I don't think you need any special agents for backing up clustered services with Netbackup. EMC Networker detects if a server is a cluster-node and forces you to buy expensive cluster-agents. Just make sure that you configure your backup policies in ...
I have seen this behavior when it comes to tape libaraies that are controlled via TCP/IP, such as ACS, DAS. Are you running the Netbackup Administration Console on a non-netbackup server (not a master- or mediaserver)? The problem was that the window...