Answer Key: Replication Strategies
Exercise 1: Choose Replication
Question: When do you use master-slave vs multi-master? What are the tradeoffs?
Answer
Master-Slave: - Strong consistency required - Read scaling needed - Can tolerate master failure downtime
Multi-Master: - High availability required - Write scaling needed - Can tolerate eventual consistency
Answer: Master-slave for consistency, multi-master for availability and write scaling.
Exercise 2: Handle Master Failure
Question: Your master-slave system loses its master. How does it recover?
Answer
Recovery Process: 1. Detect: Detect master failure 2. Promote: Promote slave to master 3. Update: Update routing to new master 4. Resume: Resume operations
Answer: Automatic failover, promote slave to master, update routing, resume operations.
Exercise 3: Design Quorum
Question: Design a quorum replication system. How many replicas? What's the quorum?
Answer
Quorum Design: - Replicas: 3 replicas (minimum for quorum) - Write quorum: 2 replicas (majority) - Read quorum: 2 replicas (majority) - Availability: Available if 2+ replicas available
Answer: 3 replicas, quorum of 2 (majority), available if majority available.