Amazon EC2 Spot FAQs

Q. What is a Spot Instance?

Spot instances are spare EC2 capacity that can save you up 90% off of On-Demand prices that Amazon Web Services can interrupt with a 2-minute notification. Spot uses the same underlying EC2 instances as On-Demand and Reserved Instances, and is best suited for fault-tolerant, flexible workloads. Spot instances provides an additional option for obtaining compute capacity and can be used along with On-Demand and Reserved Instances

Q. How is a Spot instance different than an On-Demand instance or Reserved Instance?

While running, Spot instances are exactly the same as On-Demand or Reserved instances. The main differences are that Spot instances typically offer a significant discount off the On-Demand prices, your instances can be interrupted by Amazon EC2 for capacity requirements with a 2-minute notification, and Spot prices adjust gradually based on long term supply and demand for spare EC2 capacity. See here for details.

Q. How do I purchase and start up a Spot instance?

Spot instances can be launched using the same tools you use launch instances today, including Amazon Web Services Management Console, Auto-Scaling Groups, Run Instances and Spot Fleet. In addition many Amazon Web Services services support launching Spot instances such as EMR, Cloudformation.

Spot instances are easy to launch. Add a single parameter to the same API used to launch OD instances - instances will be launched immediately as long as capacity is available.

See here for more details on how to request Spot instances.

Q: What is changing in the EC2 Spot limits?

Amazon EC2 is transitioning Spot Instance limits from the current instance-based limits to the new vCPU-based limits to simplify the limit management experience for customers. Usage toward the vCPU-based limit is measured in terms of the number of vCPUs (virtual central processing units) for the Amazon EC2 Instance Types to launch any combination of instance types that meet your application needs.

Q: What are vCPU-based limits?

Amazon EC2 measures usage towards each limit based on the total number of vCPUs that are assigned to the Spot Instances in your Amazon Web Services account. The following table shows the number of vCPUs for each instance size. The vCPU mapping for some instance types may differ; see Amazon EC2 Instance Types for details.  

Q: How many Spot Instances can I run?

There are six vCPU-based instance limits, each defines the amount of capacity you can use of a given instance family group. All usage of instances in a given family group, regardless of generation, size, or configuration variant (e.g. disk, processor type), will accrue towards the group’s total vCPU limit, listed in the table below. New Amazon Web Services accounts may start with limits that are lower than the limits described here.

Q: Are these Spot Instance vCPU-based limits regional?

Yes, the Spot Instance limits for an Amazon Web Services account are set on a per Region basis.

Q: Will these limits change over time?

Yes, limits can change over time. Amazon EC2 is constantly monitoring your usage within each Region and your limits are raised automatically based on your use of EC2.

Q: How can I request a limit increase?

Even though EC2 automatically increases your Spot Instance limits based on your usage, if needed you can request a limit increase from the Limits Page on Amazon EC2 console.

Q: How can I calculate my new vCPU limit?

You can find the vCPU mapping for each of the Amazon EC2 Instance Types to compute the total vCPU limit requirements for your Amazon Web Services account.

Q: Do Spot vCPU limits apply when purchasing Reserved Instances or requesting On-Demand Instances?

No, the vCPU-based limits only apply to requested Spot Instances. On-Demand has independent vCPU-based limits.

Q: How can I view my current Spot Instance limits?

You can find your current Spot Instance limits on the EC2 Service Limits page in the Amazon EC2 console.

Q: Will this affect running instances?

No, vCPU-based limits will not affect any running instances.

Q: Can I still launch the same number of instances?

Yes, the vCPU-based instance limits allow you to launch at least the same number of instances as the previous instance-based limits.

Q: Will the vCPU limits have an impact on my monthly bill?

No. EC2 usage is still calculated either by the hour or the second, depending on which AMI you're running and the instance type and size you’ve launched.

Q: Will vCPU limits be available in all Regions?

vCPU-based instance limits are available in Amazon Web Services China (Beijing) Region, operated by Sinnet, and Amazon Web Services China (Ningxia) Region, operated by NWCD

Q. What price will I pay for a Spot instance?

You pay the Spot price that’s in effect at the beginning of each instance-hour for your running instance. If Spot price changes after you launch the instance, the new price is charged against the instance usage for the subsequent hour.

Q. What is a Spot capacity pool?

A Spot capacity pool is a set of unused EC2 instances with the same instance type, operating system, Availability Zone, and network platform (EC2-Classic or EC2-VPC). Each spot capacity pool can have a different price based on supply and demand.

Q. What are the best practices to use Spot instances?

We highly recommend using multiple Spot capacity pools to maximize the amount of Spot capacity available to you. EC2 provides built-in automation to find the most cost-effective capacity across multiple Spot capacity pools using Spot Fleet. For more information, please see using Spot instances.

Q. How can I determine the status of my Spot request?

You can determine the status of your Spot request via Spot Request Status code and message. You can access Spot Request Status information on the Spot Instance page of the EC2 console of the Amazon Web Services Management Console, API and CLI. For more information, please visit the Amazon EC2 Developer guide.

Q. Are Spot instances available for all instance families and sizes and in all regions?

Spot instances are available in all public Amazon Web Services regions. Spot is available for nearly all EC2 instance families and sizes, including the newest compute-optimized instances, accelerated graphics, FPGA and the new bare-metal instance types.

Q. Which operating systems are available as Spot instances?

Linux/UNIX and Windows Server are available. Windows Server with SQL Server is not currently available.

Q. Can I use a Spot instance with a paid AMI for third-party software (such as IBM’s software packages)?

Not at this time.

Q. When will my Spot instance get interrupted?

Over the last 3 months, 92% of Spot instance interruptions were from a customer manually terminating the instance because the application had completed it's work. In the circumstance, EC2 needs to reclaim your Spot instance it can be for two possible reasons, with the primary one being Amazon EC2 capacity requirements (e.g. On Demand or Reserved Instance usage). Secondarily, if you have chosen to set a “maximum Spot price” and the Spot price rises above this, your instance will be reclaimed with a two-minute notification. This parameter determines the maximum price you would be willing to pay for a Spot instance hour, and by default, is set at the On-Demand price. As before, you continue to pay the Spot market price, not your maximum price, at the time your instance was running, charged in per-second increments.

Q. How will I be charged if my Spot instance is interrupted?

If your Spot instance is terminated or stopped by Amazon EC2 in the first instance hour, you will not be charged for that usage. However, if you terminate the instance yourself, you will be charged to the nearest second. If the Spot instance is terminated or stopped by Amazon EC2 in any subsequent hour, you will be charged for your usage to the nearest second. If you are running on Windows and you terminate the instance yourself, you will be charged for an entire hour.

Q. How will I be charged if Spot price changes while my instance is running?

You will pay the price per instance-hour set at the beginning of each instance-hour for the entire hour, billed to the nearest second.

Q. Where can I see my usage history for Spot instances and see how much I was billed?

The Amazon Web Services Management Console makes a detailed billing report available which shows Spot instance start and termination/stop times for all instances. Customers can check the billing report against historical Spot prices via the API to verify that the Spot price they were billed is correct.

Q: Are Spot blocks (Fixed Duration Spot instances) ever interrupted?

Spot blocks are designed not to be interrupted and will run continuously for the duration you select, independent of Spot market price. In rare situations, Spot blocks may be interrupted due to Amazon Web Services capacity needs. In these cases, we will provide a two-minute warning before we terminate your instance (termination notice), and you will not be charged for the affected instance(s).

Q. What is a Spot fleet?

A Spot Fleet allows you to automatically request and manage multiple Spot instances that provide the lowest price per unit of capacity for your cluster or application, like a batch processing job, a Hadoop workflow, or an HPC grid computing job. You can include the instance types that your application can use. You define a target capacity based on your application needs (in units including instances, vCPUs, memory, storage, or network throughput) and update the target capacity after the fleet is launched. Spot fleets enable you to launch and maintain the target capacity, and to automatically request resources to replace any that are disrupted or manually terminated. Learn more about Spot fleets.

Q. Is there any additional charge for making Spot fleet requests?

No, there is no additional charge for Spot fleet requests.

Q. What limits apply to a Spot fleet request?

Visit the Spot Fleet Limits section of the Amazon EC2 User Guide to learn about the limits that apply to your Spot fleet request.

Q. What happens if my Spot fleet request tries to launch Spot instances but exceeds my regional Spot request limit?

If your Spot fleet request exceeds your regional Spot instance request limit, individual Spot instance requests will fail with Spot request limit exceeded bid status. Your Spot fleet request’s history will show any Spot request limit errors that the fleet request received. Visit the Monitoring Your Spot Fleet section of the Amazon EC2 User Guide to learn how to describe your Spot fleet request's history.

Q. Are Spot fleet requests guaranteed to be fulfilled?

No. Spot fleet requests allow you to place multiple Spot instance requests simultaneously, and are subject to the same availability and prices as a single Spot instance request. For example, if no resources are available for the instance types listed in your Spot Fleet request, we may be unable to fulfill your request partially or in full. We recommend you to include all the possible instance types and availability zones that are suitable for your workloads in the Spot Fleet.

Q. Can I submit a multi-Availability Zone fleet request?

Yes, visit the Spot Fleet Examples section of the Amazon EC2 User Guide to learn how to submit a multi-Availability Zone Spot fleet request.

Q. Can I submit a multi-region Spot fleet request?

No, we do not support multi-region fleet requests.

Q. How does Spot fleet allocate resources across the various Spot instance pools specified in the launch specifications?

The RequestSpotFleet API provides two allocation strategies: lowestPrice and diversified. The lowestPrice strategy allows you to provision your Spot Fleet resources in instance pools that provide the lowest price per unit of capacity at the time of the request. The diversified strategy allows you to provision your Spot Fleet resources across multiple Spot instance pools. This enables you to maintain your fleet’s target capacity and increase your application’s availability as Spot capacity fluctuates.

Running your application’s resources across diverse Spot instance pools also allows you to further reduce your fleet’s operating costs over time. Visit the Amazon EC2 User Guide to learn more.

Q. Can I tag a Spot fleet request?

You can request to launch Spot instances with tags via Spot Fleet. The Fleet by itself cannot be tagged.

Q. How can I see which Spot fleet owns my Spot instances?

You can identify the Spot instances associated with your Spot fleet by describing your fleet request. Fleet requests are available for 48 hours after all its Spot instances have been terminated. See the Amazon EC2 User Guide to learn how to describe your Spot fleet request.

Q. Can I modify my Spot fleet request?

Currently, you can only modify the target capacity of your Spot fleet request. You may need to cancel the request and submit a new one to change other request configuration parameters.

Q. Can I specify a different AMI for each instance type that I want to use?

Yes, simply specify the AMI you’d like to use in each launch specification you provide in your Spot fleet request.

Q. Can I use Spot fleet with Elastic Load Balancing, Auto Scaling, or Elastic MapReduce?

You can use Auto Scaling features with Spot Fleet such as target tracking, health checks, cloudwatch metrics etc and can attach instances to your Elastic load balancers (both classic and application load balancers). Elastic MapReduce has a feature named “Instance fleets” that provides capabilities similar to Spot Fleet.

Q. Does a Spot fleet request terminate Spot instances when they are no longer running in the lowest priced Spot pools and relaunch them in the lowest priced pools?

No, Spot fleet requests do not automatically terminate and re-launch instances while they are running. However, if you terminate a Spot instance, Spot fleet will replenish it with a new Spot instance in the new lowest priced pool.