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Using rsnapshot for easy backups

Written by Solène, on 10 January 2020.
Tags: #openbsd

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Introduction

rsnapshot is a handy tool to manage backups using rsync and hard links on the filesystem. rsnapshot will copy folders and files but it will skip duplication over backups using hard links for files which has not changed.

This kinda create snapshots of your folders you want to backup, only using rsync, it’s very efficient and easy to use, and getting files from backups is really easy as they are stored as files under the rsnapshot backup.

Installation

Installing rsnapshot is very easy, on most systems it will be in your official repository packages.

To install it on OpenBSD: pkg_add rsnapshot (as root)

Configuration

Now you may want to configure it, in OpenBSD you will find a template in /etc/rsnapshot.conf that you can edit for your needs (you can make a backup of it first if you want to start over). As it’s stated in big (as big as it can be displayed in a terminal) letters at the top of the configuration sample file, you will see that things must be separated by TABS and not spaces. I’ve made the mistakes more than once, don’t forget using tabs.

I won’t explain all options, but only the most importants.

The variable snapshot_root is where you want to store the backups. Don’t put that directory in a directory you will backup (that will end into an infinite loop)

The variable backup is for telling rsnapshot what you want to backup from your system to which directory inside snapshot_root

Here are a few examples:

backup  /home/solene/   myfiles/
backup  /home/shera/Documents   shera_files/
backup  /home/shera/Music   shera_files/
backup  /etc/   etc/
backup  /var/   var/    exclude=logs/*

Be careful when using ending slashes to paths, it works the same as with rsync. /home/solene/ means that into target directory, it will contains the content of /home/solene/ while /home/solene will copy the folder solene within the target directory, so you end up with target_directory/solene/the_files_here.

The variables retain are very important, this will define how rsnapshot keep your data. In the example you will see alpha, beta, gamma but it could be hour, day, week or foo and bar. It’s only a name that will be used by rsnapshot to name your backups and also that you will use to tell rsnapshot which kind of backup to do. Now, I must explain how rsnapshot actually work.

How it work

Let’s go for a straighforward configuration. We want a backup every hour on the last 24h, a backup every day for the past 7 days and 3 manuals backup that we start manually.

We will have this in our rsnapshot configuration

retain  hourly  24
retain  daily   7
retain  manual  3

but how does rsnapshot know how to do what? The answer is that it doesn’t.

In root user crontab, you will have to add something like this:

# run rsnapshot every hour at 0 minutes
0 * * * * rsnapshot hourly

# run rsnapshot every day at 4 hours 0 minutes
0 4 * * * rsnapshot daily

and then, when you want to do a manual backup, just start rsnapshot manual

Every time you run rsnapshot for a “kind” of backup, the last version will be named in the rsnapshoot root directory like hourly.0 and every backups will be shifted by one. The directory getting a number higher than the number in the retain line will be deleted.

New to crontab?

If you never used crontab, I will share two important things to know about it.

Use MAILTO=“” if you don’t want to receive every output generated from scripts started by cron.

Use a PATH containing /usr/local/bin/ in it because in the default cron PATH it is not present. Instead of setting PATH you can also using full binary paths into the crontab, like /usr/local/bin/rsnapshot daily

You can edit the current user crontab with the command crontab -e.

Your crontab may then look like:

PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/X11R6/bin:/usr/local/bin:/usr/local/sbin
MAILTO=""
# comments are allowed in crontab
# run rsnapshot every hour at 0 minutes
0 * * * * rsnapshot hourly
# run rsnapshot every day at 4 hours 0 minutes
0 4 * * * rsnapshot daily