Redis proporciona alta disponibilidad a través de replicación (copias réplica de los datos), Redis Sentinel (monitoreo automático de failover) y Redis Cluster (sharding + replicación). Comprender esto es importante para ejecutar Redis de forma fiable en producción.
Replicación — primaria y réplicas
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
