Event 11 (1178) Causes SNA Server to Fail Abnormally

• Microsoft SNA Server for Windows NT, versions 2.0, 2.1, and 2.11

SYMPTOMS

When a Local APPC LU / Remote APPC LU partnership is defined in the SNA Server configuration file, SNA Server automatically negotiates the parallel session limit with the remote system when the connection that owns the Remote APPC LU is started. This negotiation occurs over an SNASVCMG mode session between these APPC LUs, using the Change Number of Sessions (CNOS) command as defined by IBM SNA architecture.

When a large number of APPC LUs are configured in SNA Server and SNA Server is started, SNA Server builds the SNASVCMG mode BIND messages and CNOS commands for all these LU/LU/mode partnerships and queues them internally until they can be processed. If there are so many partnerships that the internal SNA Server queue becomes exhausted, SNA Server logs the following event in the Windows NT application event log:

   Event 11 (1178) Initialization Failure
   1178 = Insufficient resources for automatic session limit negotiation

CAUSE

SNA Server interprets this condition as a fatal error, causing the SNA Server service (SNASERVR.EXE) to generate an SNA Server dump file.

RESOLUTION

You can correct this problem by installing an SNA Server 2.11 fix that is now available. This fix reduces the severity of the error so that SNA Server attempts to recover from the condition, rather than failing. Microsoft has updated the file SNASERVR.EXE to correct this problem.

To work around the problem without installing the fix:

• Reduce the number of APPC LU partnerships.

  Using the SNA Server Admin program, select each Local APPC LU, choose the Partners button, and delete any LU/LU/mode partnerships that are not being used. When the Enable Automatic Partnering checkbox is selected on an APPC LU or Mode, this can cause extra LU/LU partnerships that are not intended.

• Reduce the number of automatically activated sessions.

  Within the SNA Server APPC mode definition, the Automatic Activation Limit can be configured to automatically bind a specified number of LU6.2 sessions when the connection is started. Automatically starting an LU6.2 session ahead of time makes the session immediately available for an LU6.2 conversation. However, the overhead necessary to start an LU6.2 session is often negligible, so automatic session activation is often unnecessary.

  Reducing the automatic activation limit will reduce the number of BIND messages that SNA Server will queue internally.

• Defer CNOS processing until sessions are needed.

  The SNA Server service can be configured to defer the APPC LU CNOS processing until the LU sessions are actually requested by APPC applications. This feature can be enabled using the following registry entry:

        HKEY_LOCAL_MACHINE
        \SYSTEM\CurrentControlSet\Services\SnaServr\Parameters
        NOINITCNOS: REG_SZ: YES
  

  This setting will cause SNA Server to defer CNOS processing until an APPC application allocates a conversation over an APPC LU pair.

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