Redis menyediakan ketersediaan tinggi (high availability) melalui replikasi (salinan replika data), Redis Sentinel (pemantauan failover automatik), dan Redis Cluster (sharding + replikasi). Memahami ini adalah penting untuk menjalankan Redis dengan boleh dipercayai dalam produksi.
Replikasi — primary dan replika
PRIMARY (master) → handles writes; asynchronously replicates data to replicas
REPLICAS (slaves) → copies of the primary's data; can serve READS (read scaling)
Write → Primary → async replication → Replicas (eventually consistent)
✓ Redundancy (replicas have copies) + read scaling (reads offloaded to replicas)
✗ Replication is ASYNC → a small lag; a failover could lose very recent writes
