# Rook v1.21.0

> Storage & Data · 2026-10-06

A breaking release changes Helm chart and Ceph defaults and removes automatic setup for some resources and images. It also adds storage and object-management capabilities, so chart references, kernel compatibility, new NFS installs, and custom CSI image settings may need review.

## Check if affected
- **[breaking]** Helm OCI chart tag format
  - Applies if you reference Helm OCI chart tags in scripts or tooling.
  - Helm OCI chart tags no longer include the `v` prefix, so `1.21.0` replaces `v1.21.0`. Scripts and tooling that reference charts by tag need to use the new format.
- **[breaking]** Ceph `msgrv2` default requirement
  - Applies if you cannot use `msgrv2` because of an older kernel.
  - Ceph `msgrv2` is required by default and requires kernel `5.11`. The `CephCluster` setting `network.connections.requireMsgr2: false`, or the same value under `cephClusterSpec` in Helm values, disables the protocol.
- **[breaking]** Automatic `.nfs` pool creation
  - Applies if you are creating a new NFS install.
  - New NFS installs must define a `CephBlockPool` for the `.nfs` pool because Rook no longer creates it automatically. A sample specification is available in `deploy/examples/nfs.yaml`; upgraded clusters are not affected.
- **[breaking]** Default CSI driver image configuration
  - Applies if you use custom CSI images.
  - Rook no longer sets default CSI driver container images. The `rook-csi-operator-image-set-configmap` now has empty values so the ceph-csi-operator uses its built-in defaults; custom image overrides must remain present in the configmap after an upgrade.

## Other recorded changes
- 6 (added 6)

[Full analysis](https://ratatosk.io/en/releases/rook/v1.21.0)

[Original release notes](https://github.com/rook/rook/releases/tag/v1.21.0)