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By Zayden R., September 15, 2026
Kubernetes has moved its Changed Block Tracking (CBT) API to Beta with the release of the external-snapshot-metadata project v1.0.0. Engineers should update their CRD definitions to the new API version for continued support.
Kubernetes has advanced its Changed Block Tracking (CBT) API from Alpha to Beta with the release of the external-snapshot-metadata project v1.0.0, marking a significant step for storage management within Kubernetes. This shift is crucial for engineers working with CSI drivers, as it introduces the need to update their systems to use the new API version, cbt.storage.k8s.io/v1beta1, following the removal of the v1alpha1 version.
The CBT API is designed to track changes in block storage volumes, a feature that remains exclusive to block volumes and does not yet extend to file volumes or network file-shares. The main technical change in this Beta release is the promotion of the SnapshotMetadataService Custom Resource Definition (CRD) to v1beta1. While the schema itself remains unchanged, the deprecation of the v1alpha1 version necessitates a manual update by engineers. This involves reapplying the CRD definition from the v1.0.0 release and updating SnapshotMetadataService manifests to the new API version.
For those managing CSI drivers, it is essential to ensure compatibility with Kubernetes version 1.33 or newer and CSI specification 1.10 or later. Additionally, the container image required is registry.k8s.io/sig-storage/csi-snapshot-metadata:v1.0.0. The transition to Beta also seeks to drive wider adoption and gather operational feedback, paving the way for future General Availability (GA).
Engineers looking to implement or test the updated CBT capabilities should begin by confirming their CSI driver supports volume snapshots and includes the external-snapshot-metadata sidecar. The Kubernetes blog suggests starting with a hostpath driver example to get familiar with the full implementation flow. With the API now in Beta, this is an opportune moment for developers and sysadmins to evaluate their systems and provide feedback on the functionality and performance of the CBT API.