So I built an Exchange 2007 CCR scenario. I have4 servers: domain controller, nodeA, nodeB, and a standalone server with the transport hub and client access roles installed. Microsoft proclaims there is no single point of failure in a CCR scenario...if you shutdown the transport hub server you get no mail???

Hi Zemi, What we're saying is that CCR is a mailbox HA solution with no single point of failure. But you still need to use other strategies to achieve HA for the other Exchange server roles that you'll have in your environment (e.g., CAS, Hub, etc.). You can find the HA strategies for the other server roles documented at http://www.microsoft.com/technet/prodtechnol/exchange/e2k7help/d2efb6f9-f70a-4f96-9f8d-f7aad6ae83d7.mspx. All messages will travel through a Hub Transport server at some point. So to ensure you have HA for transport, you'll want to make sure that you have multiple Hub Transport servers in each AD Site. There is built-in resiliency and HA logic in the Hub Transport role, so you don't need to use load balancing, RR DNS, or other techniques to achieve HA. Hope this helps.

thx

This answers part of the question but what about the effect on the shared quorum storage held on the primary hub transport server? Can you explain how we would make that redundant? Should we use some sort of shared storage for that system?

The "shared quorum storage held on the primary hub transport server" does not represent a single-point of failure (SPOF). If the Majority Node Set with File Share Witness quorum (Windows 2003) or the Node and Share Majority quorum (Windows 2008) on the primary Hub Transport server goes down, the active CCR node will still work. If however in this scenario, in addition the active CCR node goes down, no fail-over will occur. You could argue that this is double-point of failure. But you should be prepared for this situation:New File Share Witness and Force Quorum Guidance for Exchange 2007 Clustershttp://msexchangeteam.com/archive/2008/04/03/448615.aspxAs to "some sort of shared storage for that system", there have been some recommendation on placing the quorum on a clustered file server. But the shared storage ('share nothing') still represents a SPOF.Jon-Alfred Smith MCTS: Messaging MCSE: S+M