Red Hat build of MicroShift

Expanding persistent volume claims (PVCs) with a file system

To expand your storage capacity and meet growing data needs, you can resize existing volumes without recreating them.

Expanding persistent volume claims (PVCs) based on volume types that need file system resizing, such as Google Cloud Platform (GCP) persistent disk (PD), AWS Elastic Block Storage (EBS), and Cinder, 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 storage class has the allowVolumeExpansion field set to true.

For more information, see section Enabling volume expansion support.

Procedure

Edit the PVC and request a new size by editing spec.resources.requests. For example, the following expands the ebs PVC to 8 Gi:
Example PVC YAML file
```
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: ebs
spec:
  storageClass: "storageClassWithFlagSet"
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 8Gi
```
Where updating spec.resources.requests to a larger amount expands the PVC.

Verification

After the cloud provider object has finished resizing, the PVC is set to FileSystemResizePending.

Check the condition by running the following command:
```
$ oc describe pvc <pvc_name>
```

Next steps

When the cloud provider object has finished resizing, the PersistentVolume object reflects the newly requested size in PersistentVolume.Spec.Capacity. You can now create or recreate a new pod from the PVC to finish the file system resizing. After the pod is running, the newly requested size is available and the FileSystemResizePending condition is removed from the PVC.