Image-Level Backup Behavior

When running SLA-based backup policies, Veeam Backup for AWS produces image-level backups differently depending on whether snapshot and backup session runs overlap.

Reusing Snapshots

When a snapshot session run overlaps with a backup session run, Veeam Backup for AWS re-uses cloud-native snapshots created by the snapshot session instead of taking a new cloud-native snapshot for every backup session. The retention of these snapshots depends on whether you enable the changed block tracking (CBT) mechanism for these templates:

If CBT is enabled, Veeam Backup for AWS keeps the cloud-native snapshot used as a source for image-level backup in the snapshot chain until the next image-level backup session completes. In this case, Veeam Backup for AWS processes only those data blocks that have changed since the previous snapshot was created. This allows you to increase the speed and efficiency of incremental backups but can incur additional costs of storing snapshots in AWS.
If CBT is disabled, Veeam Backup for AWS keeps the cloud-native snapshot used as a source for image-level backup in the snapshot chain according to the retention settings specified while creating SLA templates. In case this snapshot is removed from the snapshot chain before the next backup session runs, Veeam Backup for AWS processes not only those data blocks that have changed since the previous snapshot was created, but also all other data blocks of the snapshot. This allows you to reduce the cost of storing snapshots in AWS but decreases the speed and efficiency of incremental backups.

Creating Temporary Snapshots

When a snapshot session run does not overlap with a backup session run, Veeam Backup for AWS takes temporary snapshots to be used as a source for image-level backup and then automatically removes them. The retention of these temporary snapshots depends on whether you enable the changed block tracking (CBT) mechanism for these templates:

If CBT is enabled, Veeam Backup for AWS creates a temporary snapshot and keeps it until the next image-level backup session runs. In this case, Veeam Backup for AWS processes only those data blocks that have changed since the previous snapshot was created. This allows you to increase the speed and efficiency of incremental backups but can incur additional costs of storing snapshots in AWS.
If CBT is disabled, Veeam Backup for AWS creates a temporary snapshot and removes it after the image-level backup session completes. In this case, Veeam Backup for AWS processes not only those data blocks that have changed since the previous snapshot was created, but also all other data blocks of the snapshot. This allows you to reduce the cost of storing snapshots in AWS but decreases the speed and efficiency of incremental backups.

Therefore, it is recommended that you take into account both backup schedules and your cost management strategy when choosing whether to enable CBT for SLA templates.

Important

It is not recommended that you remove temporary snapshots from AWS manually.