Microsoft KB Archive/311438

= SNA Applications &quot;Hang&quot; with Event 556 =

Article ID: 311438

Article Last Modified on 2/22/2007

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APPLIES TO


 * Microsoft Host Integration Server 2000 Standard Edition
 * Microsoft SNA Server 4.0

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This article was previously published under Q311438



SYMPTOMS
SNA applications that are running on an SNA Client may stop responding (&quot;hang&quot;), 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.



SNA Server 4.0
A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem. This fix may receive additional testing. 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 hotfix.

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, visit the following Microsoft Web site:

http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The typical 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:

NOTE: Because of file dependencies, the most recent fix that contains the preceding files may also contain additional files.

Host Integration Server 2000
To resolve this problem, obtain the latest service pack for Host Integration Server 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

328152 How to Obtain the Latest Host Integration Server 2000 Service Pack



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.



SNA Server 4.0
Microsoft has confirmed that this is a problem in Microsoft SNA Server version 4.0.

Host Integration Server 2000
Microsoft has confirmed that this is a problem in Microsoft Host Integration Server 2000. This problem was first corrected in Host Integration Server 2000 Service Pack 1.



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: HIS 2000

Keywords: kbbug kbfix kbhostintegserv2000presp1fix kbhostintegserv2000sp1fix KB311438

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