ElastiCache
- ElastiCache is a web service
- Used to set up, manage, and scale distributed in-memory cache environments in AWS.
- Provides a high performance, resizable, and cost-effective in-memory cache
- Removes complexity associated with deploying and managing a distributed cache environment.
- Works with the Redis and Memcached engines
- By default, the AWS SDKs, AWS CLI, ElastiCache API, and ElastiCache console reference the US-West (Oregon) region.
- is a web service
- makes it easy to
- deploy
- operate
- scale an in-memory data store or cache in the cloud.
- Can be used for DB caching in conjunction with services like RDS
- Web service that makes it easy to deploy, operate, and scale in memory cache in the cloud
- Improves the performance of web applications by allowing you to retrieve information from fast, managed in-memory caches, instead of relying entirely on slower disk based databases
- Improves application performance by storing critical pieces of data in memory for low-latency access
- Cached information may include the results of I/O intensive database queries or the results of computationally intensive calculations
- Supports 2 open-source in-memory caching engines:
- Memcached:
- Widely adopted memory object caching system
- Elasticache is protocol complaint with memcached, so popular tools that you use today with existing memcached environments will work seamlessly with the service
- No Multi AZ support
- Redis:
- Popular open-source in-memory key-value store that supports data structures such as sorted sets and lists
- Elasticache supports Master/Slave replication and Multi-AZ which can be used to achieve cross AZ redundancy
- Good choice if db is read heavy and not prone to frequent changing
- Memcached:
| All Region Resource or Operation | DefaultLimit | Description |
| Nodes per region: | 50 | The maximum number of nodes across all clusters in a region. |
| Nodes per cluster (Memcached): | 20 | The maximum number of nodes in an individual Memcached cluster. |
| Nodes per cluster (Redis): | 1 | The maximum number of nodes in an individual Redis cluster. |
| Clusters per replication group (Redis): | 6 | The maximum number of clusters in a Redis replication group. One is the read/write primary. All others are read only replicas. |
| Parameter groups per region: | 20 | The maximum number of parameters groups you can create in a region. |
| Security groups per region: | 50 | The maximum number of security groups you can create in a region. |
| Subnet groups per region: | 50 | The maximum number of subnet groups you can create in a region. |
| Subnets per subnet group: | 20 | The maximum number of subnets you can define for a subnet group. |
ElastiCache Node
- Node is the smallest building block in Elasticache
- Node can exist in isolation from
- Node can be in some relationship to other nodes.
- It is a fixed-size chunk of secure, network-attached RAM.
- Each node runs an instance of the engine and version that was chosen during cluster creation.
- Scale the nodes in a cluster up or down to a different instance type.
ElastiCache operations for clusters:
- Creating a cluster
- Modifying a cluster
- Taking snapshots of a cluster (all versions of Redis)
- Deleting a cluster
- Viewing the elements in a cluster
- Adding or removing cost allocation tags to and from a cluster