Services or capabilities described in Amazon Web Services documentation might vary by Region. To see the differences applicable to the China Regions, see Getting Started with Amazon Web Services in China (PDF).

Amazon EBS snapshots

You can back up the data on your Amazon EBS volumes to Amazon S3 by taking point-in-time snapshots. Snapshots are incremental backups, which means that only the blocks on the device that have changed after your most recent snapshot are saved. This minimizes the time required to create the snapshot and saves on storage costs by not duplicating data.

Each snapshot contains all of the information that is needed to restore your data (from the moment when the snapshot was taken) to a new EBS volume. When you create an EBS volume based on a snapshot, the new volume begins as an exact replica of the original volume that was used to create the snapshot. The replicated volume loads data in the background so that you can begin using it immediately. If you access data that hasn't been loaded yet, the volume immediately downloads the requested data from Amazon S3, and then continues loading the rest of the volume's data in the background. For more information, see Create Amazon EBS snapshots.

When you delete a snapshot, only the data unique to that snapshot is removed. For more information, see Delete an Amazon EBS snapshot.

Snapshot events

You can track the status of your EBS snapshots through CloudWatch Events. For more information, see EBS snapshot events.

Application-consistent snapshots

Using Systems Manager Run Command, you can take application-consistent snapshots of all EBS volumes attached to your Amazon EC2 Windows instances. The snapshot process uses the Windows Volume Shadow Copy Service (VSS) to take image-level backups of VSS-aware applications, including data from pending transactions between these applications and the disk. You don't need to shut down your instances or disconnect them when you back up all attached volumes. For more information, see Creating a VSS Application-Consistent Snapshot.

Multi-volume snapshots

Snapshots can be used to create a backup of critical workloads, such as a large database or a file system that spans across multiple EBS volumes. Multi-volume snapshots allow you to take exact point-in-time, data coordinated, and crash-consistent snapshots across multiple EBS volumes attached to an EC2 instance. You are no longer required to stop your instance or to coordinate between volumes to ensure crash consistency, because snapshots are automatically taken across multiple EBS volumes. For more information, see the steps for creating a multi-volume EBS snapshot under Create Amazon EBS snapshots .

Snapshot pricing

Charges for your snapshots are based on the amount of data stored. Because snapshots are incremental, deleting a snapshot might not reduce your data storage costs. Data referenced exclusively by a snapshot is removed when that snapshot is deleted, but data referenced by other snapshots is preserved. For more information, see Amazon Elastic Block Store Volumes and Snapshots in the Amazon Billing User Guide.

How snapshots work

The first snapshot that you create from a volume is always a full snapshot. It includes all of the data blocks written to the volume at the time of creating the snapshot. Subsequent snapshots of the same volume are incremental snapshots. They include only changed and new data blocks written to the volume since the last snapshot was created

The size of a full snapshot is determined by the size of the data being backed up, not the size of the source volume. Similarly, the storage costs associated with a full snapshot is determined by the size of the snapshot, not the size of the source volume. For example, you create the first snapshot of a 200 GiB Amazon EBS volume that contains only 50 GiB of data. This results in a full snapshot that is 50 GiB in size, and you are billed for 50 GiB snapshot storage.

Similarly, the size and storage costs of an incremental snapshot are determined by the size of any data that was written to the volume since the previous snapshot was created. Continuing this example, if you create a second snapshot of the 200 GiB volume after changing 20 GiB of data and adding 10 GiB of data, the incremental snapshot is 30 GiB in size. You are then billed for that additional 30 GiB snapshot storage.

For more information about snapshot pricing, see Amazon EBS pricing.

The following sections show how an EBS snapshot captures the state of a volume at a point in time, and how subsequent snapshots of a changing volume create a history of those changes.

Multiple snapshots of the same volume

The diagram in this section shows Volume 1, which is 15 GiB in size, at three points in time. A snapshot is taken of each of these three volume states. The diagram specifically shows the following:

Incremental snapshots of different volumes

The diagram in this section shows how incremental snapshots can be taken from different volumes.

For more information about how data is managed when you delete a snapshot, see Delete an Amazon EBS snapshot.

Copy and share snapshots

You can share a snapshot across Amazon accounts by modifying its access permissions. You can make copies of your own snapshots as well as snapshots that have been shared with you. For more information, see Share an Amazon EBS snapshot.

A snapshot is constrained to the Amazon Region where it was created. After you create a snapshot of an EBS volume, you can use it to create new volumes in the same Region. For more information, see Create a volume from a snapshot. You can also copy snapshots across Regions, making it possible to use multiple Regions for geographical expansion, data center migration, and disaster recovery. You can copy any accessible snapshot that has a completed status. For more information, see Copy an Amazon EBS snapshot.

Encryption support for snapshots

EBS snapshots fully support EBS encryption.

Complete documentation of possible snapshot encryption scenarios is provided in Create Amazon EBS snapshots and in Copy an Amazon EBS snapshot.

For more information, see Amazon EBS encryption.