一.问题描述
动态扩容PVC的时候报错(kubectl edit pvc pvcname)：“error: persistentvolumeclaims "pvvolume" could not be patched: persistentvolumeclaims "pvvolume" is forbidden: only dynamically provisioned pvc can be resized and the storageclass that provisions the pvc must support resize”
二.解决方法
配置一个10M大小的pvc，关于PVC的详细内容，请查看博客《Kubernetes(k8s)存储管理之数据卷volumes(四)：持久卷Persistent Volume》https://www.cnblogs.com/renshengdezheli/p/16972289.html
[student@vms20 ~]$ vim 13.yaml [student@vms20 ~]$ cat 13.yaml apiVersion: v1 kind: PersistentVolumeClaim metadata: name: pvvolume spec: accessModes: - ReadWriteOnce volumeMode: Filesystem resources: requests: storage: 10Mi storageClassName: csi-hostpath-sc 创建PVC
[student@vms20 ~]$ kubectl apply -f 13.yaml persistentvolumeclaim/pvvolume created [student@vms20 ~]$ kubectl get pvc NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE pvvolume Bound pvc-09b90084-aa96-4e10-a124-79c9af98ccc0 10Mi RWO csi-hostpath-sc 10s [student@vms20 ~]$ kubectl get pvc -o wide NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE VOLUMEMODE pvvolume Bound pvc-09b90084-aa96-4e10-a124-79c9af98ccc0 10Mi RWO csi-hostpath-sc 14s Filesystem 把PVC挂载到pod上，并创建pod
[student@vms20 ~]$ vim 13pod.yaml [student@vms20 ~]$ cat 13pod.yaml apiVersion: v1 kind: Pod metadata: name: web-server spec: containers: - name: myfrontend image: nginx imagePullPolicy: IfNotPresent volumeMounts: - mountPath: "/usr/share/nginx/html" name: mypvc volumes: - name: mypvc persistentVolumeClaim: claimName: pvvolume [student@vms20 ~]$ kubectl apply -f 13pod.yaml pod/web-server created [student@vms20 ~]$ kubectl get pod | grep web-server web-server 1/1 Running 0 20s 修改pvc的容量为70Mi，PVC动态扩容报错如下：
[student@vms20 ~]$ kubectl get pvc NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE pvvolume Bound pvc-09b90084-aa96-4e10-a124-79c9af98ccc0 10Mi RWO csi-hostpath-sc 14m #动态扩容PVC报错 [student@vms20 ~]$ kubectl edit pvc pvvolume --record Flag --record has been deprecated, --record will be removed in the future error: persistentvolumeclaims "pvvolume" could not be patched: persistentvolumeclaims "pvvolume" is forbidden: only dynamically provisioned pvc can be resized and the storageclass that provisions the pvc must support resize You can run `kubectl replace -f /tmp/kubectl-edit-857302533.yaml` to try this update again. 解决方法：要支持动态扩容需要满足两个条件：
- 后端底层存储支持卷扩展（后端存储保证足够资源） ；
- 需要在StorageClass对象中设置allowVolumeExpansion为true。
可以看到storageclass此时ALLOWVOLUMEEXPANSION参数为false。
[student@vms20 ~]$ kubectl get storageclass NAME PROVISIONER RECLAIMPOLICY VOLUMEBINDINGMODE ALLOWVOLUMEEXPANSION AGE csi-hostpath-sc hostpath.csi.k8s.io Delete Immediate false 277d 编辑csi-hostpath-sc，把ALLOWVOLUMEEXPANSION修改为true
#添加参数allowVolumeExpansion: true ####### # Please edit the object below. Lines beginning with a '#' will be ignored, # and an empty file will abort the edit. If an error occurs while saving this file will be # reopened with the relevant failures. # allowVolumeExpansion: true apiVersion: storage.k8s.io/v1 kind: StorageClass metadata: annotations: kubectl.kubernetes.io/last-applied-configuration: | {"apiVersion":"storage.k8s.io/v1","kind":"StorageClass","metadata":{"annotations":{},"name":"csi-hostpath-sc"},"parameters":{"archiveOnDelete":"false"},"provisioner":"hostpath.csi.k8s.io"} creationTimestamp: "2021-11-04T10:54:48Z" name: csi-hostpath-sc resourceVersion: "177035" uid: a594f8fd-9c3d-49d3-85a4-085c89a7bb1c parameters: archiveOnDelete: "false" provisioner: hostpath.csi.k8s.io reclaimPolicy: Delete volumeBindingMode: Immediate ####### [student@vms20 ~]$ kubectl edit storageclass csi-hostpath-sc storageclass.storage.k8s.io/csi-hostpath-sc edited #现在ALLOWVOLUMEEXPANSION变为true了 [student@vms20 ~]$ kubectl get storageclass NAME PROVISIONER RECLAIMPOLICY VOLUMEBINDINGMODE ALLOWVOLUMEEXPANSION AGE csi-hostpath-sc hostpath.csi.k8s.io Delete Immediate true 277d 再次PVC动态扩容
[student@vms20 ~]$ kubectl get pvc NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE pvvolume Bound pvc-09b90084-aa96-4e10-a124-79c9af98ccc0 10Mi RWO csi-hostpath-sc 25m #现在pvc动态扩容：将所有位置的capacity:storage:10Mi修改为70Mi [student@vms20 ~]$ kubectl edit pvc pvvolume --record Flag --record has been deprecated, --record will be removed in the future persistentvolumeclaim/pvvolume edited #PVC动态扩容成功 [student@vms20 ~]$ kubectl get pvc NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS AGE pvvolume Bound pvc-09b90084-aa96-4e10-a124-79c9af98ccc0 70Mi RWO csi-hostpath-sc 27m 自此，PVC动态扩容成功。
