NVP vProxy: How often should full backups be run for VM backups with vProxy

NetWorker VMware Protection (NVP) supports 'forever incremental' however the question of if it is advisable to run full backups sometimes was recently raised.

Schedule only incremental backups for NetWorker backup actions protecting VMware Virtual Machines (VM). The NVP vProxy leverages VMware Change Block Tracking (CBT) and converts incremental backups to full using Data Domain’s virtual synthesis.

The proxy provides you with an option to perform the backup optimized for capacity and performance. The default option is Capacity, which prioritizes duplication and space utilization on the Data Domain. If you select Performance, vProxy prioritizes speed during backup. This may increase space usage on the Data Domain. The NetWorker VMware Integration Guide provides more detail on this, available on the Dell Support NetWorker Product page. 

The first backup of a VM enables Change Block Tracking (CBT) for that particular VM. Unless the VMware Administrator has a policy or a mechanism to disable CBT; however, this is apparent in a backup warning.

Incremental Uses the previous backup and leverages changed block tracking to write-only incremental blocks to a new backup that is independent of other backups. CBT is a VMware feature, not part of vProxy. Dell uses VMware’s CBT to speed up backups and improve efficiency. If CBT is disabled on the virtual machine, then it attempts to enable CBT automatically. After you add a disk to a VM, the next backup runs a full for the new disk and an incremental for the existing ones.
 
Deduplicated data always has an impact on restore operations. Deduplicated data must rehydrate during the restore. The more data is deduplicated, the more processing and overhead is required to rehydrate the data. Choosing capacity-based backup increases deduplication. Restore performance may be slower compared to performance-based backups.

Dell does not recommend scheduling full backups for VMware VMs. Backup administrators may choose to do so based on specific needs. Scheduling full backups may slow job completion and increase Data Domain disk usage. Consider these impacts before choosing this option.