Red Hat Summit Red Hat SummitSupportConsoleDevelopersStart a trialContact

Chapter 7. Expanding persistent volumes

7.1. Enabling volume expansion support
Copy link

Before you can expand persistent volumes, the StorageClass object must have the allowVolumeExpansion field set to true.

Procedure

  • Edit the StorageClass object and add the allowVolumeExpansion attribute by running the following command: 

    $ oc edit storageclass <storage_class_name>
    1
    Copy to Clipboard Toggle word wrap
    1
    Specifies the name of the storage class.

    The following example demonstrates adding this line at the bottom of the storage class configuration. 

    apiVersion: storage.k8s.io/v1
kind: StorageClass
...
parameters:
  type: gp2
reclaimPolicy: Delete
allowVolumeExpansion: true
    1
    Copy to Clipboard Toggle word wrap
    1
    Setting this attribute to true allows PVCs to be expanded after creation.

7.2. Expanding CSI volumes
Copy link

You can use the Container Storage Interface (CSI) to expand storage volumes after they have already been created.

Shrinking persistent volumes (PVs) is not supported.

Prerequisites

  • The underlying CSI driver supports resize. See "CSI drivers supported by Red Hat OpenShift Service on AWS" in the "Additional resources" section.
  • Dynamic provisioning is used.
  • The controlling StorageClass object has allowVolumeExpansion set to true. For more information, see "Enabling volume expansion support."

Procedure

  1. For the persistent volume claim (PVC), set .spec.resources.requests.storage to the desired new size.
  2. Watch the status.conditions field of the PVC to see if the resize has completed. Red Hat OpenShift Service on AWS adds the Resizing condition to the PVC during expansion, which is removed after expansion completes.

7.3. Expanding local volumes
Copy link

You can manually expand persistent volumes (PVs) and persistent volume claims (PVCs) created by using the local storage operator (LSO).

Procedure

  1. Expand the underlying devices. Ensure that appropriate capacity is available on these devices.
  2. Update the corresponding PV objects to match the new device sizes by editing the .spec.capacity field of the PV.
  3. For the storage class that is used for binding the PVC to PVet, set allowVolumeExpansion:true.
  4. For the PVC, set .spec.resources.requests.storage to match the new size.

Kubelet should automatically expand the underlying file system on the volume, if necessary, and update the status field of the PVC to reflect the new size.

Expanding PVCs based on volume types that need file system resizing, such as AWS Elastic Block Store EBS (EBS) is a two-step process. First, expand the volume objects in the cloud provider. Second, expand the file system on the node.

Expanding the file system on the node only happens when a new pod is started with the volume.

Prerequisites

  • The controlling StorageClass object must have allowVolumeExpansion set to true.

Procedure

  1. Edit the PVC and request a new size by editing spec.resources.requests. For example, the following expands the ebs PVC to 8 Gi: 

    kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: ebs
spec:
  storageClass: "storageClassWithFlagSet"
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 8Gi
    1
    Copy to Clipboard Toggle word wrap
    1
    Updating spec.resources.requests to a larger amount expands the PVC.

  2. After the cloud provider object has finished resizing, the PVC is set to FileSystemResizePending. Check the condition by entering the following command: 

    $ oc describe pvc <pvc_name>
    Copy to Clipboard Toggle word wrap
  3. When the cloud provider object has finished resizing, the PersistentVolume object reflects the newly requested size in PersistentVolume.Spec.Capacity. At this point, you can create or recreate a new pod from the PVC to finish the file system resizing. Once the pod is running, the newly requested size is available and the FileSystemResizePending condition is removed from the PVC.

If a resize request fails or remains in a pending state, you can try again by entering a different resize value in .spec.resources.requests.storage for the persistent volume claim (PVC). The new value must be larger than the original volume size.

If you are still having issues, use the following procedure to recover.

Procedure

If entering another smaller resize value in .spec.resources.requests.storage for the PVC does not work, do the following:

  1. Mark the persistent volume (PV) that is bound to the PVC with the Retain reclaim policy. Change persistentVolumeReclaimPolicy to Retain.
  2. Delete the PVC.
  3. Manually edit the PV and delete the claimRef entry from the PV specs to ensure that the newly created PVC can bind to the PV marked Retain. This marks the PV as Available.
  4. Re-create the PVC in a smaller size, or a size that can be allocated by the underlying storage provider.
  5. Set the volumeName field of the PVC to the name of the PV. This binds the PVC to the provisioned PV only.
  6. Restore the reclaim policy on the PV.
Back to top
Red Hat logoGithubredditYoutubeTwitter

Learn

Try, buy, & sell

Communities

About Red Hat Documentation

We help Red Hat users innovate and achieve their goals with our products and services with content they can trust. Explore our recent updates.

Making open source more inclusive

Red Hat is committed to replacing problematic language in our code, documentation, and web properties. For more details, see the Red Hat Blog.

About Red Hat

We deliver hardened solutions that make it easier for enterprises to work across platforms and environments, from the core datacenter to the network edge.

Theme

© 2025 Red Hat