Exchange 2003, Windows 2003 SP1, and PAE
Windows 2003 Service Pack 1 introduced a new feature called Data Execution Protection (DEP). The DEP feature essentially protects the operating system from applications that might run applications with buffer overruns. Some folks are finding that when they run the Exchange Best Practices Analyzer, it is reporting that PAE is enabled.
Exchange 2000/2003 is not compatible with DEP nor PAE. On some hardware, PAE (Physical Address Extensions) is automatically enabled. PAE allows the Windows Server operating system to use memory above 4GB. This can benefit some types of application servers such as SQL Server or Terminal Servers. This does not benefit an Exchange server.
In order to make sure that your Windows 2003 SP1 server is not using PAE or DEP, you should include the following lines in your BOOT.INI file:
The above options carry the Paul Bowden seal of approval. The /EXECUTE switch is not well documented, but it can be found in the Windows Internals 4th Edition Book. Of course, if the server has more than 1GB of physical memory, the BOOT.INI should include these options:
/3GB /USERVA=3030 /NOPAE /EXECUTE
KB 283037:Large memory support is available in Windows 2000 and Windows Server 2003
KB 817566: When starting with both the /PAE and the /3GB switches, the system may not start
KB 823440: Use of the /3GB switch in Exchange Server 2003 on a Windows Server 2003-based system
KB 328882: Exchange Memory Use and the /3GB Switch
KB 291988: A description of the 4 GB RAM Tuning feature and the Physical Address Extension switch
Newsgroup discussion and comments from Paul Bowden
KB 827281: CPU and memory scalability for Exchange Server 2003 and for Exchange 2000 Server