Snapshot Chain

During every backup session, Veeam Backup for Google Cloud creates a cloud-native snapshot of each instance (whether it is a VM instance or a Cloud SQL instance) added to a backup policy. The cloud-native snapshot itself is a collection of point-in-time snapshots that Veeam Backup for Google Cloud creates using native Google Cloud capabilities.

A sequence of cloud-native snapshots created during a set of backup sessions makes up a snapshot chain. Veeam Backup for Google Cloud builds the snapshot chain in the following way:

  1. During the first backup session, Veeam Backup for Google Cloud creates a snapshot of all instance data and saves it in the region in which the processed instance resides. This snapshot becomes a starting point in the snapshot chain.

The creation of the first snapshot may take significant time to complete since Veeam Backup for Google Cloud copies the whole image of the instance.

  1. During subsequent backup sessions, Veeam Backup for Google Cloud creates snapshots that contain 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 VM and Cloud SQL snapshots work, see Google Cloud Compute Engine documentation and Google Cloud SQL documentation.

Each cloud-native snapshot in the snapshot chain contains metadata. Metadata stores information about the protected instance and the backup policy that created the snapshot. Veeam Backup for Google Cloud uses metadata to identify outdated snapshots, to load the configuration of source instances during recovery operations, and so on.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.

Snapshot Chain 

The number of cloud-native snapshots kept in the snapshot chain is defined by retention policy settings. For more information, see Retention Policy for Snapshots.