Set up Firebird with shared storage?
If you have more than one cpu on the server you need to use Super Classic 

http://www.firebirdsql.org/file/documentation/reference_manuals/user_manuals/html/qsg25-classic-or-super.html

Also we need more info on the arhitecture that you want to create 
I would avoid point 2 (firebird doesn't work on shared nfs)