Ever since VMware ESX/ESXi 4.0 was introduced, ESX/ESXi hosts have been able to track changed disk sectors. This powerful monitoring mechanism is called Changed Block Tracking (CBT) and aims to improve the efficiency of the backup process and simplify the use of third-party VMware backup software.
Read how CBT works and how to enable this feature in VMware vSphere for incremental VM backup: https://www.nakivo.com/blog/vmware-changed-block-tracking-works
