DOCUMENT:Q244396 11-JUN-2002 [winnt] TITLE :Determining if Full Syncs Are Caused By Wrapping the Change Log PRODUCT :Microsoft Windows NT PROD/VER:winnt:4.0 OPER/SYS: KEYWORDS: ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT Server version 4.0 ------------------------------------------------------------------------------- IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base: Q256986 Description of the Microsoft Windows Registry 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 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: 1. Start Registry Editor (Regedit.exe). 2. Locate the following registry key: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\NetLogon\Parameters 3. 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 : Technology : kbWinNTsearch kbWinNT400search kbWinNTSsearch kbWinNTS400search kbWinNTS400 Version : winnt:4.0 Issue type : kbinfo ============================================================================= THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY. Copyright Microsoft Corporation 2002.