ceph-csi/docs/expand-pvc.md

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# Dynamically Expand Volume
- [Dynamically Expand Volume](#dynamically-expand-volume)
- [Prerequisite](#prerequisite)
- [Expand RBD PVCs](#expand-rbd-pvcs)
- [Expand RBD Filesystem PVC](#expand-rbd-filesystem-pvc)
- [Expand RBD Block PVC](#expand-rbd-block-pvc)
- [Expand CephFS PVC](#expand-cephfs-pvc)
- [Expand CephFS Filesystem PVC](#expand-cephfs-filesystem-pvc)
## Prerequisite
- For filesystem expansion to be supported for your kubernetes cluster, the
kubernetes version running in your cluster should be >= v1.15 and for block
volume expand support the kubernetes version should be >=1.16. Also,
`ExpandCSIVolumes` feature gate has to be enabled for the volume expand
functionality to work.
- The controlling StorageClass must have `allowVolumeExpansion` set to `true`.
### Expand RBD PVCs
#### Expand RBD Filesystem PVC
pvc.yaml
```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
```bash
[$]kubectl exec -it csi-rbd-demo-pod sh
# df -h /var/lib/www/html
Filesystem Size Used Avail Use% Mounted on
/dev/rbd0 976M 2.6M 958M 1% /var/lib/www/html
```
- Now expand the PVC by editing the PVC (pvc.spec.resource.requests.storage)
```bash
[$]kubectl edit pvc rbd-pvc
```
Check PVC status after editing the pvc storage
```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: "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 expand the PVC on node, the `status conditions`
and `status` will be updated
```bash
[$]kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
rbd-pvc Bound pvc-efe688d6-a420-4041-900e-c5e19fd73ebf 10Gi RWO csi-rbd-sc 7m6s
```
- Now let us check the directory size inside the pod where PVC is mounted
```bash
[$]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
#### Expand RBD Block PVC
```bash
[$]kubectl get pvc raw-block-pvc -o yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
annotations:
pv.kubernetes.io/bind-completed: "yes"
pv.kubernetes.io/bound-by-controller: "yes"
volume.beta.kubernetes.io/storage-provisioner: rbd.csi.ceph.com
creationTimestamp: "2019-12-19T05:56:02Z"
finalizers:
- kubernetes.io/pvc-protection
name: raw-block-pvc
namespace: default
resourceVersion: "6370"
selfLink: /api/v1/namespaces/default/persistentvolumeclaims/raw-block-pvc
uid: 54885275-7ca9-4b89-8e7e-c99f375d1174
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 1Gi
storageClassName: csi-rbd-sc
volumeMode: Block
volumeName: pvc-54885275-7ca9-4b89-8e7e-c99f375d1174
status:
accessModes:
- ReadWriteOnce
capacity:
storage: 1Gi
phase: Bound
```
- Device size in pod using this PVC
```bash
[$]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 expand the PVC
To expand PVC, change `(pvc.spec.resource.requests.storage)` to the new size
which should be greater than the current size.
```bash
[$]kubectl edit pvc raw-block-pvc
```
Check PVC status after editing the pvc storage
```yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
annotations:
pv.kubernetes.io/bind-completed: "yes"
pv.kubernetes.io/bound-by-controller: "yes"
volume.beta.kubernetes.io/storage-provisioner: rbd.csi.ceph.com
creationTimestamp: "2019-12-19T05:56:02Z"
finalizers:
- kubernetes.io/pvc-protection
name: raw-block-pvc
namespace: default
resourceVersion: "7923"
selfLink: /api/v1/namespaces/default/persistentvolumeclaims/raw-block-pvc
uid: 54885275-7ca9-4b89-8e7e-c99f375d1174
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
storageClassName: csi-rbd-sc
volumeMode: Block
volumeName: pvc-54885275-7ca9-4b89-8e7e-c99f375d1174
status:
accessModes:
- ReadWriteOnce
capacity:
storage: 1Gi
conditions:
- lastProbeTime: null
lastTransitionTime: "2019-12-19T06:02:15Z"
message: Waiting for user to (re-)start a pod to finish file system resize of
volume on node.
status: "True"
type: FileSystemResizePending
phase: Bound
```
Now you can see the PVC stats as `FileSystemResizePending`, once the kubelet calls
the NodeExpandVolume to expand the PVC on node, the status conditions will be updated
and `status.capacity.storage` will be updated.
```bash
[$]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
```bash
[$]kubectl exec -it pod-with-raw-block-volume sh
sh-4.4# blockdev --getsize64 /dev/xvda
10737418240
```
rbd Block PVC is mounted at `/dev/xvda` of the pod, and the size is
`10737418240` bytes which is equal to `10Gib`
### Expand CephFS PVC
#### Expand CephFS Filesystem PVC
pvc.yaml
```yaml
apiVersion: v1
items:
- apiVersion: v1
kind: PersistentVolumeClaim
metadata:
annotations:
pv.kubernetes.io/bind-completed: "yes"
pv.kubernetes.io/bound-by-controller: "yes"
volume.beta.kubernetes.io/storage-provisioner: cephfs.csi.ceph.com
creationTimestamp: "2020-01-17T07:55:11Z"
finalizers:
- kubernetes.io/pvc-protection
name: csi-cephfs-pvc
namespace: default
resourceVersion: "5955"
selfLink: /api/v1/namespaces/default/persistentvolumeclaims/csi-cephfs-pvc
uid: b84d07c9-ea67-40b4-96b9-4a79669b1ccc
spec:
accessModes:
- ReadWriteMany
resources:
requests:
storage: 5Gi
storageClassName: csi-cephfs-sc
volumeMode: Filesystem
volumeName: pvc-b84d07c9-ea67-40b4-96b9-4a79669b1ccc
status:
accessModes:
- ReadWriteMany
capacity:
storage: 5Gi
phase: Bound
kind: List
metadata:
resourceVersion: ""
selfLink: ""
```
- mounted Filesystem size in pod using this PVC
```bash
[$]kubectl exec -it csi-cephfs-demo-pod sh
# df -h /var/lib/www
Filesystem Size Used Avail Use% Mounted on
10.108.149.216:6789:/volumes/csi/csi-vol-b0a1bc79-38fe-11ea-adb6-1a2797ee96de 5.0G 0 5.0G 0% /var/lib/www
```
- Now expand the PVC by editing the PVC (pvc.spec.resource.requests.storage)
```bash
[$]kubectl edit pvc csi-cephfs-pvc
```
Check PVC status after editing the PVC storage
```yaml
apiVersion: v1
items:
- apiVersion: v1
kind: PersistentVolumeClaim
metadata:
annotations:
pv.kubernetes.io/bind-completed: "yes"
pv.kubernetes.io/bound-by-controller: "yes"
volume.beta.kubernetes.io/storage-provisioner: cephfs.csi.ceph.com
creationTimestamp: "2020-01-17T07:55:11Z"
finalizers:
- kubernetes.io/pvc-protection
name: csi-cephfs-pvc
namespace: default
resourceVersion: "6902"
selfLink: /api/v1/namespaces/default/persistentvolumeclaims/csi-cephfs-pvc
uid: b84d07c9-ea67-40b4-96b9-4a79669b1ccc
spec:
accessModes:
- ReadWriteMany
resources:
requests:
storage: 10Gi
storageClassName: csi-cephfs-sc
volumeMode: Filesystem
volumeName: pvc-b84d07c9-ea67-40b4-96b9-4a79669b1ccc
status:
accessModes:
- ReadWriteMany
capacity:
storage: 10Gi
phase: Bound
kind: List
metadata:
resourceVersion: ""
selfLink: ""
```
Now you can see the PVC status capacity storage is updated with request size
```bash
[$]kubectl get pvc
NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE
csi-cephfs-pvc Bound pvc-b84d07c9-ea67-40b4-96b9-4a79669b1ccc 10Gi RWX csi-cephfs-sc 6m26s
```
- Now let us check the directory size inside the pod where PVC is mounted
```bash
[$]kubectl exec -it csi-cephfs-demo-pod sh
# df -h /var/lib/www
Filesystem Size Used Avail Use% Mounted on
10.108.149.216:6789:/volumes/csi/csi-vol-b0a1bc79-38fe-11ea-adb6-1a2797ee96de 10G 0 10G 0% /var/lib/www
```
now you can see the size of `/var/lib/www` is updated from 5G to 10G