Average LDAP search latency has exceeded 50 milliseconds

[This topic is intended to address a specific issue called out by the Exchange Server Analyzer Tool. You should apply it only to systems that have had the Exchange Server Analyzer Tool run against them and are experiencing that specific issue. The Exchange Server Analyzer Tool, available as a free download, remotely collects configuration data from each server in the topology and automatically analyzes the data. The resulting report details important configuration issues, potential problems, and nondefault product settings. By following these recommendations, you can achieve better performance, scalability, reliability, and uptime. For more information about the tool or to download the latest versions, see "Microsoft Exchange Analyzers" at http://go.microsoft.com/fwlink/?linkid=34707.]  

Topic Last Modified: 2007-03-14

The Microsoft Exchange Analyzer tool includes a performance data collection engine that is used to query performance counter objects on computers that are running Exchange 2000 Server or Exchange Server 2003. The performance data collection engine collects data from the LDAP Search Time performance counter of the MSExchangeDSAccess Process performance object to analyze performance data.

The LDAP Search Time performance counter shows the time in milliseconds that it takes a Lightweight Directory Access Protocol (LDAP) search request to be fulfilled. The Exchange Analyzer retrieves a sample every 5 seconds for 5 minutes. The Exchange Analyzer then reports the maximum value for the performance counter during the collection interval. If the average value exceeds 50 milliseconds, the Exchange Analyzer displays a warning.

High LDAP search latencies can be caused by high remote procedure call (RPC) latencies and by increasing queues. High LDAP search latencies generally indicate one of the following problems:

  • A performance problem with the network connection to the domain controller.

  • Performance problems with the domain controller itself.

LDAP latencies are generally higher when users connect to domain controllers that are located in different physical sites. However, the recommended maximum latencies stated in this article should generally be followed.
If the domain controller that has logged this warning is located in a different physical site, you may be able to safely ignore this error if you can determine whether the domain controller that reports this warning is not used by the Exchange server. One way to determine whether a domain controller is used by Exchange is to increase diagnostic logging for the Topology component of the MSExchangeDSAccess service to Minimum. If you do not see MSExchangeDSAccess event ID event 2080, you can safely ignore this warning.

To resolve this warning, do the following:

  • Verify that all network connections to the domain controller are functional and support Internet Control Monitoring Protocol (ICMP) traffic.

  • Consider the best practices in the following articles:

    • For information about the LDAP Read Time performance counter and other counters you can use to troubleshoot Active Directory-bound problems, see the "Ruling Out Active Directory-Bound Problems" topic in Troubleshooting Microsoft Exchange Server Performance (http://go.microsoft.com/fwlink/?LinkId=47588). This article also includes information about how to improve Active Directory performance.

    • For more information about how to maximize Active Directory performance, see the "Active Directory Integration Tuning" topic in the Performance and Scalability Guide for Exchange Server 2003 (http://go.microsoft.com/fwlink/?LinkId=47576).

    • For information about making sure of high availability for your Active Directory servers, see the sections under Ensuring Reliable Access to Active Directory and Domain Name System in the "System-Level Fault Tolerant Measures" topic of the Exchange 2003 High Availability Guide (http://go.microsoft.com/fwlink/?LinkId=47571).

    • For information about network bandwidth considerations, see the Network Performance section of the "Understanding Exchange Performance" topic in the Performance and Scalability Guide for Exchange Server 2003 (http://go.microsoft.com/fwlink/?LinkId=47576).


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