Expand PV

To expand the capacity of a PV, you only need to modify the field storage in its corresponding PVC.

Prerequisite

The StorageClass must have allowVolumeExpansion set to true. The default StorageClass iomesh-csi-driver already does this. If a StorageClass is created and configured with custom parameters, verify that its allowVolumeExpansion is set to true.

Procedure

The following example assumes a YAML config pvc.yaml that points to a PVC iomesh-example-pvc with a capacity of 10Gi.

# Source: pvc.yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: iomesh-example-pvc
spec:
  storageClassName: iomesh-csi-driver
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi # The original capacity of the PVC.

1. Get the PVC.

   kubectl get pvc iomesh-example-pvc
   

   If successful, you should see output below:

   NAME                 STATUS   VOLUME                                     CAPACITY    ACCESS MODES   STORAGECLASS                AGE
   iomesh-example-pvc   Bound    pvc-b2fc8425-9dbc-4204-8240-41cb4a7fa8ca   10Gi        RWO            iomesh-csi-driver           11m
   

2. Access pvc.yaml. Then set the field storage to a new value.

   apiVersion: v1
   kind: PersistentVolumeClaim
   metadata:
     name: iomesh-example-pvc
   spec:
     storageClassName: iomesh-csi-driver
     accessModes:
       - ReadWriteOnce
     resources:
       requests:
         storage: 20Gi # The new value must be greater than the original one.
   

3. Apply the modification.

   kubectl apply -f pvc.yaml
   

4. View the PVC and its corresponding PV.

   NOTE: The PV capacity will be changed to the new value, but the capacity value in the PVC will remain the same until it is actually used by the pod.

   kubectl get pvc iomesh-example-pvc 
   

   If successful, you should see output below.

   NAME                 STATUS   VOLUME                                     CAPACITY    ACCESS MODES   STORAGECLASS                AGE
   iomesh-example-pvc   Bound    pvc-b2fc8425-9dbc-4204-8240-41cb4a7fa8ca   10Gi        RWO            iomesh-csi-driver           11m
   

5. Verify that the PV capacity was expanded. You can find the PV name from the PVC output.

   kubectl get pv pvc-b2fc8425-9dbc-4204-8240-41cb4a7fa8ca # The PV name you get in Step 4.
   

   If successful, you should see output below:

   NAME                                       CAPACITY   RECLAIM POLICY   STATUS   CLAIM                       STORAGECLASS
   pvc-b2fc8425-9dbc-4204-8240-41cb4a7fa8ca   20Gi       Delete           Bound    default/iomesh-example-pvc  iomesh-csi-driver