5220 Appliance Master as FT Media Server

Hi

I undertsand that using a Master server as a FT media server is not recommended but I was interested to know if it is coded not to be configurable on a 5220 in that manner?

I have a two 5220 appliances - one is a Master\Media server and the other is a media server only (within a different NBU domain). I've set both appliances as FT media servers - that worked fine. But only the 5220 that is a media server works with a SAN client I have configured. The 5220 Master\Media server gives me an error (EMM Invalid ID) when I try to add the SAN client manually  - btw the SAN Client registered automatically on the other 5220.

Is this likely to be by design or an error that I can troubleshoot?

Both Appliances are running 2.5.2

many thanks