshot_preserve_min), whether they are created by the cron job or manually by calling sudo btrbk run on the command line. Additionally, 16 hourly snapshots are preserved (snapshot_preserve).

[!TIP] If you want to start root_fs snapshot immediately run: btrbk snapshot @ Read more

Todo

Currently it's not work with sync-cron, instead we must used async-cron

Btrbk local regular snapshots time machine - nutthawit/alpine-dotfile GitHub Wiki

Prerequisite

Configuration

See also

Todo