Why our platform needs Redis Sentinel

Transcript

1. Redis Sentinel High availability with your beloved Redis
2. Single server, single failure point Redis Instance Client Application
3. Multiple servers Redis Instance Client Application Redis Instance Redis Instance
4. Replication Redis Master Client Application Redis Slave Redis Slave
5. Replication Redis Master Client Application Redis Slave Redis Slave Async replication
6. Replication Use Case Redis Master Client Application Redis Slave Redis Slave Async replication Increase scalability, data safety Write to master, read from any
7. Still doesn’t improve failover Redis Master Client Application Redis Slave (Terminating) Redis Slave Read error
8. Still doesn’t improve failover Client Application Redis master (Terminating) Redis Slave Stale data Redis Slave Stale data
9. Failure event expectation Redis Master (terminating….) Client Application Redis Slave (being promoted..) Redis Slave
10. Failure event expectation New redis Master Client Application Redis Slave (just created) Redis Slave
11. Who decides the failure and recovery?
12. Redis Sentinel Redis Master Client Application Redis Slave Redis Slave Sentinel 2 Sentinel 3 Sentinel 1 Monitor Notify Clients
13. Judging Redis with Sentinel practically Consistency, Availability, Partition Tolerance? Consistency or Availability is depending on configuration, but Redis is not designed to be highly CP or AP.
14. High availability configuration Redis Master Client Application Redis Slave Redis Slave Sentinel 2 Sentinel 3 Sentinel 1
15. High availability configuration Redis Master Client Application Redis Slave Redis Slave Sentinel 2 Sentinel 3 Sentinel 1
16. High availability configuration Redis Master Client Application Redis Slave Redis Slave Sentinel 2 Sentinel 3 Sentinel 1 Network partition
17. High availability configuration Redis Master Client Application Redis Slave Redis Slave Sentinel 2 Sentinel 3 Sentinel 1 unavailable available available
18. High availability configuration Client Application Redis Slave Redis Master (terminating….) Sentinel 3 unavailable available available Sentinel 2 New redis Master Sentinel 1
19. However Client Application Redis Slave Redis Master (terminating….) Sentinel 3 unavailable available available Sentinel 2 New redis Master Sentinel 1 Lost w rite Async replication, remember?
20. High consistency configuration Client Application Redis Slave Redis Master (terminating….) Sentinel 3 unavailable available available Sentinel 2 New redis Master Sentinel 1 min-replicas-to-write 1 min-replicas-max-lag 10 stop!
21. Eventual Consistency Strict vs Eventual consistency
22. Multiple master to improve HA Client Application Redis Master Redis Slave Redis Slave Sentinel 2 Sentinel 3 Sentinel 1 Redis Master Redis Slave Redis Slave Sentinel 5 Sentinel 6 Sentinel 4 Redis Master Redis Slave Redis Slave Sentinel 8 Sentinel 9 Sentinel 7