====== Rsync ======

After you have setup [[readynas:ssh|ssh]] to work without passwords you can configure your server to perform incremental backups by getting [[wp>cron|cron]] to schedule [[wp>rsync|rsync]] tasks.

===== Basic Rsync Usage =====

Before scheduling ''rsync'' to run under ''cron'' its best first to work out how you want to run it.  A full description of how to use ''rsync'' is not appropriate here (see [[http://www.google.co.uk/search?q=rsync+tutorial|various tutorials]] instead), but lets back up our pictures folder (''~/pics/'') to the ReadyNAS.

<code bash>
$ rsync -av ~/pics readynas:~/.
</code>

Thats it, very simple.  I purposefully do not use the ''-z'' switch for compression as my pictures which are mainly JPEG are already in a compressed format so using compression gains nothing and actually increases the run-time slightly as the individual files require compressing and then decompressing at either end.  If this is the first time its been run then it will take a while to transfer all your data, but after that incremental back-ups will be very quick.

===== Scheduling Rsync =====

Now that you have a working ''rsync'' command you need to schedule it to run with ''cron''.  There are a number of different ''cron'' implementations, personally I use [[http://fcron.free.fr/|fcron]] because it works well running tasks that should have run when a system has been turned off.

==== Creating a script ====

You need to create a script which contains two commands, one to ensure your key, which is stored by [[readynas:ssh#keychain|keychain]] is loaded, because when you run a script its essentially a new login, and the second to actually run the above ''rsync'' command.  Create the file in ''~/bin''...

<code bash>
$ mkdir ~/bin
$ echo '#!/bin/bash' > ~/bin/rsync.pics
$ echo 'source ~/.keychain/$HOSTNAME-sh' >> ~/bin/rsync.pics
$ echo '/usr/bin/rsync -av ~/pics/*  readynas:~/pics/.' >> ~/bin/rsync.pics
$ chmod 0755 ~/bin/rsync.pics
</code>