Chapter 4. Using Container Storage Interface (CSI)

4.1. Configuring CSI volumes

The Container Storage Interface (CSI) allows OpenShift Container Platform to consume storage from storage back ends that implement the CSI interface as persistent storage.

4.1.1. CSI Architecture

CSI drivers are typically shipped as container images. These containers are not aware of OpenShift Container Platform where they run. To use CSI-compatible storage back end in OpenShift Container Platform, the cluster administrator must deploy several components that serve as a bridge between OpenShift Container Platform and the storage driver.

The following diagram provides a high-level overview about the components running in pods in the OpenShift Container Platform cluster.

Architecture of CSI components

It is possible to run multiple CSI drivers for different storage back ends. Each driver needs its own external controllers deployment and daemon set with the driver and CSI registrar.

4.1.1.1. External CSI controllers

External CSI Controllers is a deployment that deploys one or more pods with three containers:

  • An external CSI attacher container translates attach and detach calls from OpenShift Container Platform to respective ControllerPublish and ControllerUnpublish calls to the CSI driver.
  • An external CSI provisioner container that translates provision and delete calls from OpenShift Container Platform to respective CreateVolume and DeleteVolume calls to the CSI driver.
  • A CSI driver container

The CSI attacher and CSI provisioner containers communicate with the CSI driver container using UNIX Domain Sockets, ensuring that no CSI communication leaves the pod. The CSI driver is not accessible from outside of the pod.

Note

attach, detach, provision, and delete operations typically require the CSI driver to use credentials to the storage backend. Run the CSI controller pods on infrastructure nodes so the credentials are never leaked to user processes, even in the event of a catastrophic security breach on a compute node.

Note

The external attacher must also run for CSI drivers that do not support third-party attach or detach operations. The external attacher will not issue any ControllerPublish or ControllerUnpublish operations to the CSI driver. However, it still must run to implement the necessary OpenShift Container Platform attachment API.

4.1.1.2. CSI driver daemon set

The CSI driver daemon set runs a pod on every node that allows OpenShift Container Platform to mount storage provided by the CSI driver to the node and use it in user workloads (pods) as persistent volumes (PVs). The pod with the CSI driver installed contains the following containers:

  • A CSI driver registrar, which registers the CSI driver into the openshift-node service running on the node. The openshift-node process running on the node then directly connects with the CSI driver using the UNIX Domain Socket available on the node.
  • A CSI driver.

The CSI driver deployed on the node should have as few credentials to the storage back end as possible. OpenShift Container Platform will only use the node plug-in set of CSI calls such as NodePublish/NodeUnpublish and NodeStage/NodeUnstage, if these calls are implemented.

4.1.2. CSI drivers supported by OpenShift Container Platform

OpenShift Container Platform installs certain CSI drivers by default, giving users storage options that are not possible with in-tree volume plug-ins.

To create CSI-provisioned persistent volumes that mount to these supported storage assets, OpenShift Container Platform installs the necessary CSI driver Operator, the CSI driver, and the required storage class by default. For more details about the default namespace of the Operator and driver, see the documentation for the specific CSI Driver Operator.

The following table describes the CSI drivers that are installed with OpenShift Container Platform and which CSI features they support, such as volume snapshots, cloning, and resize.

Table 4.1. Supported CSI drivers and features in OpenShift Container Platform

CSI driverCSI volume snapshotsCSI cloningCSI resize

AWS EBS (Tech Preview)

 ✅

 -

 ✅

Google Cloud Platform (GCP) persistent disk (PD) (Tech Preview)

 ✅

 -

 ✅

Microsoft Azure Disk (Tech Preview)

 ✅

 ✅

 ✅

OpenStack Cinder

 ✅

 ✅

 ✅

OpenShift Container Storage

 ✅

 ✅

 ✅

OpenStack Manila

 ✅

 ✅

 ✅

Red Hat Virtualization (oVirt)

 -

 -

 -

VMware vSphere (Tech Preview)

 -

 -

 -

Important

If your CSI driver is not listed in the preceding table, you must follow the installation instructions provided by your CSI storage vendor to use their supported CSI features.

4.1.3. Dynamic provisioning

Dynamic provisioning of persistent storage depends on the capabilities of the CSI driver and underlying storage back end. The provider of the CSI driver should document how to create a storage class in OpenShift Container Platform and the parameters available for configuration.

The created storage class can be configured to enable dynamic provisioning.

Procedure

  • Create a default storage class that ensures all PVCs that do not require any special storage class are provisioned by the installed CSI driver.

    # oc create -f - << EOF
    apiVersion: storage.k8s.io/v1
    kind: StorageClass
    metadata:
      name: <storage-class> 1
      annotations:
        storageclass.kubernetes.io/is-default-class: "true"
    provisioner: <provisioner-name> 2
    parameters:
    EOF
    1
    The name of the storage class that will be created.
    2
    The name of the CSI driver that has been installed

4.1.4. Example using the CSI driver

The following example installs a default MySQL template without any changes to the template.

Prerequisites

  • The CSI driver has been deployed.
  • A storage class has been created for dynamic provisioning.

Procedure

  • Create the MySQL template:

    # oc new-app mysql-persistent

    Example output

    --> Deploying template "openshift/mysql-persistent" to project default
    ...

    # oc get pvc

    Example output

    NAME              STATUS    VOLUME                                   CAPACITY
    ACCESS MODES   STORAGECLASS   AGE
    mysql             Bound     kubernetes-dynamic-pv-3271ffcb4e1811e8   1Gi
    RWO            cinder         3s

4.2. CSI inline ephemeral volumes

Container Storage Interface (CSI) inline ephemeral volumes allow you to define a Pod spec that creates inline ephemeral volumes when a pod is deployed and delete them when a pod is destroyed.

This feature is only available with supported Container Storage Interface (CSI) drivers.

Important

CSI inline ephemeral volumes 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/.

4.2.1. Overview of CSI inline ephemeral volumes

Traditionally, volumes that are backed by Container Storage Interface (CSI) drivers can only be used with a PersistentVolume and PersistentVolumeClaim object combination.

This feature allows you to specify CSI volumes directly in the Pod specification, rather than in a PersistentVolume object. Inline volumes are ephemeral and do not persist across pod restarts.

4.2.1.1. Support limitations

By default, OpenShift Container Platform supports CSI inline ephemeral volumes with these limitations:

  • Support is only available for CSI drivers. In-tree and FlexVolumes are not supported.
  • OpenShift Container Platform does not include any CSI drivers. Use the CSI drivers provided by community or storage vendors. Follow the installation instructions provided by the CSI driver.
  • CSI drivers might not have implemented the inline volume functionality, including Ephemeral capacity. For details, see the CSI driver documentation.

4.2.2. Embedding a CSI inline ephemeral volume in the Pod specification

You can embed a CSI inline ephemeral volume in the Pod specification in OpenShift Container Platform. At runtime, nested inline volumes follow the ephemeral lifecycle of their associated pods so that the CSI driver handles all phases of volume operations as pods are created and destroyed.

Procedure

  1. Create the Pod object definition and save it to a file.
  2. Embed the CSI inline ephemeral volume in the file.

    my-csi-app.yaml

    kind: Pod
    apiVersion: v1
    metadata:
      name: my-csi-app
    spec:
      containers:
        - name: my-frontend
          image: busybox
          volumeMounts:
          - mountPath: "/data"
            name: my-csi-inline-vol
          command: [ "sleep", "1000000" ]
      volumes: 1
        - name: my-csi-inline-vol
          csi:
            driver: inline.storage.kubernetes.io
            volumeAttributes:
              foo: bar

    1
    The name of the volume that is used by pods.
  3. Create the object definition file that you saved in the previous step.

    $ oc create -f my-csi-app.yaml

4.3. CSI volume snapshots

This document describes how to use volume snapshots with supported Container Storage Interface (CSI) drivers to help protect against data loss in OpenShift Container Platform. Familiarity with persistent volumes is suggested.

4.3.1. Overview of CSI volume snapshots

A snapshot represents the state of the storage volume in a cluster at a particular point in time. Volume snapshots can be used to provision a new volume.

OpenShift Container Platform supports CSI volume snapshots by default. However, a specific CSI driver is required.

With CSI volume snapshots, a cluster administrator can:

  • Deploy a third-party CSI driver that supports snapshots.
  • Create a new persistent volume claim (PVC) from an existing volume snapshot.
  • Take a snapshot of an existing PVC.
  • Restore a snapshot as a different PVC.
  • Delete an existing volume snapshot.

With CSI volume snapshots, an app developer can:

  • Use volume snapshots as building blocks for developing application- or cluster-level storage backup solutions.
  • Rapidly rollback to a previous development version.
  • Use storage more efficiently by not having to make a full copy each time.

Be aware of the following when using volume snapshots:

  • Support is only available for CSI drivers. In-tree and FlexVolumes are not supported.
  • OpenShift Container Platform only ships with select CSI drivers. For CSI drivers that are not provided by an OpenShift Container Platform Driver Operator, it is recommended to use the CSI drivers provided by community or storage vendors. Follow the installation instructions provided by the CSI driver.
  • CSI drivers may or may not have implemented the volume snapshot functionality. CSI drivers that have provided support for volume snapshots will likely use the csi-external-snapshotter sidecar. See documentation provided by the CSI driver for details.
  • OpenShift Container Platform 4.8 supports version 1.1.0 of the CSI specification.

4.3.2. CSI snapshot controller and sidecar

OpenShift Container Platform provides a snapshot controller that is deployed into the control plane. In addition, your CSI driver vendor provides the CSI snapshot sidecar as a helper container that is installed during the CSI driver installation.

The CSI snapshot controller and sidecar provide volume snapshotting through the OpenShift Container Platform API. These external components run in the cluster.

The external controller is deployed by the CSI Snapshot Controller Operator.

4.3.2.1. External controller

The CSI snapshot controller binds VolumeSnapshot and VolumeSnapshotContent objects. The controller manages dynamic provisioning by creating and deleting VolumeSnapshotContent objects.

4.3.2.2. External sidecar

Your CSI driver vendor provides the csi-external-snapshotter sidecar. This is a separate helper container that is deployed with the CSI driver. The sidecar manages snapshots by triggering CreateSnapshot and DeleteSnapshot operations. Follow the installation instructions provided by your vendor.

4.3.3. About the CSI Snapshot Controller Operator

The CSI Snapshot Controller Operator runs in the openshift-cluster-storage-operator namespace. It is installed by the Cluster Version Operator (CVO) in all clusters by default.

The CSI Snapshot Controller Operator installs the CSI snapshot controller, which runs in the openshift-cluster-storage-operator namespace.

4.3.3.1. Volume snapshot CRDs

During OpenShift Container Platform installation, the CSI Snapshot Controller Operator creates the following snapshot custom resource definitions (CRDs) in the snapshot.storage.k8s.io/v1 API group:

VolumeSnapshotContent

A snapshot taken of a volume in the cluster that has been provisioned by a cluster administrator.

Similar to the PersistentVolume object, the VolumeSnapshotContent CRD is a cluster resource that points to a real snapshot in the storage back end.

For manually pre-provisioned snapshots, a cluster administrator creates a number of VolumeSnapshotContent CRDs. These carry the details of the real volume snapshot in the storage system.

The VolumeSnapshotContent CRD is not namespaced and is for use by a cluster administrator.

VolumeSnapshot

Similar to the PersistentVolumeClaim object, the VolumeSnapshot CRD defines a developer request for a snapshot. The CSI Snapshot Controller Operator runs the CSI snapshot controller, which handles the binding of a VolumeSnapshot CRD with an appropriate VolumeSnapshotContent CRD. The binding is a one-to-one mapping.

The VolumeSnapshot CRD is namespaced. A developer uses the CRD as a distinct request for a snapshot.

VolumeSnapshotClass

Allows a cluster administrator to specify different attributes belonging to a VolumeSnapshot object. These attributes may differ among snapshots taken of the same volume on the storage system, in which case they would not be expressed by using the same storage class of a persistent volume claim.

The VolumeSnapshotClass CRD defines the parameters for the csi-external-snapshotter sidecar to use when creating a snapshot. This allows the storage back end to know what kind of snapshot to dynamically create if multiple options are supported.

Dynamically provisioned snapshots use the VolumeSnapshotClass CRD to specify storage-provider-specific parameters to use when creating a snapshot.

The VolumeSnapshotContentClass CRD is not namespaced and is for use by a cluster administrator to enable global configuration options for their storage back end.

4.3.4. Volume snapshot provisioning

There are two ways to provision snapshots: dynamically and manually.

4.3.4.1. Dynamic provisioning

Instead of using a preexisting snapshot, you can request that a snapshot be taken dynamically from a persistent volume claim. Parameters are specified using a VolumeSnapshotClass CRD.

4.3.4.2. Manual provisioning

As a cluster administrator, you can manually pre-provision a number of VolumeSnapshotContent objects. These carry the real volume snapshot details available to cluster users.

4.3.5. Creating a volume snapshot

When you create a VolumeSnapshot object, OpenShift Container Platform creates a volume snapshot.

Prerequisites

  • Logged in to a running OpenShift Container Platform cluster.
  • A PVC created using a CSI driver that supports VolumeSnapshot objects.
  • A storage class to provision the storage back end.
  • No pods are using the persistent volume claim (PVC) that you want to take a snapshot of.

    Note

    Do not create a volume snapshot of a PVC if a pod is using it. Doing so might cause data corruption because the PVC is not quiesced (paused). Be sure to first tear down a running pod to ensure consistent snapshots.

Procedure

To dynamically create a volume snapshot:

  1. Create a file with the VolumeSnapshotClass object described by the following YAML:

    volumesnapshotclass.yaml

    apiVersion: snapshot.storage.k8s.io/v1
    kind: VolumeSnapshotClass
    metadata:
      name: csi-hostpath-snap
    driver: hostpath.csi.k8s.io 1
    deletionPolicy: Delete

    1
    The name of the CSI driver that is used to create snapshots of this VolumeSnapshotClass object. The name must be the same as the Provisioner field of the storage class that is responsible for the PVC that is being snapshotted.
  2. Create the object you saved in the previous step by entering the following command:

    $ oc create -f volumesnapshotclass.yaml
  3. Create a VolumeSnapshot object:

    volumesnapshot-dynamic.yaml

    apiVersion: snapshot.storage.k8s.io/v1
    kind: VolumeSnapshot
    metadata:
      name: mysnap
    spec:
      volumeSnapshotClassName: csi-hostpath-snap 1
      source:
        persistentVolumeClaimName: myclaim 2

    1
    The request for a particular class by the volume snapshot. If the volumeSnapshotClassName setting is absent and there is a default volume snapshot class, a snapshot is created with the default volume snapshot class name. But if the field is absent and no default volume snapshot class exists, then no snapshot is created.
    2
    The name of the PersistentVolumeClaim object bound to a persistent volume. This defines what you want to create a snapshot of. Required for dynamically provisioning a snapshot.
  4. Create the object you saved in the previous step by entering the following command:

    $ oc create -f volumesnapshot-dynamic.yaml

To manually provision a snapshot:

  1. Provide a value for the volumeSnapshotContentName parameter as the source for the snapshot, in addition to defining volume snapshot class as shown above.

    volumesnapshot-manual.yaml

    apiVersion: snapshot.storage.k8s.io/v1
    kind: VolumeSnapshot
    metadata:
      name: snapshot-demo
    spec:
      source:
        volumeSnapshotContentName: mycontent 1

    1
    The volumeSnapshotContentName parameter is required for pre-provisioned snapshots.
  2. Create the object you saved in the previous step by entering the following command:

    $ oc create -f volumesnapshot-manual.yaml

Verification

After the snapshot has been created in the cluster, additional details about the snapshot are available.

  1. To display details about the volume snapshot that was created, enter the following command:

    $ oc describe volumesnapshot mysnap

    The following example displays details about the mysnap volume snapshot:

    volumesnapshot.yaml

    apiVersion: snapshot.storage.k8s.io/v1
    kind: VolumeSnapshot
    metadata:
      name: mysnap
    spec:
      source:
        persistentVolumeClaimName: myclaim
      volumeSnapshotClassName: csi-hostpath-snap
    status:
      boundVolumeSnapshotContentName: snapcontent-1af4989e-a365-4286-96f8-d5dcd65d78d6 1
      creationTime: "2020-01-29T12:24:30Z" 2
      readyToUse: true 3
      restoreSize: 500Mi

    1
    The pointer to the actual storage content that was created by the controller.
    2
    The time when the snapshot was created. The snapshot contains the volume content that was available at this indicated time.
    3
    If the value is set to true, the snapshot can be used to restore as a new PVC.
    If the value is set to false, the snapshot was created. However, the storage back end needs to perform additional tasks to make the snapshot usable so that it can be restored as a new volume. For example, Amazon Elastic Block Store data might be moved to a different, less expensive location, which can take several minutes.
  2. To verify that the volume snapshot was created, enter the following command:

    $ oc get volumesnapshotcontent

    The pointer to the actual content is displayed. If the boundVolumeSnapshotContentName field is populated, a VolumeSnapshotContent object exists and the snapshot was created.

  3. To verify that the snapshot is ready, confirm that the VolumeSnapshot object has readyToUse: true.

4.3.6. Deleting a volume snapshot

You can configure how OpenShift Container Platform deletes volume snapshots.

Procedure

  1. Specify the deletion policy that you require in the VolumeSnapshotClass object, as shown in the following example:

    volumesnapshotclass.yaml

    apiVersion: snapshot.storage.k8s.io/v1
    kind: VolumeSnapshotClass
    metadata:
      name: csi-hostpath-snap
    driver: hostpath.csi.k8s.io
    deletionPolicy: Delete 1

    1
    When deleting the volume snapshot, if the Delete value is set, the underlying snapshot is deleted along with the VolumeSnapshotContent object. If the Retain value is set, both the underlying snapshot and VolumeSnapshotContent object remain.
    If the Retain value is set and the VolumeSnapshot object is deleted without deleting the corresponding VolumeSnapshotContent object, the content remains. The snapshot itself is also retained in the storage back end.
  2. Delete the volume snapshot by entering the following command:

    $ oc delete volumesnapshot <volumesnapshot_name>

    Example output

    volumesnapshot.snapshot.storage.k8s.io "mysnapshot" deleted

  3. If the deletion policy is set to Retain, delete the volume snapshot content by entering the following command:

    $ oc delete volumesnapshotcontent <volumesnapshotcontent_name>
  4. Optional: If the VolumeSnapshot object is not successfully deleted, enter the following command to remove any finalizers for the leftover resource so that the delete operation can continue:

    Important

    Only remove the finalizers if you are confident that there are no existing references from either persistent volume claims or volume snapshot contents to the VolumeSnapshot object. Even with the --force option, the delete operation does not delete snapshot objects until all finalizers are removed.

    $ oc patch -n $PROJECT volumesnapshot/$NAME --type=merge -p '{"metadata": {"finalizers":null}}'

    Example output

    volumesnapshotclass.snapshot.storage.k8s.io "csi-ocs-rbd-snapclass" deleted

    The finalizers are removed and the volume snapshot is deleted.

4.3.7. Restoring a volume snapshot

The VolumeSnapshot CRD content can be used to restore the existing volume to a previous state.

After your VolumeSnapshot CRD is bound and the readyToUse value is set to true, you can use that resource to provision a new volume that is pre-populated with data from the snapshot. .Prerequisites * Logged in to a running OpenShift Container Platform cluster. * A persistent volume claim (PVC) created using a Container Storage Interface (CSI) driver that supports volume snapshots. * A storage class to provision the storage back end. * A volume snapshot has been created and is ready to use.

Procedure

  1. Specify a VolumeSnapshot data source on a PVC as shown in the following:

    pvc-restore.yaml

    apiVersion: v1
    kind: PersistentVolumeClaim
    metadata:
      name: myclaim-restore
    spec:
      storageClassName: csi-hostpath-sc
      dataSource:
        name: mysnap 1
        kind: VolumeSnapshot 2
        apiGroup: snapshot.storage.k8s.io 3
      accessModes:
        - ReadWriteOnce
      resources:
        requests:
          storage: 1Gi

    1
    Name of the VolumeSnapshot object representing the snapshot to use as source.
    2
    Must be set to the VolumeSnapshot value.
    3
    Must be set to the snapshot.storage.k8s.io value.
  2. Create a PVC by entering the following command:

    $ oc create -f pvc-restore.yaml
  3. Verify that the restored PVC has been created by entering the following command:

    $ oc get pvc

    A new PVC such as myclaim-restore is displayed.

4.4. CSI volume cloning

Volume cloning duplicates an existing persistent volume to help protect against data loss in OpenShift Container Platform. This feature is only available with supported Container Storage Interface (CSI) drivers. You should be familiar with persistent volumes before you provision a CSI volume clone.

4.4.1. Overview of CSI volume cloning

A Container Storage Interface (CSI) volume clone is a duplicate of an existing persistent volume at a particular point in time.

Volume cloning is similar to volume snapshots, although it is more efficient. For example, a cluster administrator can duplicate a cluster volume by creating another instance of the existing cluster volume.

Cloning creates an exact duplicate of the specified volume on the back-end device, rather than creating a new empty volume. After dynamic provisioning, you can use a volume clone just as you would use any standard volume.

No new API objects are required for cloning. The existing dataSource field in the PersistentVolumeClaim object is expanded so that it can accept the name of an existing PersistentVolumeClaim in the same namespace.

4.4.1.1. Support limitations

By default, OpenShift Container Platform supports CSI volume cloning with these limitations:

  • The destination persistent volume claim (PVC) must exist in the same namespace as the source PVC.
  • The source and destination storage class must be the same.
  • Support is only available for CSI drivers. In-tree and FlexVolumes are not supported.
  • OpenShift Container Platform does not include any CSI drivers. Use the CSI drivers provided by community or storage vendors. Follow the installation instructions provided by the CSI driver.
  • CSI drivers might not have implemented the volume cloning functionality. For details, see the CSI driver documentation.
  • OpenShift Container Platform 4.8 supports version 1.1.0 of the CSI specification.

4.4.2. Provisioning a CSI volume clone

When you create a cloned persistent volume claim (PVC) API object, you trigger the provisioning of a CSI volume clone. The clone pre-populates with the contents of another PVC, adhering to the same rules as any other persistent volume. The one exception is that you must add a dataSource that references an existing PVC in the same namespace.

Prerequisites

  • You are logged in to a running OpenShift Container Platform cluster.
  • Your PVC is created using a CSI driver that supports volume cloning.
  • Your storage back end is configured for dynamic provisioning. Cloning support is not available for static provisioners.

Procedure

To clone a PVC from an existing PVC:

  1. Create and save a file with the PersistentVolumeClaim object described by the following YAML:

    pvc-clone.yaml

    apiVersion: v1
    kind: PersistentVolumeClaim
    metadata:
      name: pvc-1-clone
      namespace: mynamespace
    spec:
      storageClassName: csi-cloning 1
      accessModes:
        - ReadWriteOnce
      resources:
        requests:
          storage: 5Gi
      dataSource:
        kind: PersistentVolumeClaim
        name: pvc-1

    1
    The name of the storage class that provisions the storage back end. The default storage class can be used and storageClassName can be omitted in the spec.
  2. Create the object you saved in the previous step by running the following command:

    $ oc create -f pvc-clone.yaml

    A new PVC pvc-1-clone is created.

  3. Verify that the volume clone was created and is ready by running the following command:

    $ oc get pvc pvc-1-clone

    The pvc-1-clone shows that it is Bound.

    You are now ready to use the newly cloned PVC to configure a pod.

  4. Create and save a file with the Pod object described by the YAML. For example:

    kind: Pod
    apiVersion: v1
    metadata:
      name: mypod
    spec:
      containers:
        - name: myfrontend
          image: dockerfile/nginx
          volumeMounts:
          - mountPath: "/var/www/html"
            name: mypd
      volumes:
        - name: mypd
          persistentVolumeClaim:
            claimName: pvc-1-clone 1
    1
    The cloned PVC created during the CSI volume cloning operation.

    The created Pod object is now ready to consume, clone, snapshot, or delete your cloned PVC independently of its original dataSource PVC.

4.5. CSI automatic migration

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

Important

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/.

4.5.1. 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.

Important

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

4.5.2. Enabling CSI automatic migration

Note

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).

    Important

    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.

4.5.3. Additional Resources

4.6. AWS Elastic Block Store CSI Driver Operator

4.6.1. Overview

OpenShift Container Platform is capable of provisioning persistent volumes (PVs) using the Container Storage Interface (CSI) driver for AWS Elastic Block Store (EBS).

Important

AWS EBS CSI Driver Operator 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/.

Familiarity with persistent storage and configuring CSI volumes is recommended when working with a Container Storage Interface (CSI) Operator and driver.

To create CSI-provisioned PVs that mount to AWS EBS storage assets, OpenShift Container Platform installs the AWS EBS CSI Driver Operator and the AWS EBS CSI driver by default in the openshift-cluster-csi-drivers namespace.

  • The AWS EBS CSI Driver Operator provides a StorageClass by default that you can use to create PVCs. You also have the option to create the AWS EBS StorageClass as described in Persistent storage using AWS Elastic Block Store.
  • The AWS EBS CSI driver enables you to create and mount AWS EBS PVs.
Note

If you installed the AWS EBS CSI Operator and driver on a OpenShift Container Platform 4.5 cluster, you must uninstall the 4.5 Operator and driver before you update to OpenShift Container Platform 4.8.

4.6.2. About CSI

Storage vendors have traditionally provided storage drivers as part of Kubernetes. With the implementation of the Container Storage Interface (CSI), third-party providers can instead deliver storage plug-ins using a standard interface without ever having to change the core Kubernetes code.

CSI Operators give OpenShift Container Platform users storage options, such as volume snapshots, that are not possible with in-tree volume plug-ins.

Important

OpenShift Container Platform defaults to using an in-tree (non-CSI) plug-in to provision AWS EBS storage.

In future OpenShift Container Platform versions, volumes provisioned using existing in-tree plug-ins are planned for migration to their equivalent CSI driver. CSI automatic migration should be seamless. Migration does not change how you use all existing API objects, such as persistent volumes, persistent volume claims, and storage classes. For more information about migration, see CSI automatic migration.

After full migration, in-tree plug-ins will eventually be removed in future versions of OpenShift Container Platform.

For information about dynamically provisioning AWS EBS persistent volumes in OpenShift Container Platform, see Persistent storage using AWS Elastic Block Store.

4.7. Azure Disk CSI Driver Operator

4.7.1. Overview

OpenShift Container Platform is capable of provisioning persistent volumes (PVs) using the Container Storage Interface (CSI) driver for Microsoft Azure Disk Storage.

Important

Azure Disk CSI Driver Operator 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/.

Familiarity with persistent storage and configuring CSI volumes is recommended when working with a CSI Operator and driver.

To create CSI-provisioned PVs that mount to Azure Disk storage assets with this feature is enabled, OpenShift Container Platform installs the Azure Disk CSI Driver Operator and the Azure Disk CSI driver by default in the openshift-cluster-csi-drivers namespace.

  • The Azure Disk CSI Driver Operator, after being enabled, provides a storage class named managed-csi that you can use to create persistent volume claims (PVCs). The Azure Disk CSI Driver Operator supports dynamic volume provisioning by allowing storage volumes to be created on-demand, eliminating the need for cluster administrators to pre-provision storage.
  • The Azure Disk CSI driver enables you to create and mount Azure Disk PVs.

4.7.2. About CSI

Storage vendors have traditionally provided storage drivers as part of Kubernetes. With the implementation of the Container Storage Interface (CSI), third-party providers can instead deliver storage plug-ins using a standard interface without ever having to change the core Kubernetes code.

CSI Operators give OpenShift Container Platform users storage options, such as volume snapshots, that are not possible with in-tree volume plug-ins.

Important

OpenShift Container Platform defaults to using an in-tree (non-CSI) plug-in to provision Azure Disk storage.

In future OpenShift Container Platform versions, volumes provisioned using existing in-tree plug-ins are planned for migration to their equivalent CSI driver. CSI automatic migration should be seamless. Migration does not change how you use all existing API objects, such as persistent volumes, persistent volume claims, and storage classes. For more information about migration, see CSI automatic migration.

After full migration, in-tree plug-ins will eventually be removed in later versions of OpenShift Container Platform.

4.7.3. Enabling the Azure CSI Driver Operator

To enable the Azure Container Storage Interface (CSI) Driver Operator, you must enable feature gates with the TechPreviewNoUpgrade feature set.

Procedure

  1. Enable feature gates with the TechPreviewNoUpgrade feature set (see NodesEnabling features using feature gates).

    Important

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

  2. Verify the cluster operator storage:

    $ oc get co storage
    NAME    VERSION                             AVAILABLE   PROGRESSING DEGRADED    SINCE
    storage 4.8.0-0.nightly-2021-04-30-201824   True        False       False       4h26m
    • AVAILABLE should be "True".
    • PROGRESSING should be "False".
    • DEGRADED should be "False".
  3. Verify the status of the pods in the openshift-cluster-csi-drivers namespace to ensure that they are running:

    $ oc get pod -n openshift-cluster-csi-drivers
    NAME                                                    READY   STATUS  RESTARTS    AGE
    azure-disk-csi-driver-controller-5949bf45fd-pm4qb       11/11   Running 0           39m
    azure-disk-csi-driver-node-2tcxr                        3/3     Running 0           53m
    azure-disk-csi-driver-node-2xjzm                        3/3     Running 0           53m
    azure-disk-csi-driver-node-6wrgk                        3/3     Running 0           53m
    azure-disk-csi-driver-node-frvx2                        3/3     Running 0           53m
    azure-disk-csi-driver-node-lf5kb                        3/3     Running 0           53m
    azure-disk-csi-driver-node-mqdhh                        3/3     Running 0           53m
    azure-disk-csi-driver-operator-7d966fc6c5-x74x5         1/1     Running 0           44m
  4. Verify that the storage class is installed:

    $ oc get storageclass
    NAME                        PROVISIONER                     RECLAIMPOLICY   VOLUMEBINDINGMODE       ALLOWVOLUMEEXPANSION    AGE
    managed-premium (default)   kubernetes.io/azure-disk        Delete          WaitForFirstConsumer    true                    76m
    managed-csi                 disk.csi.azure.com              Delete          WaitForFirstConsumer    true                    51m 1
    1
    Azure storage class

4.8. GCP PD CSI Driver Operator

4.8.1. Overview

OpenShift Container Platform can provision persistent volumes (PVs) using the Container Storage Interface (CSI) driver for Google Cloud Platform (GCP) persistent disk (PD) storage.

Familiarity with persistent storage and configuring CSI volumes is recommended when working with a Container Storage Interface (CSI) Operator and driver.

To create CSI-provisioned persistent volumes (PVs) that mount to GCP PD storage assets, OpenShift Container Platform installs the GCP PD CSI Driver Operator and the GCP PD CSI driver by default in the openshift-cluster-csi-drivers namespace.

  • GCP PD CSI Driver Operator: By default, the Operator provides a storage class that you can use to create PVCs. You also have the option to create the GCP PD storage class as described in Persistent storage using GCE Persistent Disk.
  • GCP PD driver: The driver enables you to create and mount GCP PD PVs.
Important

OpenShift Container Platform defaults to using an in-tree (non-CSI) plug-in to provision GCP PD storage.

In future OpenShift Container Platform versions, volumes provisioned using existing in-tree plug-ins are planned for migration to their equivalent CSI driver. CSI automatic migration should be seamless. Migration does not change how you use all existing API objects, such as persistent volumes, persistent volume claims, and storage classes. For more information about migration, see CSI automatic migration.

After full migration, in-tree plug-ins will eventually be removed in future versions of OpenShift Container Platform.

4.8.2. About CSI

Storage vendors have traditionally provided storage drivers as part of Kubernetes. With the implementation of the Container Storage Interface (CSI), third-party providers can instead deliver storage plug-ins using a standard interface without ever having to change the core Kubernetes code.

CSI Operators give OpenShift Container Platform users storage options, such as volume snapshots, that are not possible with in-tree volume plug-ins.

4.8.3. GCP PD CSI driver storage class parameters

The Google Cloud Platform (GCP) persistent disk (PD) Container Storage Interface (CSI) driver uses the CSI external-provisioner sidecar as a controller. This is a separate helper container that is deployed with the CSI driver. The sidecar manages persistent volumes (PVs) by triggering the CreateVolume operation.

The GCP PD CSI driver uses the csi.storage.k8s.io/fstype parameter key to support dynamic provisioning. The following table describes all the GCP PD CSI storage class parameters that are supported by OpenShift Container Platform.

Table 4.2. CreateVolume Parameters

ParameterValuesDefaultDescription

type

pd-ssd or pd-standard

pd-standard

Allows you to choose between standard PVs or solid-state-drive PVs.

replication-type

none or regional-pd

none

Allows you to choose between zonal or regional PVs.

disk-encryption-kms-key

Fully qualified resource identifier for the key to use to encrypt new disks.

Empty string

Uses customer-managed encryption keys (CMEK) to encrypt new disks.

4.8.4. Creating a custom-encrypted persistent volume

When you create a PersistentVolumeClaim object, OpenShift Container Platform provisions a new persistent volume (PV) and creates a PersistentVolume object. You can add a custom encryption key in Google Cloud Platform (GCP) to protect a PV in your cluster by encrypting the newly created PV.

For encryption, the newly attached PV that you create uses customer-managed encryption keys (CMEK) on a cluster by using a new or existing Google Cloud Key Management Service (KMS) key.

Prerequisites

  • You are logged in to a running OpenShift Container Platform cluster.
  • You have created a Cloud KMS key ring and key version.

For more information about CMEK and Cloud KMS resources, see Using customer-managed encryption keys (CMEK).

Procedure

To create a custom-encrypted PV, complete the following steps:

  1. Create a storage class with the Cloud KMS key. The following example enables dynamic provisioning of encrypted volumes:

    apiVersion: storage.k8s.io/v1
    kind: StorageClass
    metadata:
      name: csi-gce-pd-cmek
    provisioner: pd.csi.storage.gke.io
    volumeBindingMode: "WaitForFirstConsumer"
    allowVolumeExpansion: true
    parameters:
      type: pd-standard
      disk-encryption-kms-key: projects/<key-project-id>/locations/<location>/keyRings/<key-ring>/cryptoKeys/<key> 1
    1
    This field must be the resource identifier for the key that will be used to encrypt new disks. Values are case-sensitive. For more information about providing key ID values, see Retrieving a resource’s ID and Getting a Cloud KMS resource ID.
    Note

    You cannot add the disk-encryption-kms-key parameter to an existing storage class. However, you can delete the storage class and recreate it with the same name and a different set of parameters. If you do this, the provisioner of the existing class must be pd.csi.storage.gke.io.

  2. Deploy the storage class on your OpenShift Container Platform cluster using the oc command:

    $ oc describe storageclass csi-gce-pd-cmek

    Example output

    Name:                  csi-gce-pd-cmek
    IsDefaultClass:        No
    Annotations:           None
    Provisioner:           pd.csi.storage.gke.io
    Parameters:            disk-encryption-kms-key=projects/key-project-id/locations/location/keyRings/ring-name/cryptoKeys/key-name,type=pd-standard
    AllowVolumeExpansion:  true
    MountOptions:          none
    ReclaimPolicy:         Delete
    VolumeBindingMode:     WaitForFirstConsumer
    Events:                none

  3. Create a file named pvc.yaml that matches the name of your storage class object that you created in the previous step:

    kind: PersistentVolumeClaim
    apiVersion: v1
    metadata:
      name: podpvc
    spec:
      accessModes:
        - ReadWriteOnce
      storageClassName: csi-gce-pd-cmek
      resources:
        requests:
          storage: 6Gi
    Note

    If you marked the new storage class as default, you can omit the storageClassName field.

  4. Apply the PVC on your cluster:

    $ oc apply -f pvc.yaml
  5. Get the status of your PVC and verify that it is created and bound to a newly provisioned PV:

    $ oc get pvc

    Example output

    NAME      STATUS    VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS     AGE
    podpvc    Bound     pvc-e36abf50-84f3-11e8-8538-42010a800002   10Gi       RWO            csi-gce-pd-cmek  9s

    Note

    If your storage class has the volumeBindingMode field set to WaitForFirstConsumer, you must create a pod to use the PVC before you can verify it.

Your CMEK-protected PV is now ready to use with your OpenShift Container Platform cluster.

4.9. OpenStack Cinder CSI Driver Operator

4.9.1. Overview

OpenShift Container Platform is capable of provisioning persistent volumes (PVs) using the Container Storage Interface (CSI) driver for OpenStack Cinder.

Familiarity with persistent storage and configuring CSI volumes is recommended when working with a Container Storage Interface (CSI) Operator and driver.

To create CSI-provisioned PVs that mount to OpenStack Cinder storage assets, OpenShift Container Platform installs the OpenStack Cinder CSI Driver Operator and the OpenStack Cinder CSI driver in the openshift-cluster-csi-drivers namespace.

  • The OpenStack Cinder CSI Driver Operator provides a CSI storage class that you can use to create PVCs.
  • The OpenStack Cinder CSI driver enables you to create and mount OpenStack Cinder PVs.

For OpenShift Container Platform, automatic migration from OpenStack Cinder in-tree to the CSI driver is available as a Technology Preview (TP) feature. With migration enabled, volumes provisioned using the existing in-tree plug-in are automatically migrated to use the OpenStack Cinder CSI driver. For more information, see CSI automatic migration feature.

4.9.2. About CSI

Storage vendors have traditionally provided storage drivers as part of Kubernetes. With the implementation of the Container Storage Interface (CSI), third-party providers can instead deliver storage plug-ins using a standard interface without ever having to change the core Kubernetes code.

CSI Operators give OpenShift Container Platform users storage options, such as volume snapshots, that are not possible with in-tree volume plug-ins.

Important

OpenShift Container Platform defaults to using an in-tree (non-CSI) plug-in to provision Cinder storage.

In future OpenShift Container Platform versions, volumes provisioned using existing in-tree plug-ins are planned for migration to their equivalent CSI driver. CSI automatic migration should be seamless. Migration does not change how you use all existing API objects, such as persistent volumes, persistent volume claims, and storage classes. For more information about migration, see CSI automatic migration.

After full migration, in-tree plug-ins will eventually be removed in future versions of OpenShift Container Platform.

4.9.3. Making OpenStack Cinder CSI the default storage class

The OpenStack Cinder CSI driver uses the cinder.csi.openstack.org parameter key to support dynamic provisioning.

To enable OpenStack Cinder CSI provisioning in OpenShift Container Platform, it is recommended that you overwrite the default in-tree storage class with standard-csi. Alternatively, you can create the persistent volume claim (PVC) and specify the storage class as "standard-csi".

In OpenShift Container Platform, the default storage class references the in-tree Cinder driver. However, with CSI automatic migration enabled, volumes created using the default storage class actually use the CSI driver.

Recommended procedure

Use the following steps to apply the standard-csi storage class by overwriting the default in-tree storage class.

  1. List the storage class:

    $ oc get storageclass

    Example output

    NAME                   PROVISIONER                RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
    standard(default)      cinder.csi.openstack.org   Delete          WaitForFirstConsumer   true                   46h
    standard-csi           kubernetes.io/cinder       Delete          WaitForFirstConsumer   true                   46h

  2. Change the value of the annotation storageclass.kubernetes.io/is-default-class to false for the default storage class, as shown in the following example:

    $ oc patch storageclass standard -p '{"metadata": {"annotations": {"storageclass.kubernetes.io/is-default-class": "false"}}}'
  3. Make another storage class the default by adding or modifying the annotation as storageclass.kubernetes.io/is-default-class=true.

    $ oc patch storageclass standard-csi -p '{"metadata": {"annotations": {"storageclass.kubernetes.io/is-default-class": "true"}}}'
  4. Verify that the PVC is now referencing the CSI storage class by default:

    $ oc get storageclass

    Example output

    NAME                   PROVISIONER                RECLAIMPOLICY   VOLUMEBINDINGMODE      ALLOWVOLUMEEXPANSION   AGE
    standard               kubernetes.io/cinder       Delete          WaitForFirstConsumer   true                   46h
    standard-csi(default)  cinder.csi.openstack.org   Delete          WaitForFirstConsumer   true                   46h

  5. Optional: You can define a new PVC without having to specify the storage class:

    apiVersion: v1
    kind: PersistentVolumeClaim
    metadata:
      name: cinder-claim
    spec:
      accessModes:
        - ReadWriteOnce
      resources:
        requests:
          storage: 1Gi

    A PVC that does not specify a specific storage class is automatically provisioned by using the default storage class.

  6. Optional: After the new file has been configured, create it in your cluster:

    $ oc create -f cinder-claim.yaml

Additional resources

4.10. OpenStack Manila CSI Driver Operator

4.10.1. Overview

OpenShift Container Platform is capable of provisioning persistent volumes (PVs) using the Container Storage Interface (CSI) driver for the OpenStack Manila shared file system service.

Familiarity with persistent storage and configuring CSI volumes is recommended when working with a Container Storage Interface (CSI) Operator and driver.

To create CSI-provisioned PVs that mount to Manila storage assets, OpenShift Container Platform installs the Manila CSI Driver Operator and the Manila CSI driver by default on any OpenStack cluster that has the Manila service enabled.

  • The Manila CSI Driver Operator creates the required storage class that is needed to create PVCs for all available Manila share types. The Operator is installed in the openshift-cluster-csi-drivers namespace.
  • The Manila CSI driver enables you to create and mount Manila PVs. The driver is installed in the openshift-manila-csi-driver namespace.

4.10.2. About CSI

Storage vendors have traditionally provided storage drivers as part of Kubernetes. With the implementation of the Container Storage Interface (CSI), third-party providers can instead deliver storage plug-ins using a standard interface without ever having to change the core Kubernetes code.

CSI Operators give OpenShift Container Platform users storage options, such as volume snapshots, that are not possible with in-tree volume plug-ins.

4.10.3. Dynamically provisioning Manila CSI volumes

OpenShift Container Platform installs a storage class for each available Manila share type.

The YAML files that are created are completely decoupled from Manila and from its Container Storage Interface (CSI) plug-in. As an application developer, you can dynamically provision ReadWriteMany (RWX) storage and deploy pods with applications that safely consume the storage using YAML manifests.

You can use the same pod and persistent volume claim (PVC) definitions on-premise that you use with OpenShift Container Platform on AWS, GCP, Azure, and other platforms, with the exception of the storage class reference in the PVC definition.

Note

Manila service is optional. If the service is not enabled in Red Hat OpenStack Platform (RHOSP), the Manila CSI driver is not installed and the storage classes for Manila are not created.

Prerequisites

  • RHOSP is deployed with appropriate Manila share infrastructure so that it can be used to dynamically provision and mount volumes in OpenShift Container Platform.

Procedure (UI)

To dynamically create a Manila CSI volume using the web console:

  1. In the OpenShift Container Platform console, click StoragePersistent Volume Claims.
  2. In the persistent volume claims overview, click Create Persistent Volume Claim.
  3. Define the required options on the resulting page.

    1. Select the appropriate storage class.
    2. Enter a unique name for the storage claim.
    3. Select the access mode to specify read and write access for the PVC you are creating.

      Important

      Use RWX if you want the persistent volume (PV) that fulfills this PVC to be mounted to multiple pods on multiple nodes in the cluster.

  4. Define the size of the storage claim.
  5. Click Create to create the persistent volume claim and generate a persistent volume.

Procedure (CLI)

To dynamically create a Manila CSI volume using the command-line interface (CLI):

  1. Create and save a file with the PersistentVolumeClaim object described by the following YAML:

    pvc-manila.yaml

    apiVersion: v1
    kind: PersistentVolumeClaim
    metadata:
      name: pvc-manila
    spec:
      accessModes: 1
        - ReadWriteMany
      resources:
        requests:
          storage: 10Gi
      storageClassName: csi-manila-gold 2

    1
    Use RWX if you want the persistent volume (PV) that fulfills this PVC to be mounted to multiple pods on multiple nodes in the cluster.
    2
    The name of the storage class that provisions the storage back end. Manila storage classes are provisioned by the Operator and have the csi-manila- prefix.
  2. Create the object you saved in the previous step by running the following command:

    $ oc create -f pvc-manila.yaml

    A new PVC is created.

  3. To verify that the volume was created and is ready, run the following command:

    $ oc get pvc pvc-manila

    The pvc-manila shows that it is Bound.

You can now use the new PVC to configure a pod.

Additional resources

4.11. Red Hat Virtualization CSI Driver Operator

4.11.1. Overview

OpenShift Container Platform is capable of provisioning persistent volumes (PVs) using the Container Storage Interface (CSI) driver for Red Hat Virtualization (RHV).

Familiarity with persistent storage and configuring CSI volumes is recommended when working with a Container Storage Interface (CSI) Operator and driver.

To create CSI-provisioned PVs that mount to RHV storage assets, OpenShift Container Platform installs the oVirt CSI Driver Operator and the oVirt CSI driver by default in the openshift-cluster-csi-drivers namespace.

  • The oVirt CSI Driver Operator provides a default StorageClass object that you can use to create Persistent Volume Claims (PVCs).
  • The oVirt CSI driver enables you to create and mount oVirt PVs.

4.11.2. About CSI

Storage vendors have traditionally provided storage drivers as part of Kubernetes. With the implementation of the Container Storage Interface (CSI), third-party providers can instead deliver storage plug-ins using a standard interface without ever having to change the core Kubernetes code.

CSI Operators give OpenShift Container Platform users storage options, such as volume snapshots, that are not possible with in-tree volume plug-ins.

4.11.3. oVirt CSI driver storage class

OpenShift Container Platform creates a default object of type StorageClass named ovirt-csi-sc which is used for creating dynamically provisioned persistent volumes.

To create additional storage classes for different configurations, create and save a file with the StorageClass object described by the following sample YAML:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: <storage-class-name>  1
  annotations:
    storageclass.kubernetes.io/is-default-class: "false"  2
provisioner: csi.ovirt.org
parameters:
  storageDomainName: <rhv-storage-domain-name> 3
  thinProvisioning: "true"  4
  csi.storage.k8s.io/fstype: ext4 5
1
Name of the storage class.
2
Set to false if the storage class is the default storage class in the cluster. If set to true, the existing default storage class must be edited and set to false.
3
RHV storage domain name to use.
4
Disk must be thin provisioned.
5
File system type to be created.

4.11.4. Creating a persistent volume on RHV

When you create a PersistentVolumeClaim (PVC) object, OpenShift Container Platform provisions a new persistent volume (PV) and creates a PersistentVolume object.

Prerequisites

  • You are logged in to a running OpenShift Container Platform cluster.
  • You provided the correct RHV credentials in ovirt-credentials secret.
  • You have installed the oVirt CSI driver.
  • You have defined at least one storage class.

Procedure

  • If you are using the we console to dynamically create a persistent volume on RHV:

    1. In the OpenShift Container Platform console, click StoragePersistent Volume Claims.
    2. In the persistent volume claims overview, click Create Persistent Volume Claim.
    3. Define the required options on the resulting page.
    4. Select the appropriate StorageClass object, which is ovirt-csi-sc by default.
    5. Enter a unique name for the storage claim.
    6. Select the access mode. Currently, RWO (ReadWriteOnce) is the only supported access mode.
    7. Define the size of the storage claim.
    8. Select the Volume Mode:

      Filesystem: Mounted into pods as a directory. This mode is the default.

      Block: Block device, without any file system on it

    9. Click Create to create the PersistentVolumeClaim object and generate a PersistentVolume object.
  • If you are using the command-line interface (CLI) to dynamically create a RHV CSI volume:

    1. Create and save a file with the PersistentVolumeClaim object described by the following sample YAML:

      pvc-ovirt.yaml

      apiVersion: v1
      kind: PersistentVolumeClaim
      metadata:
        name: pvc-ovirt
      spec:
        storageClassName: ovirt-csi-sc 1
        accessModes:
          - ReadWriteOnce
        resources:
          requests:
          storage: <volume size>  2
        volumeMode: <volume mode> 3

      1
      Name of the required storage class.
      2
      Volume size in GiB.
      3
      Supported options:
      • Filesystem: Mounted into pods as a directory. This mode is the default.
      • Block: Block device, without any file system on it.
    2. Create the object you saved in the previous step by running the following command:

      $ oc create -f pvc-ovirt.yaml
    3. To verify that the volume was created and is ready, run the following command:

      $ oc get pvc pvc-ovirt

      The pvc-ovirt shows that it is Bound.

4.12. VMware vSphere CSI Driver Operator

4.12.1. Overview

OpenShift Container Platform can provision persistent volumes (PVs) using the Container Storage Interface (CSI) VMware vSphere driver for Virtual Machine Disk (VMDK) volumes.

Important

vSphere CSI Driver Operator 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/.

Familiarity with persistent storage and configuring CSI volumes is recommended when working with a CSI Operator and driver.

To create CSI-provisioned persistent volumes (PVs) that mount to vSphere storage assets, OpenShift Container Platform, after this feature is enabled, installs the vSphere CSI Driver Operator and the vSphere CSI driver by default in the openshift-cluster-csi-drivers namespace.

  • vSphere CSI Driver Operator: After being enabled, the Operator provides a storage class, called thin-csi, that you can use to create persistent volumes claims (PVCs). The vSphere CSI Driver Operator supports dynamic volume provisioning by allowing storage volumes to be created on-demand, eliminating the need for cluster administrators to pre-provision storage.
  • vSphere CSI driver: The driver enables you to create and mount vSphere PVs.
Important

OpenShift Container Platform defaults to using an in-tree (non-CSI) plug-in to provision vSphere storage.

In future OpenShift Container Platform versions, volumes provisioned using existing in-tree plug-ins are planned for migration to their equivalent CSI driver. CSI automatic migration should be seamless. Migration does not change how you use all existing API objects, such as persistent volumes, persistent volume claims, and storage classes. For more information about migration, see CSI automatic migration.

After full migration, in-tree plug-ins will eventually be removed in future versions of OpenShift Container Platform.

4.12.2. About CSI

Storage vendors have traditionally provided storage drivers as part of Kubernetes. With the implementation of the Container Storage Interface (CSI), third-party providers can instead deliver storage plug-ins using a standard interface without ever having to change the core Kubernetes code.

CSI Operators give OpenShift Container Platform users storage options, such as volume snapshots, that are not possible with in-tree volume plug-ins.

Additional resources

4.12.3. Enabling the vSphere CSI Driver Operator

To enable the vSphere Container Storage Interface (CSI) Driver Operator, you must enable feature gates with the TechPreviewNoUpgrade feature set.

Procedure

  1. Enable feature gates with the TechPreviewNoUpgrade feature set (see NodesEnabling features using feature gates).

    Important

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

  2. Verify the cluster operator storage:

    $ oc get co storage
    NAME    VERSION                             AVAILABLE   PROGRESSING DEGRADED    SINCE
    storage 4.8.0-0.nightly-2021-04-30-201824   True        False       False       4h26m
    • AVAILABLE should be "True".
    • PROGRESSING should be "False".
    • DEGRADED should be "False".
  3. Verify the status of the pods in the openshift-cluster-csi-drivers namespace to ensure that they are running:

    $ oc get pod -n openshift-cluster-csi-drivers
    NAME                                                    READY   STATUS  RESTARTS    AGE
    vmware-vsphere-csi-driver-controller-5646dbbf54-cnsx7   9/9     Running 0           4h29m
    vmware-vsphere-csi-driver-node-ch22q                    3/3     Running 0           4h37m
    vmware-vsphere-csi-driver-node-gfjrb                    3/3     Running 0           4h37m
    vmware-vsphere-csi-driver-node-ktlmp                    3/3     Running 0           4h37m
    vmware-vsphere-csi-driver-node-lgksl                    3/3     Running 0           4h37m
    vmware-vsphere-csi-driver-node-vb4gv                    3/3     Running 0           4h37m
    vmware-vsphere-csi-driver-operator-7c7fc474c-p544t      1/1     Running 0           4h29m
NAME                                                    READY   STATUS  RESTARTS    AGE
azure-disk-csi-driver-controller-5949bf45fd-pm4qb       11/11   Running 0           39m
azure-disk-csi-driver-node-2tcxr                        3/3     Running 0           53m
azure-disk-csi-driver-node-2xjzm                        3/3     Running 0           53m
azure-disk-csi-driver-node-6wrgk                        3/3     Running 0           53m
azure-disk-csi-driver-node-frvx2                        3/3     Running 0           53m
azure-disk-csi-driver-node-lf5kb                        3/3     Running 0           53m
azure-disk-csi-driver-node-mqdhh                        3/3     Running 0           53m
azure-disk-csi-driver-operator-7d966fc6c5-x74x5         1/1     Running 0           44m
  1. Verify that the storage class is installed:

    $ oc get storageclass
    NAME            PROVISIONER                     RECLAIMPOLICY   VOLUMEBINDINGMODE       ALLOWVOLUMEEXPANSION    AGE
    thin (default)  kubernetes.io/vsphere-volume    Delete          Immediate               false                   5h43m
    thin-csi        csi.vsphere.vmware.com          Delete          WaitForFirstConsumer    false                   4h38m 1
    1
    vSphere storage class
NAME                        PROVISIONER                     RECLAIMPOLICY   VOLUMEBINDINGMODE       ALLOWVOLUMEEXPANSION    AGE
managed-premium (default)   kubernetes.io/azure-disk        Delete          WaitForFirstConsumer    true                    76m
managed-csi                 disk.csi.azure.com              Delete          WaitForFirstConsumer    true                    51m 1
1
Azure storage class

4.12.4. Additional resources