System design guides
The ideas behind the simulator, explained with the formulas you can use in a design review or an interview.
Caching in system design
A practical guide to caching for system design: cache-aside vs read-through, the hit-ratio formula, invalidation, TTLs, eviction and cache stampedes.
Load balancing and capacity planning
How to reason about server capacity with queueing theory: utilisation ρ = λ/cμ, Little’s law, load balancing algorithms, autoscaling and failover.
Message queues vs event streams
Queues vs streams in system design: how SQS, RabbitMQ and Kafka differ, the backlog formula, partitions vs consumers, retention and dead-letter queues.