As I understand it you can use quite a variety of storage arrays behind a DataDomain gateway. The N-Series should be supported, but you'd have to check DataDomain for exact revisions and details of this. Sometimes vendors certify the NetApp equivelant but not the N-Series, so find the NetApp equivelant and it should follow suit.
Why would you want to use A-SIS and ProtecTIER together? I'm not sure if it technically wouldn't work, but there would be no benefit. In fact you may find that you end up with more space usage. A strange consequence of running A-SIS on a volume that won't dedupe very well. The same thing happens if you try to RAR a ZIP file for instance, the resulting file will often be bigger as it still has to write all the headers and extra info in.
