Amazon EBS Snapshots
You can back up the data on your 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. When you delete a snapshot, only the data unique to that snapshot is removed. Active snapshots contain all of the information needed to restore your data (from the time the snapshot was taken) to a new EBS volume.
When you create an EBS volume, you can create it based on an existing snapshot. The new volume begins as an exact replica of the original volume that was used to create the snapshot. When you create a volume from an existing snapshot, it loads lazily in the background so that you can begin using them right away. If you access a piece of 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 Creating an Amazon EBS Snapshot.
By modifying their access permissions, snapshots can be shared across AWS accounts. You can make copies of your own snapshots as well as snapshots that have been shared with you. For more information, see Sharing an Amazon EBS Snapshot.
EBS snapshots broadly support EBS encryption:
Snapshots of encrypted volumes are automatically encrypted.
Volumes that are created from encrypted snapshots are automatically encrypted.
When you copy an unencrypted snapshot that you own, you can encrypt it during the copy process.
When you copy an encrypted snapshot that you own, you can reencrypt it with a different key during the copy process.
Snapshots are constrained to the region in which they are created. After you have created
a snapshot of an EBS volume, you can use it to create new volumes in the same region. For more
information, see Restoring an Amazon EBS Volume from a Snapshot.
You can also copy snapshots across regions, making it easier to leverage multiple regions for
geographical expansion, data center migration, and disaster recovery. You can copy any
accessible snapshots that have a
completed status. For more information, see
Copying an Amazon EBS Snapshot.