An application development team complains that they are experiencing performance issues with ElastiCache. After investigation, a database specialist determines that the ElastiCache cluster does not have sufficient memory allocated for non-data use. How can the specialist solve this issue?

Answer options:

A.Using AWS elasticache modify-cache-cluster CLI command, set reserved-memory parameter to 50.
B.Using AWS elasticache modify-cache-cluster CLI command, set the reserved-memory-percent parameter to 50.
C.Create a custom parameter group with reserved-memory parameters set to 50. Apply the custom parameter group to the cluster.
D.Create custom parameter group with the reserved-memory-percent parameter to 50. Apply the custom parameter group to the cluster.

Answer: D
Options A and B are incorrect because the configuration parameters of an ElastiCache cluster must be modified using custom parameter groups.
Option C is incorrect because it is recommended to use the reserved-memory-percent parameter. Each node in a cluster can be of a different type. This means that each node can have a different maximum memory. Therefore, using the reserved-memory parameter would require a different value for this parameter for each node depending on the node’s type and maximum memory. In turn, this requires the creation of a separate custom parameter group for each node type. To simplify the operation of clusters with various node types, you can use the reserved-memory-percent parameter. In this way, one parameter can be configured, and one parameter group can be used to manage the cluster’s reserved memory, regardless of the node types comprising the cluster. Therefore, option D is CORRECT.
Reference:
https://docs.aws.amazon.com/AmazonElastiCache/latest/red-ug/redis-memory-management.html