I have recently contacted the Netatalk developers mailing list requesting they add support for the FPSyncForc command in order to finally achieve 100% TimeMachine compatibility.
You can see the exchange here :
Frank Lahm took the original patch for FPSyncFork from Bolke de Bruin and committed it to the Netatalk CVS as can be seen here :
I make this request as a bug report and not as a feature request as i consider this a bug in Netatalk and not as a new feature.
Volker, can you add this new revision of Netatalk that includes FPSyncFork support to one of your next nightly builds and i will test it to see if TimeMachine will finally complete the initial sparsebundle creation on the AFP volume on FreeNAS. This is pretty much untested right now but the patch looks good and i'm eager to get TimeMachine working on FreeNAS :)
Thanks alot for your help on this,