ceph-csi/docs/resize-pvc.md

Resize RBD PVCs

For filesystem resize to be supported for your kubernetes cluster, the kubernetes version running in your cluster should be >= v1.15 and for block volume resize support the kubernetes version should be >=1.16. Also, ExpandCSIVolumes feature gate has to be enabled for the volume resize functionality to work.

• Resize RBD PVCs
  • Filesystem resize on RBD filesystem volume mode PVCs
  • Resize Block PVC

Filesystem resize on RBD filesystem volume mode PVCs

pvc.yaml

apiVersion: v1
items:
- apiVersion: v1
  kind: PersistentVolumeClaim
  metadata:
    annotations:
      pv.kubernetes.io/bind-completed: "yes"
      pv.kubernetes.io/bound-by-controller: "yes"
      volume.beta.kubernetes.io/storage-provisioner: rbd.csi.ceph.com
    creationTimestamp: "2019-12-19T05:44:45Z"
    finalizers:
    - kubernetes.io/pvc-protection
    name: rbd-pvc
    namespace: default
    resourceVersion: "3557"
    selfLink: /api/v1/namespaces/default/persistentvolumeclaims/rbd-pvc
    uid: efe688d6-a420-4041-900e-c5e19fd73ebf
  spec:
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 1Gi
    storageClassName: csi-rbd-sc
    volumeMode: Filesystem
    volumeName: pvc-efe688d6-a420-4041-900e-c5e19fd73ebf
  status:
    accessModes:
    - ReadWriteOnce
    capacity:
      storage: 1Gi
    phase: Bound
kind: List
metadata:
  resourceVersion: ""
  selfLink: ""

• mounted Filesystem size in pod using this PVC

[$]kubectl exec -it csi-rbd-demo-pod sh
# df -h /var/lib/www/html
Filesystem      Size  Used Avail Use% Mounted on
/dev/rbd0       976M  2.6M  958M   1% /var/lib/www/html
#

• Now resize the PVC by editing the PVC (pvc.spec.resource.requests.storage)

[$]kubectl edit pvc rbd-pvc

Check PVC status after editing the pvc storage

apiVersion: v1
items:
- apiVersion: v1
  kind: PersistentVolumeClaim
  metadata:
    annotations:
      pv.kubernetes.io/bind-completed: "yes"
      pv.kubernetes.io/bound-by-controller: "yes"
      volume.beta.kubernetes.io/storage-provisioner: rbd.csi.ceph.com
    creationTimestamp: "2019-12-19T05:44:45Z"
    finalizers:
    - kubernetes.io/pvc-protection
    name: rbd-pvc
    namespace: default
    resourceVersion: "4773"
    selfLink: /api/v1/namespaces/default/persistentvolumeclaims/rbd-pvc
    uid: efe688d6-a420-4041-900e-c5e19fd73ebf
  spec:
    accessModes:
    - ReadWriteOnce
    resources:
      requests:
        storage: 10Gi
    storageClassName: csi-rbd-sc
    volumeMode: Filesystem
    volumeName: pvc-efe688d6-a420-4041-900e-c5e19fd73ebf
  status:
    accessModes:
    - ReadWriteOnce
    capacity:
      storage: 1Gi
    conditions:
    - lastProbeTime: null
      lastTransitionTime: "2019-12-19T05:49:39Z"
      message: Waiting for user to (re-)start a pod to finish file system resize of
        volume on node.
      status: "True"
      type: FileSystemResizePending
    phase: Bound
kind: List
metadata:
  resourceVersion: ""
  selfLink: ""

Now you can see the pvc status as FileSystemResizePending, once the kubelet calls the NodeExpandVolume to resize the PVC on node, the status conditions and status will be updated

[$]kubectl get pvc
NAME      STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS      AGE
rbd-pvc   Bound    pvc-efe688d6-a420-4041-900e-c5e19fd73ebf   10Gi       RWO            csi-rbd-sc   7m6s

• Now let us check the directory size inside the pod where PVC is mounted

[$]kubectl exec -it csi-rbd-demo-pod sh
# df -h /var/lib/www/html
Filesystem      Size  Used Avail Use% Mounted on
/dev/rbd0       9.9G  4.5M  9.8G   1% /var/lib/www/html

now you can see the size of /var/lib/www/html is updated from 976M to 9.9G

Resize Block PVC

[$]kubectl get pvc raw-block-pvc -o yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  annotations:
    pv.kubernetes.io/bind-completed: "yes"
    pv.kubernetes.io/bound-by-controller: "yes"
    volume.beta.kubernetes.io/storage-provisioner: rbd.csi.ceph.com
  creationTimestamp: "2019-12-19T05:56:02Z"
  finalizers:
  - kubernetes.io/pvc-protection
  name: raw-block-pvc
  namespace: default
  resourceVersion: "6370"
  selfLink: /api/v1/namespaces/default/persistentvolumeclaims/raw-block-pvc
  uid: 54885275-7ca9-4b89-8e7e-c99f375d1174
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi
  storageClassName: csi-rbd-sc
  volumeMode: Block
  volumeName: pvc-54885275-7ca9-4b89-8e7e-c99f375d1174
status:
  accessModes:
  - ReadWriteOnce
  capacity:
    storage: 1Gi
  phase: Bound

• Device size in pod using this PVC

[$]kubectl exec -it pod-with-raw-block-volume sh
sh-4.4# blockdev --getsize64 /dev/xvda
1073741824

rbd Block PVC is mounted at /dev/xvda of the pod, and the size is 1073741824 bytes which is equal to 1Gib

• Now resize the PVC

To resize PVC, change (pvc.spec.resource.requests.storage) to the new size which should be greater than the current size.

[$]kubectl edit pvc raw-block-pvc

Check PVC status after editing the pvc storage

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  annotations:
    pv.kubernetes.io/bind-completed: "yes"
    pv.kubernetes.io/bound-by-controller: "yes"
    volume.beta.kubernetes.io/storage-provisioner: rbd.csi.ceph.com
  creationTimestamp: "2019-12-19T05:56:02Z"
  finalizers:
  - kubernetes.io/pvc-protection
  name: raw-block-pvc
  namespace: default
  resourceVersion: "7923"
  selfLink: /api/v1/namespaces/default/persistentvolumeclaims/raw-block-pvc
  uid: 54885275-7ca9-4b89-8e7e-c99f375d1174
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi
  storageClassName: csi-rbd-sc
  volumeMode: Block
  volumeName: pvc-54885275-7ca9-4b89-8e7e-c99f375d1174
status:
  accessModes:
  - ReadWriteOnce
  capacity:
    storage: 1Gi
  conditions:
  - lastProbeTime: null
    lastTransitionTime: "2019-12-19T06:02:15Z"
    message: Waiting for user to (re-)start a pod to finish file system resize of
      volume on node.
    status: "True"
    type: FileSystemResizePending
  phase: Bound

Now you can see the pvc stats as FileSystemResizePending, once the kubelet calls the NodeExpandVolume to resize the PVC on node, the status conditions will be updated and status.capacity.storage will be updated.

[$]kubectl get pvc
NAME      STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS      AGE
raw-block-pvc   Bound    pvc-efe688d6-a420-4041-900e-c5e19fd73ebf   10Gi       RWO            csi-rbd-sc   7m6s

Device size in pod using this PVC

[$]kubectl exec -it pod-with-raw-block-volume sh
sh-4.4# blockdev --getsize64 /dev/xvda
10737418240

rbd Block PVC is mounted at /dev/xvda of the pod, and the size is 10737418240 bytes which is equal to 10Gib