Challenge 1: Scale a web app to 10,000 RPS
You inherit one web server and its relational database, which stays. Traffic has grown to 10,000 requests a second, 9 in 10 of them reads, and every page is personalized, so a CDN cannot cache it. Serve every request with p99 under 175 ms and no single point of failure, for at most 2,250 USD a month.
Traffic demand10,000 RPS90% reads, 10% writes
p99 latency target≤ 175 msSlowest 1% of requests
Availability≥ 99.9%Zero single points of failure
Monthly cloud budget≤ 2,250 USDA month, everything included