In the past, many people have attempted to get Time Machine to back up to a linux server via netatalk. Usually this involved quite a bit of hackery, and was usually unreliable.
One of the reasons it was unreliable is because the netatalk share wouldn’t present itself as a time machine destination. You had to throw a switch on your OS X client to get it to use any network share. This didn’t always “just work”.
As of Netatalk 2.0.5, there is a “tm” option that can be used to present the share as a Time Machine destination. Problem is, most linux distros don’t have 2.0.5 in their repos yet, so you’ll have to compile it manually. I was able to do it on openSUSE 11.2 by configuring without the print option. For some reason, leaving that option off would fail, likely due to a dependency I didn’t care to troubleshoot. I wasn’t using print anyway.
So, when you compile, you’ll most likely have everything in /usr/local/netatalk unless you specified other options when you configured. In there you’ll have your AppleVolumes.default file that contains your shares, so you would add one like this:
The important part being at the option tm.
Restart netatalk: [sourcecode language=“bash”]sudo /etc/init.d/atalk restart[/sourcecode]
You should now be able to see the share in Time Machine Preferences without any trickery. The really helpful thing is, if you ever have to do a full restore, the share will also show up when booting to the OS X DVD.
So now if you have a unix box, you can start using it for Time Machine backups. If you’re planning one for some sort of NAS, I would actually recommend going with FreeNAS, assuming all you need is a NAS. FreeNAS will do all of this for you, and leverages the power of ZFS.