All 7 Amazon ElastiCache (Redis & Memcached) questions
More in Amazon ElastiCache (Redis & Memcached)
What is Amazon ElastiCache and why do applications use it? What is the main difference between the Redis and Memcached engines in ElastiCache? What caching strategies are commonly implemented using ElastiCache, such as lazy loading and write through? How does ElastiCache for Redis support cluster mode to scale beyond a single node's capacity? How can ElastiCache be secured within a VPC, and what encryption options are available? What monitoring metrics are most important to track for an ElastiCache deployment in production?
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AWS › Amazon ElastiCache (Redis & Memcached)

How does replication work in ElastiCache for Redis to provide high availability?

Intermediate

Answer

ElastiCache for Redis supports a primary replica architecture where a primary node handles all write operations and one or more replica nodes asynchronously receive copies of that data, and if Multi AZ is enabled, ElastiCache automatically detects a primary node failure and promotes a replica to become the new primary, minimizing downtime without requiring manual intervention.
aws elasticache create-replication-group --replication-group-id my-redis-group --replication-group-description 'Redis with replicas' --engine redis --num-cache-clusters 3 --automatic-failover-enabled
Real-world example A gaming platform enables Multi AZ automatic failover on its Redis replication group, so if the primary node fails unexpectedly during peak hours, a replica is automatically promoted and player sessions continue with minimal interruption.

Common follow-ups: How long does automatic failover typically take in ElastiCache for Redis?;Can replica nodes serve read traffic to reduce load on the primary?

AWS Backup & Disaster Recovery;Monitoring (CloudWatch)
All 7 Amazon ElastiCache (Redis & Memcached) questions