FERPA alternative for German universities Is there anything similar to US Family Educational Rights and Privacy Act (FERPA) that is valid for German universities, or education system of Germany in general? 

I mostly concerned in preserving student's data in electronic form, e.g. am I allowed to share and collect assignments and test results, say, via Dropbox or own server? I hear in US the online data storage must be FERPA-compliant to preserve privacy in the first place, but I don't know what acts and policies govern this case in Germany.

I understand that many universities use own platforms, such as Moodle, adapted for the current needs, but what should I pay attention to if I want to go beyond?
According to the German Datenschutzgesetz and several state laws, it is forbidden to use private cloud services for storage of personal data. If you are at a university with access to ZENDAS, you can get a review of dropdox here.

A local server is fine, as long as you contact your local "Datenschutzbeauftragten" and announce the service. (S)he might have a form to fill in to evaluate the data security issues resulting from your installation. 

Tehre is no specific rule for universities, but the general rules from the German Datenschutzgesetz apply for universities as well. 

Platforms like moodle might breake existing German laws, it depends on the configuration of such systems (especially the tracing of activities is a problem).