Course contents
On this page
Lesson plan 36: Separated compute and storage
Compare shared-nothing, shared-storage, and separated compute/storage architectures.
Placement: Part 6: Scaling execution and state delivery.
Prerequisites: Lesson 35: Capacity and multitenancy, plus the earlier dependency chain.
Learning outcomes
- Compare shared-nothing, shared-storage, and separated compute/storage architectures.
- Explain remote-read latency, object-storage granularity, durability ownership, and cache warming.
- Evaluate elasticity using startup, placement, cache state, and recovery costs as well as steady-state throughput.
- Separate a general mechanism, a documented implementation choice, and an illustrative numerical assumption.
Teaching sequence
- Establish the motivating situation: A newly scaled compute node increases remote reads because its cache is empty.
- Introduce the vocabulary and the correctness obligation before an optimization. Define shared nothing, shared storage, remote storage.
- Develop the mechanism: Trace data, log, metadata, and cache ownership separately; include remote-failure and recovery paths.
- Follow the complete worked example: A 2 TB working set warmed at an effective 1 GB/s requires 2000 s absent reuse or prefetch overlap. Explain the assumptions, intermediate units, and limiting interpretation.
- Extend the scenario to changed load, skew, or failure, explaining object storage, tiering, elasticity, cold caches.
- Connect the mechanism to a documented implementation and an alternative with a different workload fit. Close by stating the remaining cost and the next lesson dependency.
Required chapter material
Use a complete execution trace or worked calculation, supported by an annotated static diagram or table. Include language-neutral pseudocode or labeled SQL when it clarifies the mechanism. State preconditions, ownership, visibility, and failure boundaries for algorithms. Describe operational costs as well as the normal path. All questions raised in the narrative must be resolved in the text.
Visual explanation
A compute/cache/storage diagram labels local and remote paths; a cold-start timeline quantifies the minimum data-loading work after compute replacement. The accompanying prose explains the arrows, state changes, or table entries so the lesson remains understandable in a plain Markdown reader.
Editorial checks
Confirm that the numerical example agrees with its units and assumptions. Check that a faster path preserves the stated contract, or explicitly identify the changed guarantee. Keep hypothetical figures separate from product measurements. Explain both an appropriate use and a limitation of the case design. Check terminology against the glossary and links against the course index.