Incremental backups using VD Service (CBT) from ESXi 6.0.X servers may be corrupted.

Cause:

This is a VMware ESXi issue in CBT logic that affects ESXi 6.0.X servers prior to patch ESXi.6.0.3247720

As described in the following VMware KB (http://kb.vmware.com/kb/2136854), the issue occurs when you run virtual machine backups which utilize Changed Block Tracking (CBT) in ESXi 6.0; the CBT API call QueryDiskChangedAreas() might return incorrect changed sectors that results in inconsistent incremental backups.

All incremental backups done from ESXi 6.0.X server prior to patch ESXi.6.0.3247720 should be considered as corrupted.

Solution:

Update all ESXi 6.0 servers to the latest available patch and replace all incremental backups previously made.
Force an initial new full backup by resetting Changed Block Tracking (CBT) of all the VMs to backup, as described in the following VMware KB: http://kb.vmware.com/kb/2139574