Microsoft KB Archive/251049

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Article ID: 251049

Article Last Modified on 10/26/2006


  • Microsoft Exchange Server 5.5 Standard Edition

This article was previously published under Q251049


If you define an AMAP (allocation map) attribute for export to a remote system, Lotus Notes directory synchronization (dirsync) may cause severe performance issues.


This issue can occur when you define an AMAP attribute for export to a remote system, because the process defines the attribute for export by default, and there is no corresponding mapping rule for import.

During import, the Exchange Server (Dxamex) and Lotus Notes (Dxanotes) processes compare the attribute import value (usually a null value, because there is no import mapping rule) against an internal system value (which is most likely not a null value). Because the two values are different, the Directory Exchange Agent (DXA) also tries to update the target entry, even if none of the attributes have been updated at the source, because some of the export-only attributes are included as part of the import. This behavior causes a severe performance hit, because a very full load causes every entry in the system to be refreshed.


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 Lotus Notes directory synchronization (dirsync) process now allows an AMAP attribute definition (an AMAP column specifier) that designates an attribute either for export only, or for import and export.


To work around this issue, modify the mapping rules.


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.


Before this attribute definition capability was added, there was no way to specify a particular attribute as "Read Only."

Additional query words: readonly attribute reload notes dirsync

Keywords: kbbug kbexchange550presp4fix kbexchange550sp4fix kbfix kbqfe KB251049