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XGEN: Optimizing Windows 2000 Active Directory Servers with Six or Eight Processors to Run with Exchange 2000

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Summary

Exchange 2000 Server is dependent on the Microsoft Windows 2000 Active Directory for both user and configuration information. Exchange 2000 predominantly uses Lightweight Directory Access Protocol (LDAP) to communicate to the domain controller and global catalog servers for this information. Exchange 2000 uses Active Directory very efficiently, but for many server and user actions a LDAP directory lookup is required.

When there are numerous Exchange 2000 servers in a Windows 2000 site, a very large LDAP load may be put on the Active Directory servers. By default, Active Directory is configured to have a MaxActiveQueries value of 20 (LDAP queries). This setting is the maximum number of pending LDAP queries that Active Directory can process.

If this limit is reached, Active Directory returns an error message "LDAP_ADMIN_LIMIT_EXCEEDED" and does not process further LDAP queries. A MaxActiveQueries value of 20 is generally sufficient for most Active Directory servers, but you may need to increase this value if you are running domain controllers on servers that have six or eight processors and you receive this error message.

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More information

You can increase the MaxActiveQueries value by using the Windows 2000 Ntdsutil.exe tool.

If you increase this setting, a little more memory is used in the Lsass.exe process in Active Directory, so do not increase this value any higher than necessary. The procedure to change this value is outlined in the following example: 
c:\>ntdsutil.exe
ntdsutil: Ldap policies
ldap policy: connections
server connections: Connect to server DCServer1
Binding to DCServer1 ...
Connected to DCServer1 using credentials of locally logged on user
server connections: q
ldap policy: Show Values
Policy                          Current(New)

MaxPoolThreads              8
MaxDatagramRecv             1024
MaxReceiveBuffer            10485760
InitRecvTimeout             120
MaxConnections              5000
MaxConnIdleTime             900
MaxActiveQueries            20
MaxPageSize                 1000
MaxQueryDuration            120
MaxTempTableSize            10000
MaxResultSetSize            262144
MaxNotificationPerConn      5
ldap policy: set MaxActiveQueries to 40
ldap policy: Commit Changes
ldap policy: Show Values

Policy                          Current(New)

MaxPoolThreads              8
MaxDatagramRecv             1024
MaxReceiveBuffer            10485760
InitRecvTimeout             120
MaxConnections              5000
MaxConnIdleTime             900
MaxActiveQueries            40
MaxPageSize                 1000
MaxQueryDuration            120
MaxTempTableSize            10000
MaxResultSetSize            262144
MaxNotificationPerConn      5

ldap policy: q
ntdsutil: q
Disconnecting from DCServer1
Active Directory picks up this change without restarting. In the preceding example, Active Directory processes no more than 40 LDAP queries at a time.

NOTE: This setting is global to all Active Directory servers in the forest. If you change this value on one Active Directory server, all the other domain controllers in the forest pick up the change as well.

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Keywords: KB271088, kbinfo

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Article Info
Article ID : 271088
Revision : 5
Created on : 2/21/2007
Published on : 2/21/2007
Exists online : False
Views : 272