Changed Block Tracking for VMware Backups

Changed Block Tracking (CBT) is a VMware feature that optimizes backup procedures to back up only changed blocks during incremental backup plan runs.

Enable Changed Block Tracking in Backup Plans

Changed Block Tracking feature can be enabled for any virtual machine backup plan. To learn how to enable it, refer to the VMware and Hyper-V Backup chapter.

Changed Block Tracking Explained

Changed Block Tracking identifies the disk sectors modified between two changeset stamps.

On VMFS partitions, CBT can also identify all the disk sectors that are in use.

Changed blocks of virtual disk are tracked on the virtualization layer. During incremental runs the backup plan only process blocks that have been changed since the last backup and blocks in use.

For more information about the feature refer to VMware documentation

Enable Changed Block Tracking

To enable Changed Block Tracking, proceed as follows:

  1. Create or edit the VMware backup plan. If you create a new backup plan, you will be prompted to enable the Changed Block Tracking feature in the beginning.
  2. Follow the backup wizard step to the Select Virtual Machines step.
  3. Select virtual machines to back up, then select the Use Changed Block Tracking check box to apply the changed block tracking feature. In most cases, this feature increases the backup speed

  1. Click Next.
  2. Follow the backup wizard steps to save the backup plan configuration.