Microsoft KB Archive/288753

= XCCC: Limiting the Number of OMSG Objects Opened by Client on Server =

PSS ID Number: 288753

Article Last Modified on 6/5/2003

-

The information in this article applies to:


 * Microsoft Exchange 2000 Server

-



This article was previously published under Q288753



IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry



SYMPTOMS
Microsoft Outlook 2002 may recursively open a contact folder thousands of times, until either the server crashes or a stack fault occurs in the client.



CAUSE
This problem occurs because the server is vulnerable to certain client problems, and the administrator cannot protect the server from these client problems to keep the server running.



RESOLUTION
To resolve this problem, obtain the latest service pack for Microsoft Exchange 2000 Server. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

301378 XGEN: How to Obtain the Latest Exchange 2000 Server Service Pack

The English version of this fix should have the following file attributes or later:

Component: Information Store



STATUS
Microsoft has confirmed that this is a problem in Microsoft Exchange 2000 Server. This problem was first corrected in Microsoft Exchange 2000 Server Service Pack 1.



MORE INFORMATION
This fix provides a mechanism that you can use to limit the number of OMSG objects that a client can open during any particular logon session. You can set this limit dynamically; the default setting is unlimited.

Exchange 2000 maintains a count of OMSG objects for each logon session. After you apply this fix, you can change a registry setting to limit this number. If you set the registry value to any value other than zero, and the current OMSG object count for a logon session is equal to or greater than the registry value, when a client attempts to create another OMSG object, the creation operation fails with ecNotSupported. This causes problems for the client, but prevents the client from using up all of the memory in the address space.

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

To edit the registry to limit the number of OMSG objects that a client can open during any particular logon session:  Start Registry Editor (Regedt32.exe). Locate the following key in the registry:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeIS\ParametersSystem

 On the Edit menu, click Add Value, and then add the following registry value:

Value Name: MaxOpenMessagesPerLogon

Data Type: REG_DWORD

Radix: Decimal

Value: Set this value to the maximum number of messages that you want each client logon session to be able to open simultaneously. 1,000 is an appropriate value; a value of 1,000 allows each client to use approximately 4 to 6 megabytes (MBs) of memory.

 Quit Registry Editor.</ol>

Keywords: kbbug kbExchange2000preSP1fix kbfix kbQFE KB288753

Technology: kbExchange2000Search kbExchange2000Serv kbExchange2000ServSearch kbExchangeSearch

-

[mailto:TECHNET@MICROSOFT.COM Send feedback to Microsoft]

© 2004 Microsoft Corporation. All rights reserved.