Determining your requirements - Amazon ElastiCache
Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Determining your requirements


Knowing the answers to the following questions helps make creating your cluster go smoother:

Do you want to use ElastiCache serverless or instance based service?

If you want to use serverless cache, simply ensure that you have properly configured your VPC, subnets, and security groups properly. For more details, see Access Patterns for Accessing an ElastiCache Cache in an Amazon VPC. If you want to use instance based ElastiCache, continue reading.

  • Which node instance type do you need?

    For guidance on choosing an instance node type, see Choosing your Memcached node size.

  • Will you launch your cluster in a virtual private cloud (VPC) based on Amazon VPC?


    If you're going to launch your cluster in a VPC, make sure to create a subnet group in the same VPC before you start creating a cluster. For more information, see Subnets and subnet groups.

    ElastiCache is designed to be accessed from within Amazon using Amazon EC2. However, if you launch in a VPC based on Amazon VPC and your cluster is in an VPC, you can provide access from outside Amazon. For more information, see Access Patterns for Accessing an ElastiCache Cache in an Amazon VPC.

  • Do you need to customize any parameter values?

    If you do, create a custom parameter group. For more information, see Creating a parameter group.

  • Do you need to create your own VPC security group?

    For more information, see Security in Your VPC.

  • How do you intend to implement fault tolerance?

    For more information, see Mitigating Failures.

Memory and processor requirements

The basic building block of Amazon ElastiCache is the node. Nodes are configured singularly or in groupings to form clusters. When determining the node type to use for your cluster, take the cluster’s node configuration and the amount of data you have to store into consideration.

The Memcached engine is multi-threaded, so a node’s number of cores impacts the compute power available to the cluster.

Memcached cluster configuration

ElastiCache for Memcached clusters are comprised of from 1 to 60 nodes. The data in a Memcached cluster is partitioned across the nodes in the cluster. Your application connects with a Memcached cluster using a network address called an Endpoint. Each node in a Memcached cluster has its own endpoint which your application uses to read from or write to the specific node. In addition to the node endpoints, the Memcached cluster itself has an endpoint called the configuration endpoint. Your application can use this endpoint to read from or write to the cluster, leaving the determination of which node to read from or write to up to Automatically identify nodes in your cluster.

For more information, see Managing clusters.

Scaling requirements

All clusters can be scaled up by creating a new cluster with the new, larger node type. When you scale up a Memcached cluster. the new cluster starts out empty.

Amazon ElastiCache for Memcached clusters can be scaled out or in. To scale a Memcached cluster out or in you merely add or remove nodes from the cluster. If you have enabled Automatic Discovery and your application is connecting to the cluster’s configuration endpoint, you do not need to make any changes in your application when you add or remove nodes.

For more information, see Scaling ElastiCache for Memcached in this guide.

Access requirements

By design, Amazon ElastiCache clusters are accessed from Amazon EC2 instances. Network access to an ElastiCache cluster is limited to the account that created the cluster. Therefore, before you can access a cluster from an Amazon EC2 instance, you must authorize the Amazon EC2 instance to access the cluster. The steps to do this vary, depending upon whether you launched into EC2-VPC or EC2-Classic.

If you launched your cluster into EC2-VPC you need to grant network ingress to the cluster. If you launched your cluster into EC2-Classic you need to grant the Amazon Elastic Compute Cloud security group associated with the instance access to your ElastiCache security group. For detailed instructions, see Accessing your cluster in this guide.

Region, Availability Zone and Local Zone requirements

Amazon ElastiCache supports all Amazon regions. By locating your ElastiCache clusters in an Amazon Region close to your application you can reduce latency. If your cluster has multiple nodes, locating your nodes in different Availability Zones or in Local Zones can reduce the impact of failures on your cluster.

For more information, see the following: