Microsoft KB Archive/163073

= Backup Config. Server May Not Always Read Local Config. File =

Article ID: 163073

Article Last Modified on 11/26/2003

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APPLIES TO


 * Microsoft SNA Server 2.0
 * Microsoft SNA Server 2.1
 * Microsoft SNA Server 3.0
 * Microsoft SNA Server 2.11 Service Pack 1

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This article was previously published under Q163073





SYMPTOMS
If the SNA Server service is configured to start automatically on a backup configuration server and the SnaBase broadcast from the primary configuration server has not yet been received, SNA Server may read its configuration entries from another backup server's configuration file instead of the local Com.cfg file. This will likely cause no problems, but it may be inefficient.

If the SNA Server service encounters a network error while reading its configuration file entries from another backup server or from the primary configuration server, the following error occurs (though the Windows NT Server return code may vary):

Event ID: 351

Source: SNA Server

Description: Error trying to read from \\server\COMCFG\COM.CFG (rc=995)

Windows NT Server return code 995 = ERROR_IO_INCOMPLETE.

This may indicate a problem with the underlying network. The above error occurred at a site where the primary configuration server was located across an IP router from the SNA Server. The IP router was acting as a "black hole router," which was causing the network session to fail abnormally. For more information on "black hole routers," see the following article in the Microsoft Knowledge Base:

159211 Diagnoses and Treatment of Black Hole Routers



CAUSE
When the SnaBase service starts on SNA Server, it listens for "service table" broadcast announcements from other SnaBase services running on other computers running SNA Server in the SNA subdomain. This broadcast message indicates the SNA Server services running on the server, the server's role in the SNA domain, and other attributes.

The SnaBase service (on backup and member configuration servers) keeps track of the "preferred" location for the SNA Server configuration file for the subdomain. When the SNA Server service starts, it reads its configuration entries from the configuration file located on the "preferred" server.

If a broadcast is received from the primary configuration server, then the primary server is always the preferred server. However, if the SnaBase has not yet heard from the primary configuration server, a remote backup server is chosen as the preferred server, instead of the local backup configuration file.



RESOLUTION
A backup configuration server now prioritizes the local Com.cfg file ahead of other backup configuration servers, if the primary configuration server announcement has not been received or if its SnaBase is not running.



STATUS
Microsoft has confirmed this to be a problem in Microsoft SNA Server versions 2.0, 2.1, 2.11, and 2.11 Service Pack 1. This problem was corrected in the latest SNA Server version 2.11 U.S. Service Pack. For information on obtaining this 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 kbbug2.00

Keywords: KB163073

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