Proxmox VE VM Did Not Provide Valid CBT Data

Product version: 11.0

Last modified: 11 September 2024

Problem

An error message states that the Proxmox VE VM did not provide valid CBT data.

Background

  1. If the VM image is stored in the QEMU format, the dirty bitmap (CBT) is persistent and the VM restart does not affect CBT (available to continue conducting incremental backups).

  2. If the VM image is stored in the RAW or VMDK format, the non-persistent dirty bitmap is used and the VM restart leads to dirty bitmap reset and the next backup uses the Poprietary change tracking method to create incremental backups.

Solution

  • Don't restart the VM image that is stored in the RAW or VMDK format non-persistent (limitation).

  • Perform initial (full) backup/replication for the VM (this step creates a new dirty bitmap) and the next run runs CBT normally.

  • Switch to the Proprietary method in case of a CBT failure:

    1. Run the backup with CBT by switching to use the Proprietary method (this step creates a new dirty bitmap).

    2. The next run shall use the CBT to run normally.