# Suboptimal Use of On-Demand Instances in Fault-Tolerant EC2 Workloads

Canonical: https://www.pointfive.co/efficiency-hub/inefficiencies/suboptimal-use-of-on-demand-instances-in-fault-tolerant-ec2-workloads

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

# Suboptimal Use of On-Demand Instances in Fault-Tolerant EC2 Workloads

## Explanation

Many EC2 workloads-such as development environments, test jobs, stateless services, and data processing pipelines-can tolerate interruptions and do not require the reliability of On-Demand pricing. Using On-Demand instances in these scenarios drives up cost without adding value. Spot Instances offer significantly lower pricing and are well-suited to workloads that can handle restarts, retries, or fluctuations in capacity. Without evaluating workload tolerance and adjusting pricing models accordingly, organizations risk consistently overpaying for compute.

## Relevant Billing Model

EC2 is billed based on:

- Instance Type and Size - determines the base hourly rate

- Pricing Model

- On-Demand: Highest cost, flexible usage

- Spot: Deep discounts with interruption risk

- Reservations/Savings Plans: Lower cost for committed usage

On-Demand usage incurs the highest hourly rate. When applied to fault-tolerant workloads, it often leads to avoidable overspending.

## Detection

- Identify EC2 instances in non-production environments or batch frameworks running on On-Demand

- Review Auto Scaling Group and launch template settings for pricing model selection

- Cross-check usage patterns against workload type and fault tolerance characteristics

- Engage engineering teams to validate whether On-Demand usage is justified

## Remediation

- Reconfigure eligible workloads to use Spot Instances via launch templates or Auto Scaling policies

- Use mixed-instance and capacity-optimized allocation strategies for better availability

- Apply On-Demand only where availability, SLA, or licensing requirements demand it

- Encourage team-level cost reviews to identify low-risk transitions to Spot

## Relevant Documentation

- [AWS Spot Instances](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-spot-instances.html)

- [EC2 Pricing Models Overview](https://aws.amazon.com/ec2/pricing/)

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## At a glance

Reference

CER-0012

Cloud provider

AWS

Service

AWS EC2

Category

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

Inefficiency type

Suboptimal Pricing Model

## Contributed by

- ### Matt Weingarten

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Source: the public page above. Product screenshots and illustrative interfaces are examples, not live customer data.