Reserve increment size set

[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: 2007-01-30

The Microsoft® Exchange Server Analyzer Tool reads the following registry entry to determine whether a value for Reserve Increment KB has been set: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\MSExchangeIS\ParametersSystem

The Exchange Server Analyzer also queries the Active Directory® directory service to determine the value of the serialNumber attribute for all objects that have an object class of msExchExchangeServer. If the string value includes "Version 5.5," the computer is running Microsoft Exchange Server 5.5. If the string value includes "Version 6.0," the computer is running Microsoft Exchange 2000 Server. If the string value includes "Version 6.5," the computer is running Microsoft Exchange Server 2003. If the string value includes "Version 8.0," the computer is running Microsoft Exchange Server 2007.

If the Exchange Server Analyzer finds that the Reserve Increment KB registry value exists on a computer that is running Exchange Server 2003, a non-default configuration message is displayed.

The Reserve Increment KB registry value overrides the native memory heap value in Microsoft Windows®. Windows includes a process-wide heap manager that handles memory operations for all processes. Every time that a process instantiates, a default heap (called a process heap) is created for that process. Programs or modules loaded in the process can also create additional heaps if needed. The Microsoft Exchange Information Store service, Store.exe, is an example of a process that creates additional heaps when needed. By default Store.exe sets the initial memory that is reserved for heap space to 20 percent of physical RAM. The Reserve Increment KB value changes the initial memory reservation for heap to 10 percent of physical memory.

The Reserve Increment KB registry value is useful only in limited cases. Additionally, this value should only be set on the advice and direction of Microsoft Product Support Services. An incorrect setting or incorrect use of this value could result in decreased performance and accelerate fragmentation of virtual memory. If this value was set without consulting Microsoft Product Support Services, consider removing it using the following procedure.

To revert to the default configuration

  1. Open a registry editor, such as Regedit.exe or Regedt32.exe.

  2. Navigate to: HKLM\System\CurrentControlSet\Services\MSExchangeIS\ParametersSystem

  3. In the right pane, delete the Reserve Increment KB value.

  4. Close the registry editor and restart the Microsoft Exchange Information Store service for the change to take effect.

For more information about how to tune Exchange Server 2003, see the following Microsoft Knowledge Base articles: