Using Linux computer as time capsule - possible but any experiences?
I've had experience with this, and it does work with some fiddling, but it doesn't "just work" in the mac sense. Every now and then, you'll find that you have to reconnect the volume, restart a daemon, or else face weird time machine errors.

If you're okay with being this "hands on", you'll need to install Netatalk (AFP daemon) and Avahi (Bonjour daemon) on your Linux machine, and set a defaults option on your mac to allow Time Machine to use network drives.

This is the guide I used for setting such a system up: http://techiezone.rottigni.net/2013/12/backup-your-mavericks-using-debian-linux-as-a-time-machine/

Make sure you keep a close eye on it for your first few weeks - nothing worse than backups that aren't actually backing up!