Practice — Database Replication & Sharding (6 questions)

A leaderless key-value store keeps every key on N = 5 replicas. The operations team is choosing default write (W) and read (R) quorum sizes. They are considering W = 3, R = 3, W = 1, R = 5, and W = 2, R = 2.

1. For each configuration, state whether a read is guaranteed to observe the most recent acknowledged write, and explain the rule you used.
2. Walk through a concrete example with W = 2, R = 2: replicas A–E, a write acknowledged by two of them, and a read that misses it.
3. The system enables sloppy quorums with hinted handoff during outages. Which of your answers to part 1 changes, and why?