thank you for the info! Now I understand why someone needs something
like SANmp...
The problem with the recommended solution would be that if I had
a Xserve I would need too many dataports which wouldn't fit into it.
Now the direct DSS NAS solution via AFP works quite well, especially performance
at clients (80MB/sec with 1500 frames and tested with helios lan test)
The only problem is I have to give permissions manually (in DSS interface) if I want other users to work with the data they haven't produced - especially me as admin :-)
But in our edu enviroment this is ok (1 share per project; 1 user name per project team).