Hello, We currently have a CCR mailbox with 2 servers, and 3 hub/cas servers (each one has hub/cas roles installed), all running Exchange 2007 SP1. We want to upgrade to SP3 but our daily offline window is very short, is it possible to have some server roles running SP3 and others running SP1? For example, if we upgrade all three HUB/CAS servers to SP3 on day 1, Exchange will continue working normally even if it has the CCR mailbox (and each mbx server) with SP1 until on day 2 we upgrade the mailbox servers? Best regards

Yes, that should be fine. THe important part is that you upgrade in order : CAS, HUB , MBX last ( UM before MBX if you have it) You of course want the same SP level on the CCR servers, so once you apply SP3 to one node, do the other.

Thanks a lot for the quick reply Andy. I could not find any Technet article that solved my question (hence my question here in the forum), if you know any you are more than welcome post it here. Thanks!

Be sure to read the SP3 release notes: http://technet.microsoft.com/en-us/library/ff607233(EXCHG.80).aspx and how to upgrade CCR: http://technet.microsoft.com/en-us/library/bb676320(EXCHG.80).aspx http://technet.microsoft.com/en-us/library/bb676559(EXCHG.80).aspx

As an additional information, I would like to share you the following article: http://technet.microsoft.com/en-us/library/ee221147(EXCHG.80).aspx Thanks. NovakPlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.