| KB ID: | 4208 |
Challenge
A backup job for a Red Hat Virtualization VM was unable to enable incremental backup support. The following warning occurs:
Unable to enabled ovirt incremental backups for disk '':. Full scan backups will be performed. Please see KBxxxxx for more informationSolution
Here are the two most common causes of this issue and how to resolve them.
Cause: Incremental Backup Support is disabled at the system level
After upgrade Red Hat Virtualization from older versions, incremental backup support may be disabled at the system level.
Solution:
- Connect to the ovirt-engine system via ssh
- Execute the following commands:
engine-config -s "IsIncrementalBackupSupported=true"
systemctl restart ovirt-engineCause: VM Disk created without Incremental Backup support
When creating a VM disk, if the option for 'Enable Incremental Backup' is not enabled, the disk will be created in RAW format and won't support incremental backups. After the disk has been created, the 'Enable Incremental Backup' option will be greyed out and cannot be enabled.
Solution:
There are two methods to resolve this limitation.
- (Recommended) Create a snapshot of the VM. Then, edit the disk and enable the Incremental Backup option.
Note: The snapshot must remain in place. If it is removed, the Incremental Backup option will become disabled. In the long term, you should rebuild the VM/disk to have Incremental Backup enabled on the disk at the time of creation.
- Convert the disk from RAW to QCOW2 using the qemu-img utility.
Please use official documentation
https://qemu.readthedocs.io/en/latest/tools/qemu-img.html.
This method is not recommended as the conversion process can be time-consuming, and there is a risk of data loss.