DOCUMENT:Q176520  11-SEP-1999  [exchange]
TITLE   :XADM: Limiting Memory Usage of Exchange Server
PRODUCT :Microsoft Exchange
PROD/VER:winnt:4.0,5.0,5.5
OPER/SYS:
KEYWORDS:

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft Exchange Server, versions 4.0, 5.0, 5.5 
-------------------------------------------------------------------------------

SUMMARY
=======

You may use the Microsoft Exchange Performance Optimizer to limit the amount of
memory that Microsoft Exchange Server uses, but you cannot manually set this
value within the registry of an Exchange Server computer.

Microsoft Exchange Performance Optimizer includes an option to limit the amount
of memory that Microsoft Exchange Server has access to. By default this value is
set to zero, which allows Microsoft Exchange Server access to all of the
available RAM on the server.

If you want to limit the amount of memory that Microsoft Exchange Server can
access, you can run Microsoft Exchange Performance Optimizer and enter the
amount of memory you want the Exchange Server computer to use. The value should
be 24 MB or more. 32 MB or more is recommended.

MORE INFORMATION
================

The size of the Microsoft Exchange Server memory cache is adjusted automatically
when you use the Performance Optimizer. By default, Microsoft Exchange Server
uses all of the physical memory available. If you run other programs on your
servers, you can restrict the amount of memory used by Microsoft Exchange
Server.

When you run the Performance Optimizer, it analyzes the servers resources and
configures the server as follows:

The Performance Optimizer detects the amount of physical memory in the server and
calculates the size of the caches for the directory and the information store
based on the information you provide about how the server will be used.

The default values for the directory and information store caches are appropriate
for most installations. Although larger caches may provide better performance in
some circumstances, performance depends on the amount of physical memory
available.

Based on the values computed by Performance Optimizer, changes are made to the
registry; these values cannot be manually computed and modified in the registry.

Additional query words:

======================================================================
Keywords          :  
Technology        : kbExchangeSearch kbExchange500 kbExchange550 kbExchange400 kbZNotKeyword2
Version           : winnt:4.0,5.0,5.5
Issue type        : kbinfo

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 1999.