Optimizing memory usage in Exchange Server 2003

Improper use of Registry Editor can cause serious problems that may require you to reinstall your operating system. Microsoft is not guaranteed to resolve problems caused by improper use of Registry Editor. Using Registry Editor requires your own risk. This article describes the optimization of memory usage on a computer running Exchange Server 2003.

If you are running an Exchange Server 2003 server with more than 1 GB of physical memory installed, you must ensure that Exchange Server 2003 can use the memory efficiently.

Note: Exchange Server 2003 performs the optimal memory configuration check when the storage process is started. If the memory settings are not optimal, event 9665 will appear in Event Viewer. This message is displayed if any of the following conditions are true:

The server is running Microsoft Windows server, and the SystemPages value in the registry is out of the range 24000 to 31000.

The server has 1 GB or more of memory, and there is no/3GB switch.

The server is running Microsoft Windows Server 2003, has 1 GB or more memory, and the/3GB switch is set, but there is no/userva setting or the setting is beyond 3030 to 2970.

If you see this event, check the SystemPages and HeapDeCommitFreeBlockThreshold settings in the registry and check the/3GB switches and USERVA settings in the Boot.ini file. The following sections of this article contain recommended settings for all of these settings. If you want to turn off the memory configuration check, you can create the following registry key:

Hkey_local_machinesystemcurrentcontrolsetservicesmsexchangeisparameterssystem

Parameters: Suppress Memory Configuration Notification

Type: REG_DWORD

Set: 1

The memory configuration check does not occur on servers running Microsoft Small Business server. When the 9665 event is raised, the DWORD is written to the event log as additional data.

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Virtual address space Concept

The amount of memory that the information Store (Store.exe) process in Exchange Server 2003 can handle is limited, regardless of the hardware configuration, the number of databases on the server, and the number of users. This quantity is called a virtual address space. In most cases, this virtual address space used by the information store determines the overall performance and scalability of the Exchange Server 2003 mailbox server. For small and medium servers, Exchange Server 2003 automatically makes the balance the best state. However, for large servers, you may need to adjust some tuning parameters manually.

If your Exchange Server 2003 computer has 1 GB or more of memory installed, and if your computer is a host of mailboxes or public folders, be sure to add the/3GB switch to the Boot.ini file on the server. If there are no mailboxes or public folders (such as mail gateways) on the server, do not use the/3GB switch. By default, Microsoft Windows Advanced Server and Windows Server 2003 operating systems reserve 2 GB of virtual address space for kernel mode use and 2 GB for user mode. The virtual address space for a particular process is allocated at startup and increases with memory usage during the operation. Typically, a process actually uses less memory (working set) than the address space assigned to the process. On computers running Exchange Server 2003 that have 1GB or more of memory installed, you must modify Windows Advanced Server and the Windows Server 2003 operating system to have 3 GB of user mode Storage space available. You can do this by using the/3GB switch in the Boot.ini file.