XADM: Directory Service Stops Responding with Event ID 1186

The Directory service stops responding (hangs) and logs the following error message in the event log:

This behavior occurs if the directory replication agent (DRA) waits for more than 35 minutes for directory replication to complete within a site. This default timeout is normally sufficient and is exceeded only if a very large distribution list is being replicated or if there is limited usable bandwidth between the servers within the Exchange Server site.

To work around this behavior, restart the server that is experiencing the error, as well as the server that is specified in the text of the event. This works only if you find and resolve the underlying cause of the behavior (for example, saturated network links). The client may also need to look into breaking up large distribution lists.

If the problem persists after you restart both servers, you can change the behavior of the DRA by modifying the following registry values:

• Directory Replication Timeout
• Max Threads

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.

Directory Replication Timeout

You can change the default directory replication timeout value by adding the following key into the registry:

1. Start Registry Editor (Regedt32.exe).
2. Locate the following registry key:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MSExchangeDs\Parameters
3. On the Edit menu, click Add Value, and then add the following registry value:
   Value Name: Replicator async thread check (minutes)
   Data Type: REG_DWORD
   Value: 35 (Dec,default)
4. Quit Registry Editor.

NOTE: Increase this value in increments of 30 until you no longer receive the error message.

Max Threads

To increase the number of threads available for directory replication, adjust the following parameter:

1. Start Registry Editor (Regedt32.exe).
2. Locate the Max Threads value under the following key in the registry:
   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\ MSExchangeDS\Parameters\Max Threads (EXDS+NSP+DRA)
3. Click the Max Threads value.
4. On the Edit menu, click DWORD.
5. In the Data field, type 200 (Dec), and then click OK.
6. Quit Registry Editor.

This action increases the number of threads available from the default of 50 to 200. You may need to adjust this value for best results.