Sorry, but I can not test behaviour on a System prior 10.6.6, because I don't have one. As I now realized, what this problem created, I now do the transfer from my old server to the new NAS not via rsync, I just make a copy via AFP.
Anyway, I was really surprised how easy it was, to make a share unusable!

I also read on the netatalk website about the CNID parameters, seems it is better to start with the DBD scheme, and only if there are any problems with many users, one may switch to CDB. See also: http://netatalk.sourceforge.net/2.1/...#CNID-backends