Replication mantiene copias de datos en múltiples servidores — para disponibilidad (sobrevivir fallos), escalado de lecturas (servir lecturas desde copias), y distribución geográfica. Diferentes estrategias (primaria-réplica, multiprimaria, síncrona vs asíncrona) implican concesiones.
Por qué es importante
✓ AVAILABILITY/redundancy → if one copy fails, others have the data (no data loss, failover)
✓ READ SCALING → serve reads from replicas (offload the primary) → handle more reads
✓ GEO-DISTRIBUTION → copies near users (lower latency); disaster recovery
→ replication is fundamental to reliable, scalable data systems.
