Q155417: XADM: LoadSim, Microsoft Exchange Server Load Simulation Tool

Article: Q155417
Product(s): Microsoft Exchange
Version(s): winnt:4.0
Operating System(s): 
Keyword(s): kbtool kbusage exc4
Last Modified: 21-JUL-1999

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The information in this article applies to:

- Microsoft Exchange Server, version 4.0 
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SUMMARY
=======

This article describes what the Microsoft Exchange Server Load Simulation Tool,
LoadSim.exe, was designed to do and what its software and hardware requirements
are. For more information, please see the documentation on the Microsoft
Exchange Server CD, Support\LoadSim\LoadSim.doc, the Microsoft Exchange
Performance: Concurrent Users Per Server white paper available on the Microsoft
TechNet CD.

For information on how to get the LoadSim version for Exchange Server 5.5, please
refer to the following Microsoft Knowledge Base article:

  Q196404 XADM: Load Simulator Missing in Exchange Server 5.5

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


As a performance tool, LoadSim is primarily used to help answer the question: How
many users per server does a Microsoft Exchange Server Support? This tool can be
used to generate a graph of perceived client response time as a function of the
number of active users.

LoadSim was designed to provide a realistic load on a Microsoft Exchange Server
computer by simulating the behavior of multiple Microsoft Exchange clients.
LoadSim takes advantage of the multithreading, multiprocessing, and shared
memory features in Windows NT to create and manage up to several hundred
simulated users on a single client computer. However, if you want to run a large
test (several hundred users or more), you need multiple LoadSim client
computers.

Tests
-----

You can use LoadSim to specify and run three kinds of tests:

- User Initialization, creates folders and messages in user mailboxes.

- Public Folder Initialization, sets up the Public Folder hierarchy.

- Load Simulation, simulates multiple users performing a wide variety of client
  actions including, reading mail, sending mail, Schedule+ actions, and use of
  Public Folders. This test can be set to simulate low, medium, and heavy
  client usage.

The first two tests are really just setup steps for the Load Simulation test.

You can specify many different test configuration options in LoadSim to simulate
the type of activity you expect to see in production and you can save each
configuration to a separate .SIM file. This allows you to run a particular
configuration multiple times and to use LoadSim in automated mode from the
command-line.

Software Requirements
---------------------

LoadSim should be run on Windows NT 3.51 or later. For demonstration purposes,
you can run LoadSim on Windows 95. However, if you are going to run large tests,
gather performance timing results, or perform directory import, you need to use
Windows NT. In addition, you must have a Microsoft Exchange client installed on
the computer running LoadSim.

Hardware Requirements
---------------------

If you use LoadSim for performance analysis, you need to make sure that your
client hardware doesn't adversely affect performance results. The response times
reported by LoadSim for user actions should be based primarily on server load,
not client hardware bottlenecks. To gather accurate performance timing data,
your client computer should have at least 32 MB of physical RAM. The number of
simulated clients that can be reasonably supported on one physical computer vary
with the nature of users chosen. If, for example, you use the Medium default
user setting, a 32 MB client computer should support 100 simulated users with
little or no degradation in client response time.

There are several limiting factors that affect the capability of a particular
computer to support a particular type and number of LoadSim users, the effects
of these factors vary depending on your topology, your hardware, and your user
definitions. Some important considerations are:

- Network bandwidth. One of the differences between 100 real users and 100
  LoadSim users is that you can run all 100 LoadSim users on one computer. You
  should make sure the network hardware on your client computers can handle the
  number of users per computer that you want to simulate.

- Memory and pagefile size. Each LoadSim process, and, to a lesser degree, each
  thread in each LoadSim process uses some amount of system memory on its
  client computer, both in physical RAM and virtual memory. You can use the
  Windows NT Performance Monitor to make sure that your LoadSim users aren't
  using too much system memory or causing excessive pagefile activity on your
  client computers.

- Disk I/O capacity. Some LoadSim user actions require disk access on the
  client computer. You should verify that your LoadSim users aren't exceeding
  the capacity of the I/O subsystem on each client computer.

Additional query words:

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Keywords          : kbtool kbusage exc4 
Technology        : kbExchangeSearch kbExchange400 kbZNotKeyword2
Version           : winnt:4.0
Issue type        : kbinfo

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