DOCUMENT:Q159981  13-JUN-2001  [sna]
TITLE   :Adding LUs to TN3270 Admin Leads to Server Performance Problems
PRODUCT :Microsoft SNA Server
PROD/VER:WINDOWS:2.11,2.11 SP1
OPER/SYS:
KEYWORDS:kbnetwork

======================================================================
-------------------------------------------------------------------------------
The information in this article applies to:

 - Microsoft SNA Server, versions 2.11, 2.11 SP1, on platform(s):
    - the operating system: Microsoft Windows NT 
-------------------------------------------------------------------------------


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):

   Q137588 TN3270 Service Will Not Start with a Large Config File

Additional query words: prodsna

======================================================================
Keywords          : kbnetwork 
Technology        : kbAudDeveloper kbSNAServSearch
Version           : WINDOWS:2.11,2.11 SP1
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS
PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND.  MICROSOFT DISCLAIMS
ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  IN NO
EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR
ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT APPLY.

Copyright Microsoft Corporation 2001.