EC2 and RDS Snapshot Chain
During every backup session, Veeam Backup for AWS creates a cloud-native snapshot for each instance added to the backup policy. The cloud-native snapshot itself is a collection of point-in-time 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 instance data and saves it in the AWS Region where the processed instance resides. This snapshot becomes a starting point of the snapshot chain.
The creation of the first snapshot may take significant time to complete since Veeam Backup for AWS copies the whole image of the instance.
- During subsequent backup sessions, Veeam Backup for AWS takes snapshots of only those data blocks that have changed since the previous backup session.
The creation of subsequent snapshots typically takes less time to complete, compared to the first snapshot in the chain. Note, however, that the completion time still depends on the amount of processed data.
For more information on how incremental snapshots work, see AWS Documentation.
Each cloud-native snapshot in the snapshot chain contains metadata. Metadata stores information about the protected instance, the backup policy that created the snapshot, and the total number of snapshots in the chain. Veeam Backup for AWS uses metadata to identify outdated snapshots, to load the configuration of source instances during recovery operations, and so on.
Cloud-native snapshots act as independent restore points for backed-up instances. If you remove any snapshot, it will not break the snapshot chain — you will still be able to roll back instance data to any existing restore point.
The number of cloud-native snapshots kept in a snapshot chain is defined by retention policy settings. For details, see Snapshot Retention.
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 section Managing Backed-Up Data.
Snapshot replicas are copies of cloud-native snapshots 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 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.