Ensure that all your AWS ElastiCache Reserved Nodes (RN) have corresponding cache nodes running within the same account or within any AWS accounts members of an AWS Organization (if there is any). A corresponding cache node is a running ElastiCache cluster node that matches the reservation parameters such as Region and Node Type.
When an Amazon ElastiCache RCN is not in use (i.e. does not have an active corresponding cache node) the investment made is not properly exploited. For example, if you reserve a cache.m3.large ElastiCache cluster node within US East (N.Virginia) region but you don't create a cache node with the same type in the same region of the same AWS account or in any other linked AWS accounts within your AWS Organization, the specified ElastiCache RCN is considered unused and your investment has a negative return. Note: To receive the right cost optimisation recommendations, you need to enable the Cost Optimisation package for your account and plug in all your AWS Billing accounts into Cloud Conformity using the console.
To determine if you have any unused ElastiCache RCNs within your AWS account or your AWS Organization (if any), perform the following:
Because AWS ElastiCache Reserved Cache Nodes are reserved for you at purchase, you cannot modify, cancel or sell these reservations and you will be billed for these resources regardless of whether you use them. To make use of your investment, you can provision and utilize a corresponding cache node for each unused RCN purchased within the current AWS account or within any other member accounts available in your AWS Organization (if you are using one). To create ElastiCache cache nodes that match the RCNs purchase criteria, perform the following:Note: As example, this section will explain how to create a new ElastiCache Redis cache cluster within the same AWS region.