DOCUMENT:Q142037 11-JUN-2002 [sna] TITLE :SNA Server Fails to Release Memory in SNA TCP/IP Interface DLL PRODUCT :Microsoft SNA Server PROD/VER:WINDOWS:2.1,2.11 OPER/SYS: KEYWORDS:kbnetwork ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft SNA Server, versions 2.1, 2.11, on platform(s): - the operating system: Microsoft Windows NT ------------------------------------------------------------------------------- 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 SYMPTOMS ======== A Windows NT Server running SNA Server 2.11 slows down when running SNA Server clients that use TCP/IP. This problem occurs sporadically. CAUSE ===== An SNA Server Service internal trace shows that SNA Server TCP/IP asynchronous writes are not completing. These pending writes continue to consume system memory. The SNA Server client configured for TCP/IP may continuously attempt to open a session with the SNA Server. The SNA Server tries to send a response but the write never completes and is unable to release the i/o (input/output) buffer memory. RESOLUTION ========== SNAIP.DLL now aborts a connection if the connection has more than 100 pending writes queued. Every time a connection is aborted, an event 706 is logged in the application log: Event Id: 706 Description: Connection to client %2 has been aborted due to too many (%1) pending writes. Explanation SNA Server has aborted a TCP/IP connection because asynchronous writes queued on the connection have not completed. ACTION Provide network support personnel with the event log file(s) related to SNA, and SNA internal trace file(s). For information about SNA log and trace files, see the "Microsoft SNA Server Administration Guide." 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. You can configure the abort limit by adding the MaxPendingWrites registry parameter: 1. Go to the HKEY_LOCAL_MACHINE subtree under the following subkey: System\CurrentControlSet\Services\SnaBase\Parameters\SnaTcp If the SnaTcp subkey does not exist, it will need to be added it before going onto the next step. 2. Add the following information: Value Name: MaxPendingWrites Data Type: REG_DWORD Data: (decimal) where is by default 100 (decimal) with the updated SNAIP.DLL file (see below) installed. Microsoft has updated the following files to correct this problem: \SYSTEM\SNAIP.DLL \SYSTEM\SNAEVENT.DLL STATUS ====== Microsoft has confirmed this to be a problem in SNA Server for Windows NT. This problem was corrected in the latest SNA Server for Windows NT, 2.11 U.S. Service Pack. For information on obtaining the Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces): S E R V P A C K Additional query words: prodsna ====================================================================== Keywords : kbnetwork Technology : kbAudDeveloper kbSNAServSearch Version : WINDOWS:2.1,2.11 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.