Adding LUs to TN3270 Admin Leads to Server Performance Problems

• Microsoft SNA Server for Windows NT versions 2.11 and 2.11 Service Pack 1

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.

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.

REFRENCE

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):

   ARTICLE-ID: Q137588
   TITLE     : TN3270 Service Will Not Start with a Large Config File

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.