Underutilized ElastiCache Node

When memory and CPU usage remain consistently low, the node is likely overprovisioned. For Redis, memory is typically the primary sizing constraint, while Memcached workloads may be more CPU-sensitive. In dev, staging, or lightly used production environments, some nodes may be entirely idle.It's important to evaluate usage patterns in context - for example, replica nodes in Redis Multi-AZ configurations may show low utilization by design, but still serve a high-availability purpose. However, in non-critical environments or where HA is not required, those nodes can often be downsized or removed. Additionally, older ElastiCache instance types (e.g., r4, m3) are frequently less cost-efficient than newer generations like r6g or r7g, offering further savings through modernization.

ElastiCache nodes are billed per instance-hour, based on:

• Instance type and size (e.g., cache.r6g.large)
• Engine type (Valkey, Redis OSS or Memcached; Valkey node-based pricing is 20% lower than Redis OSS)

Charges apply continuously while provisioned, regardless of usage or traffic.

• Review utilization metrics for each ElastiCache node:
• Memory usage for Redis
• CPU usage for Memcached and write-heavy Redis
• Identify nodes with consistently low utilization (e.g., <30%) over a representative period
• Exclude replica nodes in HA configurations unless running in non-critical environments
• Correlate utilization with environment type and business function

• Rightsize nodes to smaller instance types that align with observed usage
• Modernize to newer instance families, or move Redis OSS clusters to Valkey, when possible to improve price-performance
• Remove idle or redundant nodes in dev, staging, or non-HA environments
• Incorporate cache sizing reviews into routine infrastructure audits

• Amazon ElastiCache Pricingaws.amazon.com
• Monitoring use with CloudWatch Metricsdocs.aws.amazon.com