A Rework challenge from Foundations. Your shop has two kinds of busy. Every day traffic swings from a quarter of normal at night to twice normal in the afternoon, and on sale days a flash sale brings four times normal for a few seconds at a time. Keep 99 out of 100 requests under 300 ms through both, lose fewer than 1 in 100, and spend as little as you can.
The design you start with: p99 212ms, 0% of requests failing, 60/s answered.