Processor Subsystem - Compaq 108164-003 - ProLiant - 800 White Paper

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HITE APER
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System memory - all the server's memory resource, but not including cache memory on
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processor boards or drive arrays. This is the amount of RAM installed in the system.
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The data shows that Exchange Server is primarily processor intensive. That is to say, the first
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resource to be consumed in an Exchange Server machine is the processor. With that in mind,
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most of the following data will be centered around an analysis of performance with varying CPU
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configurations.
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After the processor subsystem, it is a tossup between the disk subsystem and system memory as to
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which is more crucial. It's a bit of a balance, i.e. if the server has a high performance disk
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subsystem, then the system memory is more likely to reach capacity first. Conversely, if the
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system has lots of memory, then the disk subsystem is likely to reach capacity first.
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. . The cardinal rule to remember is this: if a subsystem is not a bottleneck, then adding more of that
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resource will not help the problem . In all likelihood, it will merely amplify the existing weakness
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in the system. For example, if an Exchange Server exhibits poor response time - and the processor
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subsystem is not a bottleneck - then adding more processors to the server will not improve
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response time.
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Following the processor subsystem section are some data pertaining to the disk subsystem and
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system memory. While there's enough variables in those to warrant a white paper of their own,
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these sections are included to provide a feel for how the Exchange Server system responds as
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different resources are adjusted.
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Processor Subsystem

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As mentioned above, the processor subsystem is usually the first to be exhausted in an Exchange
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Server system. Following are graphs showing how the different processor and server products
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from Compaq affect the performance of Microsoft Exchange Server.
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The value on the vertical axis is the LoadSim Score. The value on the horizontal axis is the
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number of LoadSim users.
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1P indicates one processor installed in the server, 2P indicates two processors, etc. Each section
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will describe the individual configuration of the Exchange Server computer being tested.
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In all these test, the Exchange Server computer is configured as shown, and Exchange Optimizer
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is run to set the Exchange system parameters. No manual tuning was done.
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