Problem Description
Backup of a VMware virtual machine (VM) fails with the error VMWARE_VMOMI65535.
Cause
This issue occurs when the VM is configured with one or more multi-writer disks while Changed Block Tracking (CBT) is enabled.
VMware does not support CBT for virtual machines that have multi-writer disks attached. As a result, backup operations that rely on CBT fail.
Traceback
The backup job fails with error VMWARE_VMOMI65535.
The detailed backup logs contain an error similar to the following:
[ERROR] Error <class 'pyVmomi.VmomiSupport.vmodl.fault.NotSupported'>: (vmodl.fault.NotSupported) { msg = 'The operation is not supported on the object.', faultMessage = [ message = 'CBT-enabled VM having multi-writer disk(s) is not supported' ] }
The key message indicating the root cause is:
CBT-enabled VM having multi-writer disk(s) is not supported
Verification
Download the detailed backup job logs.
Search for the following message:
CBT-enabled VM having multi-writer disk(s) is not supported
Verify in the VMware vSphere Client whether the affected VM has one or more disks configured with the Multi-Writer flag.
Resolution
Since VMware does not support CBT for VMs with multi-writer disks, disable CBT for the affected VM before running the backup.
Option 1: Disable CBT Using the Druva Backup Proxy (Recommended)
Log in to the backup proxy.
Navigate to:
/opt/Druva/EnterpriseWorkloads/lib/Run the following command:
vmcontrol disable_cbt <VM_Name>Replace
<VM_Name>with the name of the affected virtual machine.
Create or update the backup policy assigned to the VM and ensure CBT is disabled for that policy.
Trigger a manual backup to verify the issue is resolved.
Option 2: Disable CBT from VMware vSphere
Disable CBT for the affected VM using the VMware vSphere Client, then trigger a new backup.