Snapshots are an integral part of Amazon Elastic Block Store (EBS). Snapshots allow you to create a block-level, point-in-time copy of your volumes for backup, or disaster-recovery purposes. Snapshots are incremental, only data modified since the last snapshots are copied again. You can share snapshots between AWS Regions, or AWS Accounts. Once you have a snapshot, you can create a new Amazon Elastic Block Store (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.
When you restore volumes from snapshots, they are available for use almost instantaneously. In the background, EBS lazy loads the data from the snapshot as the operating systems accesses the blocks, this reduces the I/O performance of the volume until it is fully initialized. Some I/O demanding workloads however need the volume to operate at full capacity as soon as it is available. This is why we introduced Fast Snapshot Restore (FSR). Once enabled, FSR allows to create volumes that deliver their maximum performance and do not need to be initialized.
Many AWS customers are sharing their snapshots with other AWS Accounts, and there are many reasons to do this. You might want to centrally prepare and manage golden AMIs, with your applications, monitoring, or management tools pre-backed. In the context of Disaster Recovery (DR), your company policies might require to store all backups in one dedicated account. Until today, only the AWS Account owning the snapshot could enable FSR.
Today, you can enable Fast Snasphot Restore (FSR) on snapshots shared with you.
To enable FSR on a shared snapshot, I first create a snapshot on the source AWS Account. Once the snapshot is created, I share it with another account of mine. To do so, I click Actions, and Modify Permissions. I enter the destination AWS Account Number, click Add Permission and Save.