Raymond Lewallen

I had this oddly named file in My Documents, and opened it up to see what it was.  Turned out to be a whitepaper I had downloaded years ago on Transaction Cost Analysis – Capacity Model for Internet Transactions.  It was written by a couple of folks over at Microsoft who develop TCA methodologies for Microsoft for depolying servers such as Site Server, Exchange and Commercial Internet System.  The paper includes how to do an appropriate TCA as well as providing formulas for doing the calculations.  Download here.

The purpose of capacity planning for Internet services is to minimize the total dollar cost of ownership of the hosting platform in such a way which supports transaction throughput targets and ensures response times remain within acceptable bounds. Conventional solutions often attempt to cost Internet services through extrapolation of generic benchmark measurements. To satisfy this optimization objective more effectively, a methodology based on transaction cost analysis (TCA) is developed for estimating system capacity requirements.

Client transactions are simulated on the host server by a load generation tool which supports standard network protocols. By varying the client load a correspondence is made which relates transaction rate with resource utilization over the linear operating regime. A usage profile is defined which is intended to capture anticipated user behavior. This profile determines the throughput target and other important transaction parameters from which resource utilization and capacity requirements are then calculated.