~/talk

Redundancy does not imply fault tolerance

Talkat Hydra 2020 · 2020-07-06..07-09· [distributed-systems, databases]
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slides:none on file

Measured eight popular distributed storage systems by injecting a single-block fault at a time (read corruptions, read/write errors) using a user-level FUSE injector ErrorFS, and finds that one faulty block on one node often causes silent user-visible corruption, data loss, unavailability, or spread of corruption rather than recovery from replicas. Root causes are undetected local faults, crash-or-truncate reactions, and unsafe local/global interactions. Built a protocol-aware recovery called control, applied to LogCabin and ZooKeeper, which remains safe and highly available with only 4–10% throughput overhead.

AI-written summary · about

  1. 0:00Intro
  2. 0:26Distributed Storage Systems
  3. 0:36Redundancy for Fault Tolerance
  4. 1:18Redundancy in Distributed Storage
  5. 1:54Storage Faults Are Prevalent
  6. 4:10Redundancy Does Not Imply Fault Toler
  7. 6:17Fundamental Problems: Summary
  8. 7:49Outline
  9. 9:29Fault Model: ext4 and btrfs
  10. 10:16Fault Injection Methodology
  11. 11:47Behavior Inference Methodology
  12. 12:28An Example: Redis
  13. 13:42Redis: Behavior Analysis
  14. 18:38Faults are often Undetected Locall
  15. 20:30Crashing - Common Local Reaction
  16. 21:54Crash and Corruption Handling are Enta
  17. 28:48How to Recover Faulty Data?
  18. 36:25RSM Overview
  19. 37:26Replicated State Update
  20. 38:46RSM Persistent Structures
  21. 40:01Current Approaches to Handling Fault
  22. 40:41Protocol-Oblivious: Crash
  23. 44:50Recovery Approaches Summary
  24. 46:14CTRL Overview
  25. 46:47CTRL Fault Model
  26. 47:26CTRL Guarantees
  27. 47:53CTRL Local Storage
  28. 48:51CTRL Distributed Recovery
  29. 49:12Properties of Consensus Protocols
  30. 50:37Follower Log Recovery
  31. 52:22Leader Log Recovery: Determining Commitment
  32. 53:14Leader Recovery: Determining Commi
  33. 56:15Evaluation
  34. 56:47Reliability Experiments Example
  35. 57:34Reliability Experiments Summary
  36. 58:28Reliability Results Summary
  37. 58:50Update Performance (SSD)
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