Reset CBT (4038674)

Reset CBT

There is a requirement to reset CBT

There are some circumstances in which CBT reset will be required, like:

- CBT fails to identify the information about the changed data blocks on the disk/s due to being reset after Storage vMotion. This results in the backup tool being unaware which blocks have changed since the last backup.
- An incremental virtual machine backup is not possible and a full backup is required.
- You get an error message like: CBT failed or CBT data is invalid or Cannot use CBT

The following steps should be followed in order to reset CBT information on the Virtual Machine. All of these steps should be followed on the vSphere Client:

- Power OFF the VM.
- Right click the VM, click “Edit Settings”, click on “Options” tab.
- Under “Advanced”, click “General” and then click on “Configuration Parameters…” button.

- In a new Pop-up called “Configuration Parameters”, all Name-Value pairs will appear. Locate “ctkEnabled” and set it’s value to “false”.

- Also locate “scsix:y.ctkEnabled” and set it’s value to “false” for each of the disks belonging to that VM.

- Go to the Datastore where the VM files are located. Remove any “*.ctk.vmdk” files. If the VMDKs for that VM are in more than 1 Datastores, then look for the above type of file in those Datastores and delete those also.

- Now, power ON the VM.
- After it’s booted, power it OFF. NOTE: This step is needed to update the CTK Table for the VM.
- Power ON the VM again.
- Whenever the next backup of the VM is run, CBT will get enabled and Incremental/Differential Backups for this VM will start working as intended.