Microsoft KB Archive/249148

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Article ID: 249148

Article Last Modified on 10/26/2006


  • Microsoft Exchange Server 5.5 Service Pack 3

This article was previously published under Q249148


If you monitor the Exchange Server computer by using Performance Monitor, you find that many handles leaked after an online backup.


Several registry keys are opened during an online backup. Some of them come from the Mdbrest.dll file. After the query, the keys are not closed. They remain open for later use for performance reasons. But if the Mdbrest.dll has been relocated because of a memory address collision, those keys are not closed. They are reopened, and the previous handles leak when they are queried again.


To resolve this problem, obtain the latest service pack for Exchange Server 5.5. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

191014 XGEN: How to Obtain the latest Exchange Server 5.5 Service Pack

The following files are available for download from the Microsoft Download Center:

For additional information about how to download Microsoft Support files, click the following article number to view the article in the Microsoft Knowledge Base:

119591 How to Obtain Microsoft Support Files from Online Services

Microsoft scanned this file for viruses. Microsoft used the most current virus-detection software that was available on the date that the file was posted. The file is stored on security-enhanced servers that help to prevent any unauthorized changes to the file.


Microsoft has confirmed that this is a problem in Microsoft Exchange Server version 5.5. This problem was first corrected in Exchange Server 5.5 Service Pack 4.


If you use CDB to attach to the Mad.exe file, the following information is displayed:

LDR: Automatic DLL relocation in Mad.exe
LDR: Dll mdbrest.dll base 004b0000 relocated due to collision with Dynamically Allocated Memory
CDB ModLoad: 0b950000 0b982000 Mdbrest.dll
CDB ModLoad: 6fcc0000 6fcd4000 C:\Exchsrvr\Bin\Netif.dll
CDB ModLoad: 6fcb0000 6fcb8000 C:\Exchsrvr\Bin\Isatq.dll

If you use the Oh.exe file to check the handles that are held by the Mad.exe file, you find that the leaked handles are from the following key:


The fix closes all such keys when the .dll file is detached.

Keywords: kbbug kbexchange550presp4fix kbexchange550sp4fix kbfix kbgraphxlinkcritical kbqfe KB249148