DOCUMENT:Q197632 16-MAY-2002 [winnt] TITLE :Registry Hive Fragmentation Leads to Excessive Size PRODUCT :Microsoft Windows NT PROD/VER:winnt:4.0 OPER/SYS: KEYWORDS:kbWinNT400sp5fix ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Windows NT Workstation version 4.0 - Microsoft Windows NT Server version 4.0 - Microsoft Windows NT Server, Enterprise Edition version 4.0 ------------------------------------------------------------------------------- SYMPTOMS ======== Processes that use the registry to repeatedly modify the same values in small increments can cause excessive memory fragmentation in the corresponding registry hive. The sum of the fragmented cells can become so large that the hive size winds up many times larger than the sum of actual data in the hive. Eventually, the sum of the hive will exceed the Registry Size Limit (RSL), causing subsequent modifications to fail until the RSL is increased. As an example consider the SAM hive used to store Windows NT accounts. The SAM size frequently exceeds projected sizes due to the fact that it fragments the SAM hive when adding members to large groups. CAUSE ===== In the SAM example, when a user is added to a large group it causes the registry value for that group to be replaced and the old value added to a hash of free lists by size of allocation. The freed cell is coalesced with the nearest neighbor cell in memory, if it's a free cell, to create a slightly larger cell to add to the free lists. Over several additions, the free lists can contain several cells that are never used because they're too small. Over time the sum of the free cells become so large that the sum of the hives exceeds RSL. RESOLUTION ========== To resolve this problem, obtain the latest service pack for Windows NT 4.0 or the individual software update. For information on obtaining the latest service pack, please go to: - http://www.microsoft.com/Windows/ServicePacks/ -or- - Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack For information on obtaining the individual software update, contact Microsoft Product Support Services. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web: http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS STATUS ====== Microsoft has confirmed this to be a problem in Windows NT version 4.0. This problem was first corrected in Windows NT version 4.0 Service Pack 5. Additional query words: 4.00 ====================================================================== Keywords : kbWinNT400sp5fix Technology : kbWinNTsearch kbWinNTWsearch kbWinNTW400 kbWinNTW400search kbWinNT400search kbWinNTSsearch kbWinNTSEntSearch kbWinNTSEnt400 kbWinNTS400search kbWinNTS400 Version : winnt:4.0 Hardware : ALPHA x86 Issue type : kbbug Solution Type : kbfix ============================================================================= 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.