You inherited this system from an engineer who never met a component they didn't like. The load is modest and read-heavy — nowhere near what this stack was built for — and the burn rate is eating the runway. Nothing here is broken; there's just too much of it. Strip it back to the smallest design that still meets the bar.
Requirements
Functional
·A standard read-mostly app — nothing new to build, just right-size what's already running
Non-functional
·~150 requests/sec
·95% reads
·p99 latency ≤ 150ms
·99% availability
Constraints
·Budget: $6/hr or less — the inherited stack costs $12/hr for load it doesn't need
Out of scope
·New features — this is a cost pass on an existing system, not a redesign
TrafficRequests per second — the rate of incoming traffic this level throws at your system.
~150 r/s · read-heavy
95% reads · 5% writesWhat fraction of requests are reads (fetches) vs writes (updates) — this decides which components sit on the hot path.
Win conditions
p99 latency99% of requests finish at or under this time — a stricter tail-latency bar than p95 that catches worst-case slowness.≤ 150ms
availabilityThe share of legitimate requests that succeeded, out of everything sent your way. 99% still means 1 in 100 users saw an error.≥ 99%
throughputHow many requests per second your system actually completed — not requested, completed.≥ 140 r/s
error rateThe share of requests that failed outright: timeouts, drops, or capacity overload.≤ 2%
costWhat your architecture costs to run per hour, based on the instances and components you've wired up.≤ $6/hr
Press enter or space to select a node. You can then use the arrow keys to move the node around. Press delete to remove it and escape to cancel.
Press enter or space to select an edge. You can then press delete to remove it or escape to cancel.
Drag components from the right → connect their handles → Run.
Drag onto canvas
Components
Client
ClientWhere traffic originates.
Compute
API GatewayFront door — the app tier requests pass through.
500 r/s · 20ms · $2/hr
Backend
350 r/s · 25ms · $2/hr
Lvl 7
Storage
SQL DatabaseRelational store. Durable, but the lowest throughput.
200 r/s · 50ms · $3/hr
NoSQL DB3× the throughput of SQL — at a premium. Pay for it only when the load demands it.
600 r/s · 30ms · $4/hr
Redis CacheIn-memory read-cache — absorbs repeated reads. Useless for writes.