VMware recently released a notice about a bug that’s been around since VMware 4.0. If you’ve ever had a failed restore and couldn’t figure out why, it might be because of that bug.
Learn more about the VMware CBT bug.
Luckily, Veeam released a workaround for VMware’s CBT bug in their most recent v8 release. Basically, jobs now reset CBT on a virtual machine (VM) upon detecting any virtual disk configuration change. What this means, practically, is that if you make a virtual disk change to a VM, you can expect the next backup to take longer than it normally would.
If there have been any changes in the past, it’s not going to provide a fix for them. You will still have to manually reset CBT on VMs that have been expanded in the past.
For a good source of alternative scripts as well as answers to all possible related questions visit this Veeam forum thread.