# Kubernetes Changed Block Tracking API - Beta Differences

DevFeed: [Kubernetes Changed Block Tracking API - Beta Differences](<https://devfeed.tech/articles/kubernetes-changed-block-tracking-api-beta-differences-20862.md>)

Original publisher: [Read original article](<https://kubernetes.io/blog/2026/09/14/csi-changed-block-tracking-beta/>)

Author: Prasad Ghangal

Published: 2026-09-14T18:30:00Z

Content type: article

Language: en

Sources: [Kubernetes Blog](<https://devfeed.tech/sources/kubernetes-blog.md>)

Topics: [Kubernetes](<https://devfeed.tech/topics/kubernetes.md>), [API](<https://devfeed.tech/topics/api.md>), [gRPC](<https://devfeed.tech/topics/grpc.md>)

Tags: [2026](<https://devfeed.tech/tags/2026.md>), [compatibility](<https://devfeed.tech/tags/compatibility.md>), [container-image-registry](<https://devfeed.tech/tags/container-image-registry.md>), [developer](<https://devfeed.tech/tags/developer.md>), [documentation](<https://devfeed.tech/tags/documentation.md>), [kubernetes](<https://devfeed.tech/tags/kubernetes.md>), [registry](<https://devfeed.tech/tags/registry.md>), [release](<https://devfeed.tech/tags/release.md>), [snapshots](<https://devfeed.tech/tags/snapshots.md>), [storage](<https://devfeed.tech/tags/storage.md>), [streaming](<https://devfeed.tech/tags/streaming.md>), [update](<https://devfeed.tech/tags/update.md>)

## AI overview

This Kubernetes developer article explains the Beta changes to Changed Block Tracking (CBT) support for CSI drivers. The SnapshotMetadataService CRD moved from v1alpha1 to v1beta1, with no automatic conversion, and CBT remains limited to block volumes. It also outlines compatibility requirements and the steps for upgrading and trying the feature.

## Source excerpt

Changed Block Tracking (CBT) support for CSI drivers shipped as Alpha in September 2025. With the March 2026 v1.0.0 release of the external-snapshot-metadata project, the feature moved to Beta. If you aren't yet familiar with changed block tracking for storage in Kubernetes, the Alpha announcement covers the motivation, the three primary components (the CSI SnapshotMetadata gRPC service, the SnapshotMetadataService CRD, and the external-snapshot-metadata sidecar), and a walkthrough of how to use the API. CBT currently applies to block volumes; file-volume and network file-share changed-list tracking is not covered by this feature. This post focuses on what is different in Beta. What's new in Beta The main change in that release was the promotion of the SnapshotMetadataService CRD from v1alpha1 to v1beta1. The CRD used to advertise a driver's metadata service now serves cbt.storage.k8s.io/v1beta1. The schema itself is unchanged, but this release removed v1alpha1 (rather than serving it alongside the new version). If you are upgrading from Alpha, you need to: Re-apply the CRD definition shipped with v1.0.0. Update SnapshotMetadataService manifests to use apiVersion: cbt.storage.k8s.io/v1beta1. Update any client or controller code that talks to the CRD. This is a one-time change. There is no automatic conversion between the two versions. Compatibility Minimum Kubernetes version: 1.33 CSI spec: 1.10 or newer Container image: registry.k8s.io/sig-storage/csi-snapshot-metadata:v1.0.0 Trying it out The Getting Started section in the Alpha blog still applies. In short: Make sure your CSI driver supports volume snapshots and ships the external-snapshot-metadata sidecar. Install the SnapshotMetadataService CRD (the v1beta1 definition from the v1.0.0 release). Create a SnapshotMetadataService resource for your driver. Use a client -- snapshot-metadata-lister, or your own implementation -- to call GetMetadataAllocated and GetMetadataDelta. If you want to see the full flow end-to-e