Microsoft KB Archive/159981

= Adding LUs to TN3270 Admin Leads to Server Performance Problems =

Article ID: 159981

Article Last Modified on 11/19/2003

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APPLIES TO


 * Microsoft SNA Server 3.0, when used with:
 * Microsoft Windows NT 4.0
 * Microsoft SNA Server 2.11 Service Pack 1, when used with:
 * Microsoft Windows NT 4.0

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This article was previously published under Q159981





SYMPTOMS
When using the SNA Server 2.11 (or SP1) TN3270 Server with a large number of LUs (over 250), the following problems may occur when running TN3270 Administrator program to add new LUs to the configuration:
 * Windows NT may become very slow or unresponsive.
 * Performance Monitor will show the CPU utilization at 100 percent.
 * Existing TN3270 users who are connecting through the TN3270 Server may stop receiving responses from the host, or may lose their TN session.

NOTE: In addition, if SNA Server 2.11 is being used, the TN3270 service fails to start when using a large TN3270 configuration file. This particular problem was fixed in SNA Server 2.11 Service Pack 1.



CAUSE
The TN3270 Admin program does not efficiently handle configurations which involve a large number of LUA LUs.



RESOLUTION
Under SNA Server 2.11 or SP1, the TN3270 Server configuration file size could be reduced to work around the problem. This can be accomplished by assigning users to pools of LUA LUs, rather than configuring a large number of unique LUA LUs. To create pools of LUA Lus:
 * 1) Use the SNA Server Administrator program LU Pools window to group LUA LUs together.
 * 2) Assign instances of the LUA pools to TCP/IP users within the TN3270 Administrator program.

If specific LUs must be assigned, requiring a large number of LUA LUs to be defined, the only workaround is to make TN3270 Server configuration changes after hours. Otherwise, there is no resolution using SNA Server 2.11 or SP1 except to upgrade to SNA Server 3.0. Under SNA Server 3.0, the TN3270 Server administration is integrated with the new SNA Server Manager interface, so the TN3270 Administrator tool is no longer used.



STATUS
Microsoft has confirmed this to be a problem in SNA Server version 2.11 or 2.11 Service Pack 1. See the Resolution section above for possible workarounds. This problem is solved in SNA Server 3.0.



MORE INFORMATION
See the following Microsoft Knowledge Base article for more information on the TN3270 service failing to start when using a large TN3270 configuration file (this problem occurs only SNA Server 2.11, not Service Pack 1):

137588 TN3270 Service Will Not Start with a Large Config File

Additional query words: prodsna

Keywords: kbbug kbfix kbnetwork KB159981

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