Interactive clusters are intended for development and ad-hoc analysis, remaining active until manually terminated. When used to run scheduled jobs or production workflows, they often stay idle between executions—leading to unnecessary infrastructure and DBU costs. Job clusters are designed for ephemeral, single-job execution and automatically terminate upon completion, reducing runtime and isolating workloads. Using interactive clusters for production jobs leads to cost inefficiencies and weaker workload boundaries.
Workloads with consistently low CPU and memory usage may no longer serve active traffic or scheduled tasks, but continue reserving resources within the cluster. These idle deployments often remain after project migrations, feature deprecations, or experimentation. Removing inactive workloads allows node groups to scale down, reducing infrastructure costs without impacting active services.
Clusters that no longer run active workloads but remain provisioned continue incurring hourly control plane costs and may also maintain associated infrastructure like node groups or VPC components. Inactive clusters often persist after environment decommissioning, project shutdowns, or migrations. Decommissioning unused clusters eliminates unnecessary operational costs and simplifies infrastructure management.
When an EC2 instance is dedicated primarily to internet-facing traffic, regional differences in data transfer pricing can drive a substantial portion of total costs. Hosting such workloads in a region with higher egress rates leads to elevated expenses without improving performance. Migrating the workload to a lower-cost region can yield significant savings while maintaining equivalent service quality, especially when no strict latency or compliance requirements dictate the original location.
Running non-production clusters solely on On-Demand Instances results in unnecessarily high compute costs. Development, testing, and QA environments typically tolerate interruptions and do not require the continuous availability guaranteed by On-Demand capacity. Introducing Spot-backed node groups in non-production environments can significantly reduce infrastructure expenses without compromising business requirements.
Oversized instances within Auto Scaling Groups lead to inflated baseline costs, even when scaling adjusts the number of instances dynamically. When workloads consistently use only a fraction of the available CPU, memory, or network capacity, there is an opportunity to downsize to smaller, less expensive instance types without sacrificing performance. Right-sizing helps balance capacity and efficiency, reducing compute spend while preserving workload stability.
Detection:
This inefficiency occurs when an EC2 instance remains in a running state but is not actively utilized. These instances may be remnants of past projects, forgotten development environments, or temporarily created for testing and never decommissioned. If an instance shows consistently low or no CPU, network, or disk activity—and no active connections—it likely serves no operational purpose but continues to generate ongoing compute and storage charges.
This inefficiency arises when a virtual machine is left in a stopped (deallocated) state for an extended period but continues to incur costs through attached storage and associated resources. These idle VMs are often remnants of retired workloads, temporary environments, or paused projects that were never fully cleaned up. Without clear ownership or automated cleanup, they can persist unnoticed and accumulate avoidable charges.
When an EKS cluster remains on a Kubernetes version that has reached the end of standard support, AWS begins charging an additional Extended Support fee. These charges often arise from delays in upgrade cycles, uncertainty about workload compatibility, or overlooked legacy clusters. If the workload does not require the older version, continuing to run the cluster in this state results in unnecessary cost and technical risk.
When the EC2 instance types used for EKS node groups have a memory-to-CPU ratio that doesn’t match the workload profile, the result is poor bin-packing efficiency. For example, if memory-intensive containers are scheduled on compute-optimized nodes, memory may run out first while CPU remains unused. This forces new nodes to be provisioned earlier than necessary. Over time, this mismatch can lead to higher compute costs even if the cluster appears fully utilized.
