Problems / RAG and retrieval, medium

RAG answers stop during an outage

Retrieval works, but the answer model’s provider is down from 15 s to 30 s.

Free to open. Runs in your browser, no sign-up.

Your goals

Success ≥ 99% through the outage.

The traffic

25 requests a second for 30 seconds: 100% request (reads).

The system

What each component does in this design, and what calls it. The simulator mimics each one from these settings.

ComponentIts job hereSettings
Load balancerLoad balancerTraffic enters here.Calls AI app.Layer 4 balancers route by IP and port; layer 7 balancers read HTTP and can route by path or header.–
AI appApp serviceLoad balancer forwards to it.Calls Hybrid search, Model.Little's law: throughput ≈ concurrency ÷ latency. 200 slots at 50 ms serve about 4,000 req/s.3 replicas × 500 slots · timeout 30 s
Hybrid searchHybrid searchAI app calls it.Hybrid search combines keyword matching (BM25) with vector similarity.400 slots · 2 steps
ModelLLM endpointAI app calls it.Latency has two parts: time to the first token, then a steady stream of tokens per second.400 streams

Hints

Try it first. Open one hint at a time if you get stuck.

Hint 1

The vector search is fine.

Hint 2

The model is a single point of failure.

One way to solve it

Add a fallback answer model.

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