Challenge 14: Capstone: a distributed cache
Build the cache tier itself. Your application servers call it directly with a client library, 50,000 times a second, 90% reads. A miss goes to the backing database, 10 ms away, which can take at most 7,000 reads a second, even while a cache node is down. p99 under 20 ms, at most 1,200 USD a month.
Traffic demand50,000 RPS90% reads, 10% writes
p99 latency target≤ 20 msSlowest 1% of requests
Availability≥ 99.99%N-1 failure survival (0 drops)
Monthly cloud budget≤ 1,200 USDA month, everything included