  The performance of successful Web-based e-commerce services has all the
allure of a roller-coaster ride: accelerated fiscal growth combined with the
ever-present danger of running out of server capacity. This chapter presents a
case study based on the author's own capacity planning engagement with one of
the hottest e-commerce Web sites in the world. Several spreadsheet techniques
are presented for forecasting both short-term and long-term trends in the
consumption of server capacity. Two new performance metrics are introduced for
site planning and procurement: the effective demand, and the doubling period.
