QuickReference

Memcached 

Features 

• Data distribution/partitioning

• Simple data structures

• Ephemeral persistence

• Multi-threaded

• TLS

use-case 

• For simple data

• Run large nodes with multiple cores or threads

• Ability to scale out and in

• Add or remove nodes as demands change

• Need to cache objects

Redis

Features 

Data distribution/partitioning

Complex data structures

Data loss and HA replication

Backup and restore

Semi-durable persistence

TLS

use-case 

• Supports complex data types

• Sort or rank in-memory datasets

• Persistence of key store

• Replicate data from primary to one or more read replicas for read intensive applications

• Need automatic failover if your primary node fails

• pub/sub capabilities to inform clients about events on server

• Backup/restore capabilities

• Need to support multiple databases

ElastiCache for Redis non-cluster mode

The following characteristics are for running ElastiCache for Redis non-cluster mode:

1. Only one primary instance support is available for up to five read replicas per primary node.

2. Automatic failover is supported. In the event that the primary node fails, one of the replicas is promoted to the primary role.

3. All write activity takes place in the primary node. Read activity may happen from any one of the nodes.

4. Multi-AZ configuration is supported.

5. As a cluster with a single shard, it is suitable when a small number of keys are used.

6. Non-cluster mode is used when a small number of large nodes make up the cluster.

ElastiCache for Redis cluster mode

The following characteristics describe running ElastiCache for Redis in cluster mode:

1. Supports up to five read replicas per primary node and supports multiple primary nodes (shards), up to a total of 500 nodes (with no replica)

2. Uses automatic node promotion 

3. Supports sharding as a means to distribute the load. Cluster mode is used when deploying a number of smaller nodes. It supports automatic node promotion in the event of primary node failure. The configuration endpoint is automatically updated.

ElastiCache for Memcached architecture

ElastiCache for Memcached is a Memcached-compatible, in-memory key-value store service that can be used as a cache or a data store. In addition to the performance of Memcached, it is also user friendly. ElastiCache for Memcached is fully managed, scalable, and secure, making it an ideal candidate for use cases where frequently accessed data must be in-memory. It is a popular choice for use cases such as web, mobile apps, gaming, ad tech, and ecommerce.

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