Configure Windows fast launch for your Windows Server AMI - Amazon Elastic Compute Cloud
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Configure Windows fast launch for your Windows Server AMI

Every Amazon EC2 Windows instance must go through the standard Windows operating system (OS) launch steps, which include several reboots, and often take 15 minutes or longer to complete. Amazon EC2 Windows Server AMIs that have the Windows fast launch feature enabled complete some of those steps and reboots in advance to reduce the time it takes to launch an instance.

When you configure a Windows Server AMI for Windows fast launch, Amazon EC2 creates a set of pre-provisioned snapshots to use for faster launching, as follows.

  1. Amazon EC2 launches a set of temporary t3 instances, based on your settings.

  2. As each temporary instance completes the standard launch steps, Amazon EC2 creates a pre-provisioned snapshot of the instance. It stores the snapshot in your Amazon S3 bucket.

  3. When the snapshot is ready, Amazon EC2 terminates the associated t3 instance to keep resource costs as low as possible.

  4. The next time Amazon EC2 launches an instance from the Windows fast launch enabled AMI, it uses one of the snapshots to significantly reduce the time it takes to launch.

Amazon EC2 automatically replenishes the snapshots you have on hand as it uses them to launch instances from the Windows fast launch enabled AMI.


Any account that has access to an AMI with Windows fast launch enabled can benefit from reduced launch times. However, it's the AMI owner's account that provides the snapshots that Windows fast launch consumes for the launch.

This feature is not the same as EBS fast snapshot restore. You must explicitly enable EBS fast snapshot restore on a per-snapshot basis, and it has its own associated costs.

The following video demonstrates how to configure your Windows AMI for faster launching with a quick overview of the related key terms and their definitions: Launching EC2 Windows instances up to 65% faster on Amazon.

Resource costs

There is no service charge to configure Windows AMIs for Windows fast launch. However, standard pricing applies for any underlying Amazon resources that Amazon EC2 uses. To learn more about associated resource costs and how to manage them, see Manage resource costs.

Key terms

The Windows fast launch feature uses the following key terms:

Pre-provisioned snapshot

A snapshot of an instance that was launched from a Windows AMI with Windows fast launch enabled, and that has completed the following Windows launch steps, rebooting as required.

  • Sysprep specialize

  • Windows Out of Box Experience (OOBE)

When these steps are complete, Windows fast launch stops the instance, and creates a snapshot that is later used for faster launching from the AMI, based on your configuration.

Launch frequency

Controls the number of pre-provisioned snapshots that Amazon EC2 can launch within the specified timeframe. When you enable Windows fast launch for your AMI, Amazon EC2 creates the initial set of pre-provisioned snapshots in the background. For example, if the launch frequency is set to five launches per hour, which is the default, then Windows fast launch creates an initial set of five pre-provisioned snapshots.

When Amazon EC2 launches an instance from an AMI with Windows fast launch enabled, it uses one of the pre-provisioned snapshots to reduce the launch time. As snapshots are used, they are automatically replenished, up to the number specified by the launch frequency.

If you expect a spike in the number of instances that are launched from your AMI – during a special event, for example – you can increase the launch frequency in advance to cover the additional instances that you'll need. When your launch rate returns to normal, you can adjust the frequency back down.

When you experience a higher number of launches than anticipated, you might use up all the pre-provisioned snapshots that you have available. This doesn't cause any launches to fail. However, it can result in some instances going through the standard launch process, until snapshots can be replenished.

Target resource count

The number of pre-provisioned snapshots to keep on hand for an Amazon EC2 Windows Server AMI with Windows fast launch enabled.

Max parallel launches

Controls how many instances Amazon EC2 can launch at the same time to create the pre-provisioned snapshots for Windows fast launch. If your target resource count is higher than the maximum parallel launches that you've configured, then Amazon EC2 launches the number of instances specified by Max parallel launches to start creating the snapshots. As those instances complete the process, Amazon EC2 takes the snapshot and stops the instance. Then it continues to launch more instances until the total number of snapshots available has reached the target resource count. The value for Max parallel launches must be 6 or greater.