Based on this blogpost (DE) I set up a TimeMachine Backup Server on a Raspberry Pi 2. The V2 has enough processing power and RAM to serve this purpose well. The guide is well written, though some things need to be changed to make it work and run stable:
1) Use ext4 as filesystem for the backup disk. Sure you can install hfsutils, but Linux still does have problems with the Journaled HFS+. As the Mac communicates with the file system not directly, but over the server, its not necessary to give yourself a hard day.
2) When compiling Netatalk with the mentioned configuration, the MAKE process will fail. Configure must be updated to:
See: http://netatalk.sourceforge.net/wiki/index.php/Install_Netatalk_3.1.8_on_Debian_8_Jessie for more details.
3) Finally, in the start script I recommend using the drives UUID instead of /dev/sdx1
Many thanks to Simone > http://www.lisanet.de < for your support!