# Underutilized ElastiCache node | Cloud Efficiency Hub Canonical: https://www.pointfive.co/efficiency-hub/inefficiencies/underutilized-elasticache-node ElastiCache clusters are often sized for peak performance or reliability assumptions that no longer reflect current workload needs. By: Yulia Perlis Updated: 2026-09-28 [Cloud Efficiency Hub](https://www.pointfive.co/efficiency-hub) # Underutilized ElastiCache Node The short version ElastiCache clusters are often sized for peak performance or reliability assumptions that no longer reflect current workload needs. Yulia Perlis AWS service [AWS ElastiCache](https://www.pointfive.co/efficiency-hub/cloud-services/aws-elasticache) Category [Databases](https://www.pointfive.co/efficiency-hub/service-category/databases) Reference CER-0152 Type Overprovisioned Resource ## Explanation Why the waste happens and who it affects. 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. ## Billing model The pricing dimensions that drive this cost. 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. ## How to detect 6 checks to find it in your estate. - 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 ## How to fix 4 ways to remove the waste. - 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 ## Documentation Vendor references for pricing and configuration. - [Amazon ElastiCache Pricing aws.amazon.com](https://aws.amazon.com/elasticache/pricing/) - [Monitoring use with CloudWatch Metrics docs.aws.amazon.com](https://docs.aws.amazon.com/AmazonElastiCache/latest/dg/CacheMetrics.html) ## Related inefficiencies [Browse the library](https://www.pointfive.co/efficiency-hub) - AWS ElastiCache CER-0321 ### [Suboptimal Cache TTL Strategy Causing Repeated Backend Execution](https://www.pointfive.co/efficiency-hub/inefficiencies/suboptimal-cache-ttl-strategy-causing-repeated-backend-execution) Organizations deploy ElastiCache to reduce load on backend systems - databases, APIs, and compute layers - by serving frequently accessed data from fast in-memory storage. However, when Time-to-Live (TTL) values are misaligned with actual... Databases - AWS ElastiCache CER-0284 ### [Outdated ElastiCache Engine Version Incurring Extended Support Charges](https://www.pointfive.co/efficiency-hub/inefficiencies/outdated-elasticache-engine-version-incurring-extended-support-charges) ElastiCache clusters continue running engine versions that have moved into extended support. While the service remains functional, AWS charges an ongoing premium for extended support that provides no added performance or capability. These... Databases - AWS ElastiCache CER-0146 ### [Non-Graviton ElastiCache Node on Eligible Workload](https://www.pointfive.co/efficiency-hub/inefficiencies/non-graviton-elasticache-node-on-eligible-workload) Many Redis and Memcached clusters still use legacy x86-based node types (e.g., cache.r5, cache.m5) even though Graviton-based alternatives are available. In-memory workloads tend to be highly compatible with Graviton due to their... Databases --- Source: the public page above. Product screenshots and illustrative interfaces are examples, not live customer data.