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CENTRAL UNIVERSITY
Lecture

CAP, PACELC and Consistency Models

A story about real trade-offs in distributed systems

/ CAP, PACELC and Consistency Models · Central University

Slide contents

  1. 1. CAP, PACELC and Consistency Models

    A story about real trade-offs in distributed systems

  2. 2. Lecture Map

  3. 3. CAP Theorem in One Phrase

  4. 4. C, A, and P: What's Inside

  5. 5. Consistency in CAP = Linearizability

  6. 6. Availability in the Theorem

  7. 7. How CAP Emerged

  8. 8. The 'Pick 2 of 3' Myth

  9. 9. Partitions: Rare, Not Exotic

  10. 10. Decisions Are Made Per Operation

  11. 11. C/A/P Are Spectrums

  12. 12. Partition Mode as State Machine

  13. 13. Latency Governs CAP

  14. 14. ACID vs CAP: Different C

  15. 15. BASE Answers Availability

  16. 16. Gilbert–Lynch Formal Definitions

  17. 17. Asynchronous Impossibility

  18. 18. Partial Synchrony Doesn't Help

  19. 19. CAP Takeaways for Architecture

  20. 20. CAP: What to Do in Failure

  21. 21. PACELC Formula

  22. 22. Why PACELC Was Needed

  23. 23. Latency vs Consistency in Normal Mode

  24. 24. PACELC Categories

  25. 25. PA/EL: Speed and Availability First

  26. 26. PC/EC: Consistency First

  27. 27. PA/EC: Reliable and Strict

  28. 28. PC/EL: Rare but Important Profile

  29. 29. Map PACELC to Product Needs

  30. 30. Calculate Latency/Consistency Budget

  31. 31. What PACELC Adds to CAP

  32. 32. Jepsen: Stress-Testing Distributed Systems

  33. 33. Why Architects Read Jepsen

  34. 34. Jepsen's Five-Step Cycle

  35. 35. Jepsen Failure Models

  36. 36. Typical Jepsen Findings

  37. 37. Jepsen Model Map: Two Branches, One Apex

  38. 38. Serializable vs Linearizable

  39. 39. Choose a Model for Product

  40. 40. Overall Framework: CAP + PACELC + Jepsen

  41. 41. Cassandra Through CAP/PACELC

  42. 42. Cassandra Tunable Consistency

  43. 43. How Cassandra Maintains Scale and Availability

  44. 44. References and Materials

    CAP: https://system-design.space/chapter/cap-theorem

    PACELC: https://system-design.space/chapter/pacelc-theorem

    Consistency Models (Jepsen): https://system-design.space/chapter/jepsen-consistency

    Cassandra: https://system-design.space/chapter/cassandra

    All 4 source chapters from system-design.space in one place.