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Q174644: Perfmon Degrades SNA Server When Many 3270 LUs in Use

Article: Q174644
Product(s): Microsoft SNA Server
Version(s): winnt:2.11 (all SP),3.0 (all SP),4.0
Operating System(s): 
Keyword(s): kbnetwork
Last Modified: 12-JUN-2001

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The information in this article applies to:

- Microsoft SNA Server for Windows NT, versions 2.11 SP1, 2.11 SP2, 3.0 SP1, 3.0 SP2, 3.0 SP3, 3.0 SP4, 4.0 
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SYMPTOMS
========

When you use Windows NT Performance Monitor to monitor any SNA performance
objects every second, SNA Server performance degrades significantly when 150
users or more have an active 3270 session. Users with active 3270 sessions
receive host response delays from 20 seconds to two minutes.

CAUSE
=====

When you monitor SNA Server performance objects, SNA Server reports response
time monitor (RTM) performance data on every active 3270 LU. When a large number
of 3270 LUs are in use, this reporting can degrade 3270 performance for current
3270 users if a small Performance Monitor reporting interval is chosen (such as
the default one-second reporting interval in Windows NT Performance Monitor).

RESOLUTION
==========

To prevent the problem from occurring with SNA Server 2.11 or 3.0, follow these
steps:

1. Choose an infrequent Performance Monitor reporting interval, such as one
  minute or more, rather than the default of one second.

2. Do not continuously monitor SNA Server performance objects during production
  use

STATUS
======

Microsoft has confirmed this behavior with SNA Server versions 2.11, 3.0, and
4.0 and is investigating how to address this issue in future releases.

This problem was corrected in the latest SNA Server version 4.0 U.S. Service
Pack. For information on obtaining this Service Pack, query on the following
word in the Microsoft Knowledge Base (without the spaces):

  S E R V P A C K

The updated SNA Server 4.0 modules are:

  <snaroot>\system\snaservr.exe
  <snaroot>\system\trcservr.exe
  <snaroot>\system\snaperf.dll


MORE INFORMATION
================

For additional information about another possible performance problem, please
see the following article in the Microsoft Knowledge Base:

  Q168717 SNA Server Performance Degrades If Domain Controller Down

Additional query words:

======================================================================
Keywords          : kbnetwork 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ400NT kbSNAServ211NTSP1 kbSNAServ211NTSP2
Version           : winnt:2.11 (all SP),3.0 (all SP),4.0
Issue type        : kbbug
Solution Type     : kbfix

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