During every backup session, Veeam Backup for Microsoft Azure creates a cloud-native snapshot for each Azure VM added to the backup policy. The cloud-native snapshot itself is a collection of point-in-time snapshots of virtual disks that Veeam Backup for Microsoft Azure takes using native Microsoft Azure capabilities.
A sequence of cloud-native snapshots created during a set of backup sessions makes up a snapshot chain. Veeam Backup for Microsoft Azure creates the snapshot chain in the following way:
- During the first backup session, Veeam Backup for Microsoft Azure creates a snapshot of all Azure VM data and saves it in the Azure region where the processed Azure VM 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 Microsoft Azure copies the whole image of the Azure VM.
- During subsequent backup sessions, Veeam Backup for Microsoft Azure creates snapshots with 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 Microsoft Docs.
Cloud-native snapshots act as independent restore points for a backed-up Azure VM. 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 Azure VM, the backup policy that created the snapshot, and a number of snapshots in the chain. Veeam Backup for Microsoft Azure uses metadata to identify outdated snapshots and apply retention policy, load the configuration of a source Azure VM during recovery operations and so on.
You can define the number of snapshots that must be retained in a snapshot chain in section Creating Backup Policies (step 6).