CSI automatic migration

CSI automatic migration

OKD provides automatic migration for supported in-tree volume plug-ins to their equivalent Container Storage Interface (CSI) drivers.

CSI automatic migration is a Technology Preview feature only. Technology Preview features are not supported with Red Hat production service level agreements (SLAs) and might not be functionally complete. Red Hat does not recommend using them in production. These features provide early access to upcoming product features, enabling customers to test functionality and provide feedback during the development process.

For more information about the support scope of Red Hat Technology Preview features, see https://access.redhat.com/support/offerings/techpreview/.

Overview

With the automatic migration feature enabled, volumes provisioned using in-tree storage plug-ins supported by this feature are migrated to their counterpart CSI drivers.

The following drivers are supported:

Amazon Web Services (AWS) Elastic Block Storage (EBS)
OpenStack Cinder

CSI automatic migration should be seamless. Enabling this feature does not change how you use all existing API objects (for example, PersistentVolumes, PersistentVolumeClaims, and StorageClasses).

By default, automatic migration is disabled.

CSI automatic migration will be enabled by default in a future OKD release, so it is highly recommended that you test it now and report any issues.

Enabling CSI automatic migration

Enabling CSI automatic migration drains, and then restarts, all nodes in the cluster in sequence. This might take some time.

Procedure

Enable feature gates (see Nodes → Enabling features using feature gates).

After turning on Technology Preview features using feature gates, they cannot be turned off. As a result, cluster upgrades are prevented.

The following configuration example enables CSI automatic migration to both CSI drivers (AWS EBS and Cinder):
```
apiVersion: config.openshift.io/v1
kind: FeatureGate
metadata:
  name: cluster
spec:
  featureSet: TechPreviewNoUpgrade (1)
...
```
1 Enables automatic migration for AWS EBS and Cinder.

You can specify CSI automatic migration for a selected CSI driver by setting CustomNoUpgrade featureSet and for featuregates either:
- CSIMigrationAWS
- CSIMigrationOpenStack
The following configuration example enables automatic migration to the AWS EBS CSI driver only:
```
apiVersion: config.openshift.io/v1
kind: FeatureGate
metadata:
  name: cluster
spec:
  featureSet: CustomNoUpgrade
  customNoUpgrade:
    enabled:
      - CSIMigrationAWS (1)
    ...
```
1 Enables automatic migration for AWS EBS only.

Additional Resources

Enabling features using feature gates