During every backup session, Veeam Backup for AWS creates a cloud-native snapshot for each EC2 instance added to the backup policy. The cloud-native snapshot itself is a collection of point-in-time EBS snapshots that Veeam Backup for AWS takes using native AWS capabilities.
A sequence of cloud-native snapshots created during a set of backup sessions makes up a snapshot chain. Veeam Backup for AWS creates the snapshot chain in the following way:
- During the first backup session, Veeam Backup for AWS creates a snapshot of all EC2 instance data and saves it in the AWS region where the processed EC2 instance resides. This snapshot becomes a starting point of the snapshot chain.
Snapshot creation during the first backup session may take significant time to complete since the whole content of the EC2 instance is copied.
- Snapshots created during subsequent backup sessions store only those data blocks that have changed since the previous backup session.
Subsequent snapshots typically take less time to complete compared to the first snapshot in the chain. Note, however, that the completion time for subsequent snapshots still depends on the amount of changed data.
Cloud-native snapshots act as independent restore points for a backed-up EC2 instance. If you remove any snapshot, it will not break the snapshot chain — you will still be able to roll back your data to any existing restore point.
Each cloud-native snapshot in a snapshot chain contains metadata. Metadata includes information about the processed EC2 instance, backup policy that created the snapshot, and a number of snapshots in the chain. Veeam Backup for AWS uses metadata to identify outdated snapshots and apply retention policy, load the configuration of a source EC2 instance during recovery operations and so on.
The number of cloud-native snapshots that you want to keep in a snapshot chain is defined in retention policy settings. For details, see Retention Policy for Snapshots.
Cloud-native snapshots created manually are not included into the snapshot chain. Therefore, such snapshots are not removed automatically according to retention policy settings. For information on how to remove them, see sections Removing Backups and Removing Individual Cloud-Native Snapshots Created Manually.
Snapshot replica is a copy of a cloud-native snapshot that Veeam Backup for AWS creates during backup sessions. If you enable snapshot replication for a backup policy, Veeam Backup for AWS will make a copy of the initially created cloud-native snapshot and save it to the target AWS region specified in backup policy settings. In the target AWS region, snapshot replicas created during a set of backup sessions make up a snapshot replica chain.
Veeam Backup for AWS creates and maintains a snapshot replica chain in the same way as a regular snapshot chain:
- The first created snapshot replica for the processed EC2 instance becomes a starting point of the snapshot replica chain.
- Snapshot replicas created during subsequent backup sessions store only those data blocks that have changed since the previous backup session.