PersistentVolumes created using the provided StorageClasses can be resized
and Kubernetes since v1.11 supports this.
Note
PersistentVolumes can only be expanded, not reduced in size.
$ kubectl get storageclass
NAME PROVISIONER RECLAIMPOLICY VOLUMEBINDINGMODE ALLOWVOLUMEEXPANSION AGE
b1.sr-r3-nvme-1000 (default) cinder.csi.openstack.org Retain Immediate true 6d3h
b1.sr-r3-nvme-2500 cinder.csi.openstack.org Retain Immediate true 6d3h
b1.sr-r3-nvme-5000 cinder.csi.openstack.org Retain Immediate true 6d3h
b1.standard cinder.csi.openstack.org Retain Immediate true 6d3h
To initiate a resize, edit the PersistentVolumeClaim and set
spec.resources.requests.storage to an increased size.
$ kubectl edit pvc/test-persistentvolumeclaim
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: cinder.csi.openstack.org
volume.kubernetes.io/storage-provisioner: cinder.csi.openstack.org
creationTimestamp: "2024-01-31T22:42:26Z"
finalizers:
- kubernetes.io/pvc-protection
name: test-persistentvolumeclaim
namespace: default
resourceVersion: "1156755"
uid: bca8b8ef-01b2-408e-aba6-bf9bef249e84
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 3Gi
storageClassName: b1.sr-r3-nvme-1000
volumeMode: Filesystem
volumeName: pvc-bca8b8ef-01b2-408e-aba6-bf9bef249e84
Once this has been done, there will be several failed events. This is because online resizing is not permitted and a pod has the PV mounted.
$ kubectl get events
LAST SEEN TYPE REASON OBJECT MESSAGE
5s Warning ExternalExpanding persistentvolumeclaim/test-persistentvolumeclaim waiting for an external controller to expand this PVC
2s Normal Resizing persistentvolumeclaim/test-persistentvolumeclaim External resizer is resizing volume pvc-bca8b8ef-01b2-408e-aba6-bf9bef249e84
2s Warning VolumeResizeFailed persistentvolumeclaim/test-persistentvolumeclaim resize volume "pvc-bca8b8ef-01b2-408e-aba6-bf9bef249e84" by resizer "cinder.csi.openstack.org" failed: rpc error: code = Internal desc = Could not resize volume "127fd890-8bb5-4962-92f6-bf498a8881c5" to size 2: Expected HTTP response code [202] when accessing [POST https://api.catalystcloud.nz:8776/v3/b6170e3eab4d44428c879485de7bee98/volumes/127fd890-8bb5-4962-92f6-bf498a8881c5/action], but got 406 instead
To complete the resize, re-create the pod that has the PersistentVolume mounted; either
by deleting it and re-creating or by scaling the associated deployment down and back up.
In this example, we do not have a Deployment, so we will delete and re-create the pod.
$ kubectl delete -f pvc1-pod.yaml
pod "pod-pv-test" deleted
$ kubectl create -f pvc1-pod.yaml
pod/pod-pv-test created
When the PersistentVolume is mounted on the new pod, it will be resized by
Cinder CSI, and the kubelet will resize the filesystem. Then the pod will be
started with the new size.
We can see these events and verify the size is reflected inside the new pod:
$ kubectl get events
LAST SEEN TYPE REASON OBJECT MESSAGE
2m57s Normal Killing pod/pod-pv-test Stopping container test-storage-container
2m28s Warning ExternalExpanding persistentvolumeclaim/test-persistentvolumeclaim waiting for an external controller to expand this PVC
2m28s Normal Resizing persistentvolumeclaim/test-persistentvolumeclaim External resizer is resizing volume pvc-bca8b8ef-01b2-408e-aba6-bf9bef249e84
2m26s Normal FileSystemResizeRequired persistentvolumeclaim/test-persistentvolumeclaim Require file system resize of volume on node
2m15s Normal Scheduled pod/pod-pv-test Successfully assigned default/pod-pv-test to cluster1-afjuly77v4gr-node-0
2m7s Normal SuccessfulAttachVolume pod/pod-pv-test AttachVolume.Attach succeeded for volume "pvc-bca8b8ef-01b2-408e-aba6-bf9bef249e84"
2m5s Normal FileSystemResizeSuccessful persistentvolumeclaim/test-persistentvolumeclaim MountVolume.NodeExpandVolume succeeded for volume "pvc-bca8b8ef-01b2-408e-aba6-bf9bef249e84" cluster1-afjuly77v4gr-node-0
2m5s Normal FileSystemResizeSuccessful pod/pod-pv-test MountVolume.NodeExpandVolume succeeded for volume "pvc-bca8b8ef-01b2-408e-aba6-bf9bef249e84" cluster1-afjuly77v4gr-node-0
2m4s Normal Pulling pod/pod-pv-test Pulling image "nginx:latest"
2m3s Normal Pulled pod/pod-pv-test Successfully pulled image "nginx:latest" in 1.579627165s (1.579648593s including waiting)
2m3s Normal Created pod/pod-pv-test Created container test-storage-container
2m2s Normal Started pod/pod-pv-test Started container test-storage-container
$ kubectl exec -it pod-pv-test -- /bin/bash
root@pod-pv-test:/# mount | grep data
/dev/vdd on /data type ext4 (rw,relatime,seclabel,mb_optimize_scan=0)
root@pod-pv-test:/# df -h /data
Filesystem Size Used Avail Use% Mounted on
/dev/vdd 3.0G 24K 3.0G 1% /data