How to Determine if Full Synchronizations Are Caused By Wrapping the Change Log

ID: Q244396

The information in this article applies to:

Microsoft Windows NT Server version 4.0

IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information about how to do this, view the "Restoring the Registry" Help topic in Regedit.exe or the "Restoring a Registry Key" Help topic in Regedt32.exe.

SUMMARY

There may be situations where you want to determine why backup domain controllers (BDCs) request full synchronizations.

MORE INFORMATION

Full synchronizations can be caused by several things:

Using the Portuas tool

Using the Nltest tool

Using the net accounts /sync command

Wrapping the change log

The only item above that can occur by itself is wrapping the change log. You can use the checked build of the Netlogon.dll file to determine if the change log was wrapped.

To log enough information to determine if the change log was wrapped, set the following parameter in the registry:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\Netlogon\Parameters

Value Name: DBFlag
Data Type: REG_SZ
String: 0x20000108 (hex)

The following lines show that a full synchronization was caused by wrapping the change log:


10/20 16:53:53 [SYNC] NetrDatabaseDeltas: SAM partial sync called by <BDC_Name> SerialNumber:0 7c7d.

10/20 16:53:53 [CRITICAL] NetrDatabaseDeltas: delta not found in cache, returning full required.

The first line represents a particular BDC requesting all new changes. In this example, the BDC had changes up to 0 7c7d, or the first 31,869 changes to the Security Accounts Manager (SAM).

The second line shows that the requested delta is no longer in the change log. The primary domain controller (PDC) ignores the partial request and tells that BDC to request a full synchronization.

You can change the size of the change log from 64 KB to 4.19 MB. Each change averages 32 bytes, so the change log can store approximately 2,000-130,000 changes.

To change the size of the change log:

Start Registry Editor (Regedit.exe).

Locate the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NetLogon\Parameters

On the Edit menu, click Add Value, and add the following value:

Value Name: ChangeLogSize
Data Type: REG_DWORD
String: 0x400000 (hex)

Additional query words: synchronization 5713

Keywords :
Version : winnt:4.0
Platform : winnt
Issue type : kbinfo