# Underutilized Instances in EC2 Auto Scaling Group

Canonical: https://www.pointfive.co/efficiency-hub/inefficiencies/underutilized-instances-in-ec2-auto-scaling-group

[Cloud Efficiency Hub](https://www.pointfive.co/efficiency-hub) 

# Underutilized Instances in EC2 Auto Scaling Group

## Explanation

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:

- Identify Auto Scaling Groups where instances exhibit low average CPU, memory, or network utilization relative to their capacity.

- Review instance sizing in relation to historical workload peaks and scaling behavior.

- Assess whether smaller, more cost-effective instance types could support the same workload with acceptable performance.

- Evaluate launch configurations or templates to determine if default instance types were selected without performance optimization.

- Confirm with application and infrastructure owners that resizing aligns with performance, availability, and SLA requirements.

## Relevant Billing Model

EC2 instances are billed per second based on instance type, operating system, and purchase model (e.g., On-Demand, Reserved Instances, Spot Instances). Larger instance types incur higher charges regardless of whether the workload fully utilizes the available resources.

## Detection

- Identify Auto Scaling Groups where instances exhibit low average CPU, memory, or network utilization relative to their capacity.

- Review instance sizing in relation to historical workload peaks and scaling behavior.

- Assess whether smaller, more cost-effective instance types could support the same workload with acceptable performance.

- Evaluate launch configurations or templates to determine if default instance types were selected without performance optimization.

- Confirm with application and infrastructure owners that resizing aligns with performance, availability, and SLA requirements

## Remediation

- Evaluate smaller instance types that better match the workload's actual resource requirements.

- Update the launch template or configuration for the Auto Scaling Group to use the selected instance type, and deploy changes during a low-traffic window if needed.

- After downsizing, monitor performance metrics to ensure the workload continues to meet application and SLA expectations.

- Regularly reassess instance sizing as usage patterns evolve to maintain ongoing cost efficiency.

## Relevant Documentation

[Submit Feedback](https://hub.pointfive.co/inefficiencies/underutilized-instances-in-ec2-auto-scaling-group)

## At a glance

Reference

CER-0014

Cloud provider

AWS

Service

AWS EC2

Category

[Compute](https://www.pointfive.co/efficiency-hub/service-category/compute)

Inefficiency type

Underutilized Resource

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