cloudpatterns.appClassroomKatasWhiteboardBlog
Station: Failure modes & availabilityStep 1 of 6Predict

Failure modes and availability

Lesson~9 minStep 1 of 6
  1. Predict (current)
  2. Name the parts
  3. Explain
  4. Explain 2
  5. Check
  6. Wrap up

Checkout, an online shop, takes orders. Every order passes four services: the checkout API, the cart, payments (which calls an outside payment provider) and the orders database. Each of them, on its own, is up 99.9% of the time — a respectable number.

So how often can a shopper actually place an order?

Every order at Checkout needs four services — the checkout API, the cart, payments and the orders database — and each one is up 99.9% of the time, failing independently. About what share of the time can a shopper place an order? Answer in percent, to one decimal.

This one is reading and questions — no simulation.