Backup Chain and Retention Policy
For backups of RHV VMs, Veeam Backup for RHV implements the forever forward incremental and forward incremental backup methods. For more information, see the Backup Methods section of the Veeam Backup & Replication User Guide.
To back up RHV VMs, you must configure a backup job in the Veeam Backup for RHV web console.
During the first backup session, Veeam Backup for RHV copies the whole content of the VM and creates a full backup file (VBK) in the repository. The full backup file acts as a starting point of the backup chain.
During the second and further backup sessions, Veeam Backup for RHV copies only those data blocks that have changed since the previous backup session. Changed data blocks are stored as an incremental backup file in the repository. Incremental backup files depend on the full backup file and preceding incremental backup files of the backup chain. In the backup job settings, you can also enable periodic creation of active full backups.
One backup job can be used to process one or several VMs. Veeam Backup for RHV creates per-VM backup chains: one backup chain contains data for one VM only. Even if you add several VMs to the backup job, Veeam Backup for RHV creates several backup chains on the backup repository, one per each VM processed by the job.
You can instruct Veeam Backup for RHV to run jobs automatically according to a specified schedule or you can start them manually.
Backup jobs and backup files created by Veeam Backup for RHV are visible in the Veeam Backup & Replication console. However, some of the Veeam Backup & Replication functionality is not available for backups of RHV VMs. For more information, see Backup Job Limitations.
Changed Block Tracking (CBT)
When Veeam Backup for RHV performs incremental backup, it needs to know what data blocks have changed since the previous job session. To get the list of changed data blocks, Veeam Backup for RHV uses the RHV changed block tracking mechanism (CBT). CBT increases the speed and efficiency of incremental backups.
RHV CBT uses REST API to determine the changed metadata regions in RHV virtual disks. CBT compares two checkpoints: a checkpoint of the current virtual disks environment with the checkpoint that was obtained during the previous backup. Only the changed metadata regions that the API detects are backed up and written to backup repository. After the backup completes, the current checkpoint will become the previous checkpoint for comparison in the next backup operation. Only one snapshot per VM will be retained for comparison.
Every successful backup job session creates a new restore point that lets you roll back VM data to an earlier point in time. To control the number of restore points in the backup chain, you must specify retention policy settings. The retention policy defines how many restore points you want to retain on disk and thus how ‘far’ you are able to roll back. After the allowed number of restore points is exceeded, Veeam Backup for RHV automatically removes the earliest restore point from the backup chain.
To define the retention policy for a backup job, you must specify the necessary number of restore points in the Restore points to keep field in the backup job settings. By default, Veeam Backup for RHV keeps 7 restore points. In the Schedule step of the New Job wizard you can select the following units of retention policy.
For more information on the retention policy for RHV VM backups, see the Forward Incremental Backup Retention Policy section of the Veeam Backup & Replication User Guide.
Active Full Backup
In some cases, you need to regularly create full backups. For example, your corporate backup policy may require that you create a full backup on weekend and run incremental backup on work days. To let you conform to these requirements, Veeam Backup for RHV lets you create active full backups.
The active full backup produces a full backup of a VM, just as if you run the backup job for the first time. Veeam Backup for RHV retrieves data for the whole VM from the source, compresses and deduplicates it and stores it to the full backup file — VBK.
The active full backup resets a backup chain. All incremental backup files use the latest active full backup file as a new starting point. A previously used full backup file remains on disk until it is automatically deleted according to the retention policy.
You can create active full backups manually or schedule a backup job to create active full backups periodically.
- To create an active full backup manually, see Creating Active Full Backup.
- To schedule active full backups, specify scheduling settings in the Advanced section of a corresponding backup job. You can schedule active full backups to run weekly, for example, every Saturday, or monthly, for example, every fourth Sunday of a month. For more information, see Specify Repository.