This Exchange server has more than 4 GB of memory

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at]  

Topic Last Modified: 2006-06-20

The Microsoft® Exchange Server Analyzer Tool queries the Win32_ComputerSystem Microsoft Windows® Management Instrumentation (WMI) class to determine the value for the TotalPhysicalMemory key for each Exchange Server computer.

If the Exchange Server Analyzer finds the value for TotalPhysicalMemory greater than 4294967296 but less than 6442450944, a warning is displayed.

If the Exchange Server Analyzer finds that the value for TotalPhysicalMemory is greater than 6442450944, an error is displayed.

A value for TotalPhysicalMemory greater than 4294967296 indicates that the Exchange Server computer has more than 4 gigabytes (GB) of memory installed while a value for TotalPhysicalMemory greater than 6442450944 indicates that the Exchange Server computer has more than 6 GB of memory installed. On a computer with 4 GB or more of physical memory, Exchange Server will not use any more than 3 GB. Therefore, if the computer is dedicated to running Exchange Server only, there is no benefit to installing more than 4 GB of memory.

More importantly, the more physical RAM that is present, the more operating system kernel address entries are needed to perform the necessary virtual to physical mapping. This reduces both the free system page table entries (PTEs) and the paged pool memory available to the system which could cause instability.

As an example, a computer with 8 GB of physical RAM will have 3,000 fewer free system page table entries (PTEs) and a 30 MB reduction in the maximum paged pool size than a computer with only 4 GB of physical RAM.

It is recommended that you follow one of these two solutions:

  • Reduce the amount of memory in the system to 4 GB

  • Set the BurnMemory parameter in the Boot.ini file to reduce the physical memory to 4 GB, as described later in this article.

Additionally, if you are running multiple applications that require the extra memory, you can run a Windows hotfix that will help prevent Exchange information store failures that could occur when there is more than 4 GB of RAM available. Note that the recommended best practice is to dedicate a computer to run Exchange Server only. For details about the hotfix, see the Microsoft Knowledge Base article 834628, "Data is corrupted when PAE is enabled on a Windows Server 2003-based computer" (

To correct this warning

  1. In Windows Explorer, navigate to the system partition.

  2. If you are unable to see the boot.ini file, it could be because the Folder Options are set to Hide protected operating system files. If this is the case, in Windows Explorer, click Tools, Folder Options, and then click the View tab. Clear the Hide protected operating system files (Recommended) check box. When prompted with the warning box, click Yes.

  3. Once the boot.ini file is visible in Explorer, right-click the file, click Open With, and choose Notepad to open the file.

  4. In the [Operating Systems] section, add the following switch to the startup line: /BURNMEMORY=<Value in MB>

    For example:

    If there is 6GB of physical memory installed, use /BURNMEMORY=2048 to reduce the available memory to 4GB. If there is 8GB of physical memory installed, use /BURNMEMORY=4096.

  5. Save the changes and close Notepad.

  6. Reboot the Exchange Server computer for the change to take effect.

For more information about the parameters that can be used in the Boot.ini file, see the following Microsoft Knowledge Base articles: