API or Message Tracing May Cause SNA Server Process to Hang

• Microsoft SNA Server, versions 3.0, 3.0 SP1, 3.0 SP2, and 4.0

SYMPTOMS

When you do API or Message tracing on an SNA Server process (such as the Shared Folders Gateway Service), the process may hang in certain conditions, causing other problems such as a loss of network connectivity to the SNA Server computer.

The SNA Server service or Win32 SNA application may hang unexpectedly if Message tracing or API tracing is enabled. This problem does not affect internal tracing. When the process hangs, the SNA session status may continue to indicate an active status and the SNA data flow on the session will be suspended.

This problem can cause the SNA Server service to hang while message tracing is enabled. The types of message tracing that can cause this problem to occur are Server Data Link Control (DLC), LU 6.2, and 3270. An SNA Server link service may also hang when enabling DLC message traces. If this occurs, the SNA Server service or SNA link service will become unresponsive (for example, existing clients will lose their sessions), and any attempt to stop the SNA Server service will show a perpetual "Stopping" status.

This problem can also cause a Win32 SNA application to hang while API or message tracing is enabled. If this occurs, the SNA Application traces will not have been flushed to disk; therefore, the API or message traces will not indicate the last API call issued by the application. The trace file size may have reached its maximum configured size when this problem occurs. SNA Application full internal traces will indicate that it is still responding to SNA Server "keepalive" messages.

This problem may occur more frequently when a small trace file size is configured, or if there is a large amount of message activity that causes the trace files to fill quickly.

CAUSE

The tracing mechanism within SNA Server is not properly flushing the trace statements to the file.

STATUS

Microsoft has confirmed this to be a problem in SNA Server 3.0 (all service packs) and SNA Server 4.0. A supported fix is now available for SNA Server 4.0, but has not been fully regression-tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Technical Support for more information.

MORE INFORMATION

With this update applied, the Trace utility functions correctly.

Version           : WINDOWS:3.0,3.0SP1,3.0SP2,4.0
Platform          : WINDOWS
Issue type        : kbbug
Solution Type     : kbfix