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Amazon Web Services (AWS) is a pioneer in the cloud computing industry, providing scalable and flexible computing resources to businesses and organizations worldwide. One of their innovative offerings is the EC2 Spot Instance service, which offers a cost-saving solution for businesses looking to optimize their cloud computing expenses.

In this article, we’ll explore the benefits and considerations of EC2 Spot Instances and how they can help businesses achieve cost optimization with their AWS workloads.

What are AWS EC2 Spot Instances?

EC2 Spot Instances are a cost-optimization solution offered by AWS that allows businesses to bid on unused EC2 capacity. Spot Instances are instances that are available at a lower cost than On-Demand Instances, but with the possibility of being interrupted by AWS. The price of Spot Instances changes based on supply and demand, and businesses can bid on the price they are willing to pay for the instance. If the spot price falls below the bid price, the instance will start running, and the business will pay the lower spot price.

Where can EC2 Spot Instances be used?

EC2 Spot Instances can be used for a variety of applications, including big data processing, high-performance computing, and scientific simulations. They can also be used for applications that are flexible with respect to availability, such as batch processing, load testing, and background processing.

  • EC2 Spot Instances are also suitable for applications that are stateless, meaning that the application does not store data locally, as they can be terminated at any time, and the data can be easily transferred to another instance.

EC2 Spot Instances, AWS, EC2, Spot Requests, Spot Interruptions, Spot Rebalancing, Cost Optimization

Difference between EC2 Spot Instances and EC2 On-Demand Instances

The following table summarizes the main differences between EC2 Spot Instances and EC2 On-Demand instances in terms of features, pricing, and availability.

EC2 Spot Instances EC2 On-Demand Instances
Cost-effective alternative to EC2 On-Demand instances Typically more expensive than EC2 Spot Instances
Users bid on unused EC2 computing capacity Users pay the full price for the EC2 computing capacity
Applications can be terminated at any time Applications are guaranteed to run until the user stops it or terminates the instance
Ideal for flexible, stateless applications Ideal for applications that require guaranteed computing capacity

Spot Instance Requests

Spot Instance Requests are a way for you to bid on unused EC2 instances and run them at a lower cost than On-Demand instances. You can use Spot Instance Requests for various use cases such as big data processing, batch jobs, and web services, among others. The key to using Spot Instances effectively is to understand when and why an instance may be interrupted.

  • Spot Instance Requests work like an auction, where you can place a bid on an EC2 instance and if the price is less than the current Spot price, you will get the instance.
  • The Spot price varies depending on the availability of the instances in a particular region.
  • If the price goes higher than your bid price, your instance will be terminated, but you will be given a two-minute warning to save any important data.

Spot Interruptions

Spot Instances are made available at a discounted rate, but there is a trade-off for that reduced cost. Spot Instances can be interrupted by AWS at any time if the instances are needed for On-Demand or Reserved Instances. This is because Spot Instances are made available from EC2’s unused capacity, and if that capacity is needed, AWS may terminate the Spot Instance.

The interruption of a Spot Instance is not always predictable, and it can happen at any time without warning. This can cause some challenges for users who rely on these instances for critical workloads, as the interruption can cause data loss or application downtime.

However, AWS provides several tools and resources to help users manage Spot Instances interruptions.

  • You can use the EC2 Instance Rebalancing feature to automatically replace interrupted instances with new ones.
  • You can also use Amazon CloudWatch Alarms to monitor the health of your instances and take action if necessary.
  • Additionally, you can use Amazon Elastic Block Store (EBS) to store your data and attach it to a new instance if your current instance is interrupted.

Spot Instance Rebalance Recommendations and Strategy

EC2 Spot Instances can be unpredictable and may be terminated by AWS at any time. To help ensure the availability of EC2 Spot Instances and minimize the impact of interruptions, it is important to implement a rebalance strategy.

  • Rebalancing is the process of replacing terminated Spot Instances with new instances, and helps ensure that the application continues to run smoothly even in the face of interruptions.

EC2 Auto Scaling

AWS provides several tools and resources to help users implement a rebalance strategy. For example, users can use EC2 Auto Scaling to automatically replace terminated Spot Instances with new instances. EC2 Auto Scaling allows users to define a minimum number of instances to run, and automatically replaces any terminated instances.

EC2 Instance Rebalancing

EC2 Instance Rebalancing is a feature that automatically replaces terminated Spot Instances with new instances. EC2 Instance Rebalancing helps ensure that the desired number of instances is maintained, and can help minimize the impact of interruptions.

EC2 Spot Instance Advisor

EC2 Spot Instance Advisor provides recommendations on the best Spot Instance types to use, as well as the best utilization rates and rebalancing strategies. The EC2 Spot Instance Advisor takes into account the user’s workload and budget, and provides recommendations to help ensure cost optimization and reduce the side effects of interruptions.

  • It is important to note that EC2 Auto Scaling and EC2 Instance Rebalancing are only available for Amazon Linux and Windows Server instances. For other operating systems, users can implement their own rebalancing strategy, such as using a custom script or a third-party tool.

Spot Instance Fleets

Spot Instance Fleet is a feature within EC2 that allows users to manage multiple Spot Instance Requests as a single fleet. This is especially useful for users with large-scale, flexible workloads that require multiple instances to run simultaneously. With Spot Instance Fleet, users can easily manage the desired number of instances and their utilization, as well as monitor their health and replace any instances that are interrupted. They can also view their metrics on AWS CloudWatch.

Spot Instance Limits

AWS EC2 Spot Instances have limits in place to ensure the fair usage of EC2 resources. The limits can vary depending on the type of instances and the availability of EC2 capacity. Users can view their current Spot Instance limits by accessing the EC2 Dashboard in the AWS Management Console.

  • If the user requires more Spot Instance capacity, they can request an increase by submitting a limit increase request to AWS Support.
  • For example, let’s consider a user who wants to launch 100 Spot Instances for a big data processing application. If the user is already running 50 Spot Instances, they may not be able to launch the additional 50 instances due to their current Spot Instance limit. In this case, the user would need to submit a limit increase request.

Cost Optimization Advantages of EC2 Spot Instances

When it comes to cost optimization, EC2 Spot Instances have several benefits over On-Demand Instances and Reserved Instances. A few are listed below:
  1. Cost Savings:  EC2 Spot Instances are available at a much lower cost than On-Demand Instances, making them a great option for cost-conscious organizations. EC2 Spot Instances allow organizations to save up to 90% on their Amazon EC2 computing costs, compared to On-Demand Instances. This cost savings can be substantial and can greatly impact an organization’s bottom line.
  2. Scalability: Organizations can purchase EC2 Spot Instances in any quantity, and start and stop them as needed. This scalability makes it easy for organizations to handle spikes in demand without having to pay for additional computing resources they may not need. This is especially helpful when using compute services like AWS EMR
  3. Flexibility: EC2 Spot Instances offer flexibility, allowing organizations to configure their computing resources to meet their specific needs. For example, organizations can choose the operating system, software, and hardware they need, without being locked into a particular configuration. This flexibility allows organizations to quickly and easily configure their computing resources to meet their specific needs, without having to make significant investments in hardware or software.


In conclusion, AWS EC2 Spot Instances provide a cost-effective way to utilize Amazon Web Services’ computing resources. With savings up to 90% compared to On-Demand Instances, EC2 Spot Instances are a great option for organizations looking to optimize their computing costs. With features like Recommendations, Advisor and Fleets, EC2 Spot Instances offer scalability, flexibility, and cost savings all in one package.

So, if you’re looking to save some pennies on your cloud computing costs, consider taking advantage of AWS EC2 Spot Instances. After all, why pay full price for a cloud, when you can have it on a spot!

Adarsh Rai

Adarsh Rai, author and growth specialist at Economize. He holds a FinOps Certified Practitioner License (FOCP), and has a passion for explaining complex topics to a rapt audience.

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