A question about incremental backup functionality

[Raghuram Devarakonda]

HI,

The KubeVirt 1.8 release notes (https://kubevirt.io/2026/KubeVirt-v1-8-release.html) say this regarding incremental backup support:

"Incremental Backup with Changed Block Tracking (CBT) leverages QEMU’s and libvirt backup capabilities providing storage agnostic incremental VM backups. By capturing only modified data, the solution eliminates reliance on specific CSI drivers, allowing for faster backup windows and a drastically reduced storage footprint. This not only ensures storage freedom but also minimizes cluster network traffic for peak efficiency."

However, checking the status of VEP 25, it doesn't look like all the relevant PRs are merged (and some changes apparently reverted). Please correct me if I am missing something here. Given this, I am curious what CBT functionality is available in 1.8. It could be that "Push" method CBT is available but "Pull" is not but I could not tell by going through the VEP status.

Thanks in advance,

Raghu

[Natalie Gavrielov]

Hi Raghu,

Both Push mode and Pull mode CBT are present in v1.8. The full set of changes landed and backported to the release-1.8 branch, PR #17061.

The revert PR was closed, not merged.

Regards,

Natalie

[Raghuram Devarakonda]

Got it, thanks.

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[Pramodh.Pallapothu]

Hi Community,

Is there proper documentation of this feature ?  I would like to know how it works and the user level actions we need to perform.

I searched on Kubevirt docs but could not find it, maybe I am searching in the wrong place.

Thanks,

Pramodh

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[Raghuram Devarakonda]

Hi Pramodh,

You can this page for details:

    https://github.com/kubevirt/enhancements/blob/main/veps/sig-storage/incremental-backup.md

Thanks,

Raghu