Let’s get a quick overview of Amazon ElastiCache for Redis and Memcached from an AWS certification perspective. We will look at important certification questions regarding Amazon ElastiCache for Redis and Memcached.
You will learn
- What is Amazon ElastiCache?
- What are the options that Amazon ElastiCache offers?
- When do we use Amazon ElastiCache for Redis vs Amazon ElastiCache for Memcached?
- How is Amazon ElastiCache for Redis different from Amazon ElastiCache for Memcached?
Amazon ElastiCache
Amazon ElastiCache allows you to seamlessly set up, run, and scale popular open-Source compatible in-memory data stores in the cloud. Build data-intensive apps or boost the performance of your existing databases by retrieving data from high throughput and low latency in-memory data stores. Amazon ElastiCache is a popular choice for real-time use cases like Caching, Session Stores, Gaming, Geospatial Services, Real-Time Analytics, and Queuing.
- Managed service providing highly scalable and low latency in-memory data store
- Used for distributed caching
- Two Options:
- Redis
- Memcached
Amazon ElastiCache for Redis
- Highly scalable and low latency in-memory data store
- Can be used as a cache, database or message broker
- Automatic failover with Multi-AZ deployments (if enabled)
- Supports backup and restore
- Supports encryption at-rest (KMS) and in-transit
- Use cases:
- Caching
- Session Store
- Chat and Messaging
- Gaming Leader boards
- Geospatial Apps (Ride hailing, restaurant recommendations)
- Queues
Amazon ElastiCache for Redis - Cluster
- Shard - collection of one or more nodes
- One node acts as read/write primary
- Other nodes act as read replicas (up to five read replicas)
- In case of failure:
- Primary node is replaced
- If Multi-AZ replication group is enabled, read replica is promoted to primary
- DNS entry is updated
ElastiCache Redis - Backup and Snapshot
- Uses native backup feature of Redis (stored to S3)
- Recommended to perform snapshot against read replicas
- You can schedule snapshots
- Configure backup window and
- Days of backup you want to store
- Manual snapshots are available until they are manually deleted
Amazon ElastiCache for Memcached
- Simple caching layer intended for use in speeding up dynamic web applications
- Pure cache
- Non-persistent
- Simple key-value storage
- Ideal front-end for data stores like RDS or DynamoDB
- Can be used as a transient session store
- Create upto 20 cache nodes
- Use Auto Discovery to discover cache nodes
Amazon ElastiCache for Memcached - Limitations
- Backup and restore NOT supported
- Does not support encryption or replication
- Does not support snapshots
- When a node fails, all data in the node is lost
- Reduce impact of failure by using large number of small nodes
ElastiCache Memcached vs Redis
- Use ElastiCache Memcached for
- Low maintenance simple caching solution
- Easy horizontal scaling with auto discovery
- Use ElastiCache Redis for
- Persistence
- Publish subscribe messaging
- Read replicas and failover
- Encryption