DOCUMENT:Q311438 08-MAY-2002 [sna] TITLE :SNA Applications "Hang" with Event 556 PRODUCT :Microsoft SNA Server PROD/VER::4.0 OPER/SYS: KEYWORDS:kbDSupport sna4 kbsna400sp1 kbsna400sp2 kbsna400sp3 kbhis2000 kbhis2000bug kbsna400sp4 ====================================================================== ------------------------------------------------------------------------------- The information in this article applies to: - Microsoft Host Integration Server 2000 - Microsoft SNA Server, version 4.0 ------------------------------------------------------------------------------- SYMPTOMS ======== SNA applications that are running on an SNA Client may stop responding ("hang"), when one of the applications requests a logical unit (LU). The following event may be logged in the Application Event Log when this occurs: Event ID: 556 Description: A system error occurred while making a pipe connection, rc = This problem occurs when there are multiple SNA applications running on the same system that repeatedly load and unload any of the SNA API (RUI, SLI, APPC, or CPI-C) dynamic link libraries (DLLs). CAUSE ===== An internal resource that keeps track of SnaBase's active RamPipe connections can exceed its maximum value under certain circumstances, which causes the problem. RESOLUTION ========== SNA Server 4.0 -------------- A supported fix is now available from Microsoft, but it is only intended to correct the problem described in this article and should be applied only to systems experiencing this specific problem. This fix may receive additional testing at a later time, to further ensure product quality. Therefore, if you are not severely affected by this problem, Microsoft recommends that you wait for the next Microsoft SNA Server version 4.0 service pack that contains this fix. To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, please go to the following address on the World Wide Web: http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS NOTE: In special cases, charges that are normally incurred for support calls may be canceled, if a Microsoft Support Professional determines that a specific update will resolve your problem. Normal support costs will apply to additional support questions and issues that do not qualify for the specific update in question. The English version of this fix should have the following file attributes or later: +---------------------------------+ | File name | Date | Time | +---------------------------------+ | Snadmod.dll | 3/26/2001 | 11:28 | +---------------------------------+ NOTE: Because of file dependencies, the most recent fix that contains the above files may also contain additional files. Host Integration Server 2000 ---------------------------- No fix is available for this problem in Host Integration Server 2000 at this time. WORKAROUND ========== To avoid this problem, keep the number of concurrent SNA applications below 15 or rewrite the applications to avoid repeatedly loading and unloading the SNA API DLLs. STATUS ====== SNA Server 4.0 Microsoft has confirmed this to be a problem in Microsoft SNA Server version 4.0. Host Integration Server 2000 Microsoft has confirmed this to be a problem in Microsoft Host Integration Server 2000. MORE INFORMATION ================ SnaBase maintains an internal table called the LPd table to track client server connections. This table can contain up to 255 entries. If there are multiple processes that repeatedly load and unload any of the SNA API DLLs, each process may consume as many SnaBase LPd records as there are processes. For example, if you have 30 processes, the total number of allocated LPds can be up to 30*30, which is greater than 255. How many records each process actually uses depends on the sequence in which they load/unload the SNA API DLLs. If the timing is correct each process may only use one record; if the timing is bad, each process can consume a lot more. There must least 15 local SNA processes in order for this problem to occur. Additional query words: ====================================================================== Keywords : kbDSupport sna4 kbsna400sp1 kbsna400sp2 kbsna400sp3 kbhis2000 kbhis2000bug kbsna400sp4 Technology : kbAudDeveloper kbSNAServSearch kbHostIntegServ2000 kbSNAServ400 Version : :4.0 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. 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