I am getting some dodgy performance from OWA in a pure Exchange 2007 environment running on 2003 64bit OS. My setup is a front end CAS server that sits in a DMZ and a backend server that houses all the mailbox data. The front end server has the CAS,Edge Transport and Hub transport roles. The backend has all of the above plus mailbox storage role. I checked the performace counter MSExchange OWA\Average Response Time and it jumps all over the place from 1500 ms to 50ms. I ran perfmon on both boxes and noticed that the maibox server was running out of RAM so I added another 4 gig of ram. But am still seeing the same issue. The OWA requests sometimes works and at other times I get a 500 error request timed out with a no callstack available message. I am at my wits end on trying to figure out what the issue is. I looked at incoming bandwith thinking that may be a problem but have plenty. Can anyone point me in the right direction?? One other thing. This problem didn't start popping up until I installed KB940349 and Powershell 2.0. The KB I installed due to some VSS errors getting backups. Powershell install was so that I could have some expanded command sets to monitor my exchange environment.

Well, putting the CAS in the DMZ is defintely not supported. http://technet.microsoft.com/en-us/library/bb232184(EXCHG.80).aspx Installation of a Client Access server in a perimeter network is not supported. The Client Access server must be a member of an Active Directory directory service domain, and the Client Access server machine account must be a member of the Exchange Servers Active Directory security group. This security group has read and write access to all Exchange servers within your organization. Communications between the Client Access server and the Mailbox servers within the organization occurs over RPC. It is because of these requirements that installing a Client Access server in a perimeter network is not supported. Since this is Windows 2003, I would look at: http://blogs.technet.com/b/exchange/archive/2007/07/18/3403490.aspx Windows 2003 Scalable Networking pack and its possible effects on Exchange Also run ExBpa against the servers.

In 07 when I implemented this solution it was not in the docs that it wasn't supported. In either case it seems like the problem is firewall related. Sometimes the FW will drop RPC packets and sometimes it doesn't. Working with the vendor to figure out the problem. Thanks for the information though. When moving to 2010 I will take this under advisement.

Thanks for your understanding. Just for your reference, you may refer the following articles before you install Exchange 2010: Planning for Exchange 2010 http://technet.microsoft.com/en-us/library/aa995902.aspx Tools for Performance and Scalability Evaluation http://technet.microsoft.com/en-us/library/dd335108.aspx Exchange Pre-Deployment Analyzer http://www.microsoft.com/download/en/details.aspx?id=11636 Hope it is helpful. All the best Fiona