Robert’s Rules of Exchange: Multi-Role Servers

@Jeremy Hagan - That should work, but as you note it would require you doing the work to make sure that the script worked, etc.  If you needed a better than that 5 minute RTO, or if you needed to make sure that the load was actually balanced across the two CAS servers (smaller orgs won't need this), then you can't make this work, and this is the reason that it isn't one of our recommended solutions to the problem for our enterprise customers.  But, if it works for you, then go for it.

@XMichaeL - We have changed our guidance from "core count" to "socket count".  Read the table carefully on this page:  http://technet.microsoft.com/en-us/library/dd346699.aspx   What we say is that we recommend a maximum of 2 populated processor sockets for any single role server or a CAS/HT combined role server, and a maximum of 4 populated processor sockets for a mulit-role server (with CAS/HT/MBX all on the same server).  That gives a "theoretical" limit of 12 or 24 cores in the table if you have 6-core processors, but that doesn't mean that the 8-core processors are not supported or recommended.  Drive your maximums based on the number of sockets, not cores!