Premier IT Outsourcing and Support Services within the UK

User Tools

Site Tools


Enable CBT on a Virtual Machine on ESXi

Sometimes CBT (Changed Block Tracking) is required to implement a backup solution, and it can be enabled per VM and per drive.

Enabling it is not as simple as ticking a box but its easily do-able following the process below. This process is Current for ESXi 7.0.3.

This is all done via the ESXi Web Console.

  • First power off (shutdown) the virtual machine.
  • Edit Settings
  • Click VM Options
  • Click Advanced
  • Navigate to Edit Configuration and click that.

We need to add two parameters to this configuration. Clicking "Add Parameter" Creates a new one at the bottom, so do this twice.

Now for each of the newly created Parameters set them to:


Now click SAVE and then done. Start the virtual machine and CBT should be enabled.


If you have added more than one virtual hard drive to the virtual machine, you will need to add an extra parameter for each additional virtual hard drive. These additional hard drives will be scsi0:1 or scsi1:1 so you will need to identify this by looking at the "Hardware Configuration" under "Hard Disk x" - it will show something like SCSI Controller 0:1, and then create an extra line for each e.g.

/home/ · Last modified: 2022/03/16 15:57 by genadmin