Capacity Model for Internet Transactions

Published: December 07, 2001

The purpose of capacity planning for Internet services is to enable Internet site deployments that:

  • Support transaction throughput targets.

  • Remain within acceptable response time boundaries.

  • Minimize the total cost of ownership of the host platform.

Conventional solutions to capacity planning often attempt to assign cost to Internet services by extrapolating generic benchmark measurements. To better meet the stated objectives of capacity planning, a methodology based on transaction cost analysis (TCA) has been developed at Microsoft for estimating system capacity requirements.

Client transactions are simulated on the host server by a load generation tool that supports standard network protocols. By varying the client load, transaction throughput is correlated with resource utilization over the linear operating regime. A profile is then defined based on anticipated user behavior. This usage profile determines the throughput target and other important transaction parameters from which resource utilization and capacity requirements are then calculated. This capacity model based on TCA has been successfully applied to estimate hardware platform deployment requirements for Microsoft Internet Information Server, Application Center, and Microsoft Exchange.


Included in this document:

  • Transaction Cost Analysis Methodology

  • Usage Profile

  • Site Profile

  • Instrumentation of Probes

  • Performance Measurement

  • Cost Equations

  • Model Verification

  • Capacity Planning Using Transaction Cost Analysis

  • Transaction Cost Analysis Requirements


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