Amazon EC2, a popular cloud computing service, offers users the option to choose between on-demand instances and spot instances.

On-demand instances provide immediate access to computing resources without the need for bidding. They are known for their stability and consistent performance, making them suitable for applications that require continuous availability.

In contrast, spot instances are obtained through an auction or bidding system for unused capacity. To launch a spot instance, users specify a maximum bid price, and if the bid price is below the current market price, the instance is launched.

Spot instances can be more cost-effective than on-demand instances and are often used for fault-tolerant and flexible applications. However, there is a risk of losing access to spot instances if demand exceeds available capacity.

This article aims to explore the differences between on-demand and spot instances, focusing on factors other than pricing that make spot instances a unique option for users of Amazon EC2.

Types of Instances

On-demand instances, reserved instances, and spot instances are the three types of instances available in Amazon EC2, each with distinct characteristics and suitability for different applications.

On-demand instances are the default mode and require no long-term commitment. They provide immediate access without the need for bidding and are not affected by demand fluctuations, offering stability and consistent performance.

Reserved instances guarantee a selected instance type in a chosen region or availability zone and come with capacity guarantees. They are not affected by spot instance terminations and are a cost-effective option for critical applications.

Spot instances, on the other hand, utilize spare compute capacity through an auction/bidding system. They can be terminated if free capacity is exhausted or if the bid price is exceeded, but they can be more cost-effective than on-demand instances. They are suitable for fault-tolerant and flexible applications and offer flexibility in managing costs. However, they carry the risk of losing access if demand increases.

On-demand Instances

Immediate access without bidding is one of the key characteristics of on-demand instances. These instances are the default mode in Amazon EC2 and do not require a long-term commitment. On-demand instances provide stability and consistent performance as they are not affected by demand fluctuations. They are suitable for applications that require continuous availability.

With on-demand instances, users have the flexibility to start and stop instances as needed, paying only for the hours they use. This pay-as-you-go pricing model allows users to scale their resources up or down based on their requirements.

On-demand instances are a convenient option for users who need immediate access to compute resources without the need to bid or wait for spot instances to become available.

Reserved Instances

Reserved instances are a cost-effective option for critical applications as they guarantee the selected instance type in the chosen region or availability zone and provide capacity guarantees.

Unlike spot instances, reserved instances are not affected by spot instance terminations. This ensures that the reserved instances will always be available, providing stability and consistency in performance.

The long-term commitment of reserved instances allows organizations to plan and budget effectively for their infrastructure needs.

Additionally, reserved instances offer a cost advantage over on-demand instances, making them an attractive choice for applications with predictable and steady workloads.

By utilizing reserved instances, organizations can optimize their costs while ensuring the availability and reliability of their critical applications.