System design in numbers

Sizing exercises: how many servers, how much capacity, at what cost. Move the sliders, run the test against real-looking load, and see where the numbers break. Each exercise ends with the arithmetic worked out.

• Sale day capacity

  ★★★

  Pick how many app servers to run. Too few and the sale day melts them; too many and you blow the budget. Run the numbers, then run the test.

  Exercise 1