User Guide: Resizing (Expanding) Volumes

July 21, 2026 · View on GitHub

RawFile LocalPV supports online expansion of volumes — the backing file, loop device and filesystem are grown live, with no pod restart or remount. Shrinking is not supported.

Before you begin

  • Resize must be enabled in the chart (default): capabilities.resize.enabled=true (this deploys the controller component with the csi-resizer sidecar).
  • The StorageClass must allow expansion:
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: rawfile-localpv
provisioner: rawfile.csi.openebs.io
volumeBindingMode: WaitForFirstConsumer
reclaimPolicy: Delete
allowVolumeExpansion: true      # ← required for resize
parameters:
  csi.storage.k8s.io/fstype: ext4
  • Online filesystem growth works for ext4, xfs and btrfs (all supported fsTypes).
  • Enough free capacity must exist in the volume's storage pool on its node.

Step 1 — Increase the PVC size

Edit the PVC's spec.resources.requests.storage to the new (larger) size:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: app-data
spec:
  storageClassName: rawfile-localpv
  accessModes: [ReadWriteOnce]
  resources:
    requests:
      storage: 20Gi        # was 10Gi

kubectl apply -f pvc.yaml

Or patch in place:

kubectl patch pvc app-data \
  -p '{"spec":{"resources":{"requests":{"storage":"20Gi"}}}}'

Step 2 — Watch the expansion complete

kubectl get pvc app-data -w
# NAME       STATUS   VOLUME      CAPACITY   ACCESS MODES   STORAGECLASS
# app-data   Bound    pvc-xxxxx   10Gi       RWO            rawfile-localpv
# app-data   Bound    pvc-xxxxx   20Gi       RWO            rawfile-localpv

Check events and conditions if it takes long:

kubectl describe pvc app-data

Under the hood: the csi-resizer calls the controller, which forwards the request over the internal gRPC channel to the node that owns the volume; the node grows the backing file, resizes the loop device and expands the filesystem online.

Step 3 — Verify inside the pod

kubectl exec app -- df -hT /data
# Filesystem     Type  Size  Used Avail Use% Mounted on
# /dev/loop3     ext4   20G  1.1G   18G   6% /data

No pod restart is needed — the new capacity is visible immediately after the resize completes.

Block-mode volumes

Block volumes (volumeMode: Block) are also expandable. If the volume is currently unstaged (no pod using it), only the backing file is grown and node-side expansion is skipped; the device shows the new size the next time it is attached. The application inside the pod is responsible for recognizing the larger device.

Limitations

ItemStatus
Online expansion (ext4/xfs/btrfs)✅
Expansion while pod is running✅
Shrinking (online or offline)❌ not supported — requests to reduce size are rejected by Kubernetes
Expansion beyond pool free space❌ fails with Not enough disk space (RESOURCE_EXHAUSTED)

Troubleshooting

SymptomFix
PVC capacity never updatesIs allowVolumeExpansion: true on the SC? Is the controller Deployment running (capabilities.resize.enabled)? Check kubectl -n openebs logs deploy/<release>-controller.
Not enough disk spaceThe volume's pool on its node lacks free capacity — free space or grow the underlying disk. Check rawfile_pool_remaining_capacity_bytes.
Resizing capabilities are disabledSet capabilities.resize.enabled=true in chart values and upgrade the release.
Filesystem size unchanged but PV shows new sizeNode-side expansion pending — ensure the pod's node plugin is healthy; kubelet triggers NodeExpandVolume on the mounted node.