I have 2 CAS, 2 HUB, and 2 (2 Node) CCR clusters in my Exchange 2007 environment. We are currently on Exchange 2007 SP3. I have to upgrade all server to SP3 RU1. My process will be to upgrade the 2 CAS servers, then the 2 HUB servers, and finially the 2 CCR clusers. On the CCR clusters, I install the RU on the passive node, failover to the node with the RU1 on it and then install RU1 on the onther node, is that correct? I dont have to do andthing on the CMS, correct? Anything else to be aware of?

Your thought process on order is correct. Here is a step-by-step on updating the CCR cluster: http://technet.microsoft.com/en-us/library/bb885047(EXCHG.80).aspx Tim Harrington - Catapult Systems - http://HowDoUC.blogspot.com

Agreed, Consider RU installation as a patch installation on CCR Box,s. Only you have to upgrade CMS in case of SP installation. Anil