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Incremental backups using rsnapshot

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Use the rsync powers of rsnapshot to make daily, weekly, and monthly backups of data.

I do an automatic daily backup of the home directory on my laptop to a local server. But what if I delete something on Monday, backup the modified directory, and realize on Friday “Doh! I need that!”. If I have the item saved on external storage no problem. Between daily syncs of a backup and periodic manual syncs to a portable hard drive, however, its possible that it might be weeks or months later when I realize I need something I had removed. Might there be a better way to track changes to a home backup?

Yes there is! Rsnapshot makes one complete backup, then makes incremental snapshots of that full backup that tracks any modifications. It is very resource efficient. A daily snapshot of a 100GB directory that is unchanged might be only 20MB. Good stuff!

Let’s go!

I install rsnapshot on my Debian server, make a directory to store snapshots, and make a copy of the default rsnapshot config …

$ sudo apt install rsnapshot
$ mkdir -p /path/to/backup/snapshots
$ sudo cp /etc/rsnapshot.conf /etc/rsnapshot.conf.default

Modify /etc/rsnapshot.conf (important to separate fields with TABS not spaces) 1 and (for example) uncomment the options listed below, plus create a schedule of (6) daily, (4) weekly, and (3) monthly snapshots …

snapshot_root   /path/to/backup/snapshots/

cmd_cp          /bin/cp
cmd_rm          /bin/rm
cmd_rsync       /usr/bin/rsync
cmd_logger      /usr/bin/logger
cmd_du          /usr/bin/du
cmd_rsnapshot_diff      /usr/bin/rsnapshot-diff

retain  daily   6
retain  weekly  4
retain  monthly 3

verbose         2
loglevel        3
logfile /var/log/rsnapshot.log
lockfile        /var/run/rsnapshot.pid

exclude         /home/foo/.cache
exclude         /home/foo/.thumbnails

backup  /home/foo/  localhost/

Check for proper syntax and run a snapshot test …

$ sudo rsnapshot configtest
$ sudo rsnapshot -t daily

If everything checks out OK run the daily snapshot (full backup on first run) …

$ sudo rsnapshot daily

Check the disk space used by rsnapshot by calling it with the du argument …

$ rsnapshot du 

Make automatic snapshots by modifying the sample cron file provided in /etc/cron.d/rsnapshot and running jobs as root. Example …

# m h  dom mon dow   command
10 3    * * *       root    /usr/bin/rsnapshot daily
10 2    * * 0       root    /usr/bin/rsnapshot weekly
10 1    1 * *       root    /usr/bin/rsnapshot monthly

These settings will run a daily snapshot everyday at 03:10, a weekly snapshot every Sunday at 02:10, and a monthly snapshot on the first of every month at 01:10. Make sure to stagger the backups so that rsnapshot does not get snarled trying to do overlapping backups at the same time.

Happy hacking!

Notes


  1. If using vim with the expandtab (replace tabs with whitespace) option, disable it temporarily when editing the config. [return]