Hi, We have 4 HUB/CAS servers running on Windows Server 2003. I have been asked to investigate whats involved in moving these servers to Windows Server 2008. 1. Is there an advantage from a performance point of view on moving these servers to Windows Server 2008? 2. I understand an upgrade of the OS is not an option. So, considering one of the HUB/CAS servers handles our activesync and is the first Exchange 2007 in the org, what guidelines are there in performing this upgrade/re-install of the 4 HUB/CAS servers to Windows Server 2008? Thanks in advance to all in advance.

Nothing to be gained performance wise. To move the roles around it is just a matter of building a new server with the required name, install Exchange with the correct roles. Then copy the configuration, SSL certificates etc across and redirect the firewall traffic. The first server isn't as critical as it was with Exchange 2003, so the server should remove correctly using add/remove programs. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

The best would be having 4 new servers on which install the CAS server role. Once you're done, decomissin the CAS role on w2003 Do the same with HT. In that way you would have a mixed environment cas=2010/ht=2007 for a while, and then cas/ht on 2010. If you will not do anything else, this upgrade is not worth in terms of performances. If you thing you will move to 2010 in the future, it makes sense. If yuo have performances issues at CAS/HT level, I would suggest to try addressing them by improving system resources (memory, paging etc.) on those servers end/or network bandwidth (it depends on what kind of perf issue you have) Also consider that with Ex2010 the CAS server is much more involved in the communication client/server, so if you have performances issues due to lack of system resources on your current CAS servers and move to Ex2010 (with the same servers), chances are you make things a bit worst Vincenzo MCTS, MCTIP Server 2008 | MCTS Exchange 2010 | WatchGuard Firewall Security Professional

Thanks for that. The issue we seem to be having is that Outlook 2007 is hanging from time to time with different people. Thats why we wondered if upgrading the OS on which the HUB/CAS Servers reside will improve the performance issues. Any thoughts?

I don't think upgrading the OS will have any effect on that issue with Outlook, other than the fact that you are rebuilding the system, which could mean updated drivers and a fresh start. Simon.Simon Butler, Exchange MVP Blog | Exchange Resources | In the UK? Hire Me.

Hi, It is not supported to do an in-place upgrade from Windows server 2003 to Windows server 2008 on a server where Exchange server 2007 is installed. And upgrading the OS on which the HUB/CAS resides will not improve the performance of outlook. I suggest you install Windows server 2008 on a computer that does not have Exchange installed, and then install Exchange 2007. Hope this helps. ThanksPlease 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.