ceph-csi/docs/expand-pvc.md
Madhu Rajanna 369fdb5051 Doc for cephfs expand PVC
Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>
2020-01-17 13:45:20 +00:00

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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 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.
- 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 resize 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
[$]kubectl edit pvc raw-block-pvc
```
Check PVC status after editing the pvc storage
```yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
annotations:
pv.kubernetes.io/bind-completed: "yes"
pv.kubernetes.io/bound-by-controller: "yes"
volume.beta.kubernetes.io/storage-provisioner: rbd.csi.ceph.com
creationTimestamp: "2019-12-19T05:56:02Z"
finalizers:
- kubernetes.io/pvc-protection
name: raw-block-pvc
namespace: default
resourceVersion: "7923"
selfLink: /api/v1/namespaces/default/persistentvolumeclaims/raw-block-pvc
uid: 54885275-7ca9-4b89-8e7e-c99f375d1174
spec:
accessModes:
- ReadWriteOnce
resources:
requests:
storage: 10Gi
storageClassName: csi-rbd-sc
volumeMode: Block
volumeName: pvc-54885275-7ca9-4b89-8e7e-c99f375d1174
status:
accessModes:
- ReadWriteOnce
capacity:
storage: 1Gi
conditions:
- lastProbeTime: null
lastTransitionTime: "2019-12-19T06:02:15Z"
message: Waiting for user to (re-)start a pod to finish file system resize of
volume on node.
status: "True"
type: FileSystemResizePending
phase: Bound
```
Now you can see the pvc stats as FileSystemResizePending, once the kubelet calls
the NodeExpandVolume to resize the PVC on node, the status conditions will be updated
and status.capacity.storage will be updated.
```bash
[$]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