CBT Not Enabled for VM: How to Resolve the Error and Enable CBT

Error: CBT Not Enabled for VM

KB ID: 105007
Problem:
When attempting to back up a virtual machine using BDRSuite, users may encounter an error message indicating that Changed Block Tracking (CBT) was not enabled for the VM. This prevents the successful backup of the virtual machine.
Cause:
The error message appears when CBT is not enabled for the virtual machine, which is required for the backup process to work correctly.
Solution:
To resolve the "CBT Not Enabled" error and enable CBT for the virtual machine, follow these steps:
Ensure that the following prerequisites are met:
1. The ESX/ESXi host where the virtual machine is located should be version 4.0 or later.
2. The virtual machine's hardware version should be 7 or later.
If the prerequisites are fulfilled, proceed with enabling CBT by performing the following steps:
1. Power off the virtual machine.
2. Right-click the virtual machine and select "Edit Settings."
3. Click on the "Options" tab.
4. Under the "Advanced" section, click "General," and then click "Configuration Parameters." This will open the Configuration Parameters dialog.
5. Click "Add Row" to add a new configuration parameter.
6. Add the parameter "ctkEnabled" and set its value to "true."
7. Click "Add Row" again and add "scsi0:0.ctkEnabled" as the parameter name, setting its value to "true."
Note: The "scsi0:0" part in "scsi0:0.ctkEnabled" represents the SCSI device assigned to the hard disk added to the virtual machine. If there are multiple hard disks, they will have different SCSI devices, like scsi0:1 or scsi1:1. CBT must be enabled individually for each disk.
8. Power on the virtual machine.
9. In the home directory of the virtual machine, verify that each disk with CBT enabled has a corresponding "vmname-ctk.vmdk" file.
By following these steps, CBT should be successfully enabled for the virtual machine, and the backup process using BDRSuite should work as expected.