SLO puzzle
Measure what users feel
A search service is technically up, but users report slow responses and stale results.
Puzzle target
Pick signals that show user-visible health rather than only machine health.
Not selected yet
Not selected yet
Not selected yet
Complete each design choice to unlock the review. The feedback above will point out what your current tradeoff misses.
Flash cards
Review the key moves
What is the main idea behind System Design: Observability and SLOs?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
Which statement best captures the main point of this lesson?
Put the learning moves in the order that makes the concept easiest to apply.
System design is a sequence of explicit tradeoffs. Start small: clarify the goal, estimate load, pick the simplest architecture, then name what breaks first.
| Design surface | What you decide |
|---|---|
| Requirements | Functional behavior, constraints, and non-goals |
| Scale | Reads, writes, storage, bandwidth, and latency target |
| Architecture | Clients, load balancer, services, cache, database, queue, and workers |
| Reliability | Failure mode, fallback, retry, and metric |
| Goal | Pick metrics and alerts that map to user-visible reliability, not just server health. |
Practice Task
- Define latency, error-rate, saturation, and business counters for the design.
- Use the design puzzle below to choose components and tradeoffs.
- Explain the bottleneck before adding more infrastructure.