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

The 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 a virtual disk are tracked at the virtualization layer. During incremental runs, the backup plan processes only blocks that have been changed since the last backup and blocks in use.

For more information about the feature, refer to the VMware documentation.

Enable Changed Block Tracking

To enable Changed Block Tracking in the Management Console, proceed as follows:

1. Create or edit the VMware backup plan.
2. Follow the backup wizard steps to the Advanced Settings step.
3. Enable Advanced Settings.

4. Select the Use Changed Block Tracking checkbox to apply the changed block tracking feature. In most cases, this feature increases the backup speed.
5. Follow the backup wizard steps to save the backup plan configuration.