I am trying to use the VolumeSnapshot backup mechanism promoted in kubernetes to beta from 1.17.

Here is my scenario:

Create the nginx deployment and the PVC used by it

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80
        volumeMounts:
        - name: my-pvc
          mountPath: /root/test
      volumes:
        - name: my-pvc
          persistentVolumeClaim:
            claimName: nginx-pvc

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  finalizers: null
  labels:
    name: nginx-pvc
  name: nginx-pvc
  namespace: default
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 8Gi
  storageClassName: premium-rwo

Exec into the running nginx container, cd into the PVC mounted path and create some files

▶ k exec -it nginx-deployment-84765795c-7hz5n bash
root@nginx-deployment-84765795c-7hz5n:/# cd /root/test
root@nginx-deployment-84765795c-7hz5n:~/test# touch {1..10}.txt
root@nginx-deployment-84765795c-7hz5n:~/test# ls
1.txt  10.txt  2.txt  3.txt  4.txt  5.txt  6.txt  7.txt  8.txt	9.txt  lost+found
root@nginx-deployment-84765795c-7hz5n:~/test#

Create the following VolumeSnapshot using as source the nginx-pvc

apiVersion: snapshot.storage.k8s.io/v1beta1
kind: VolumeSnapshot
metadata:
  namespace: default
  name: nginx-volume-snapshot
spec:
  volumeSnapshotClassName: pd-retain-vsc
  source:
    persistentVolumeClaimName: nginx-pvc

The VolumeSnapshotClass used is the following

apiVersion: snapshot.storage.k8s.io/v1beta1
deletionPolicy: Retain
driver: pd.csi.storage.gke.io
kind: VolumeSnapshotClass
metadata:
  creationTimestamp: "2020-09-25T09:10:16Z"
  generation: 1
  name: pd-retain-vsc

and wait until it becomes readyToUse: true

apiVersion: v1
items:
- apiVersion: snapshot.storage.k8s.io/v1beta1
  kind: VolumeSnapshot
  metadata:
    creationTimestamp: "2020-11-04T09:38:00Z"
    finalizers:
    - snapshot.storage.kubernetes.io/volumesnapshot-as-source-protection
    generation: 1
    name: nginx-volume-snapshot
    namespace: default
    resourceVersion: "34170857"
    selfLink: /apis/snapshot.storage.k8s.io/v1beta1/namespaces/default/volumesnapshots/nginx-volume-snapshot
    uid: ce1991f8-a44c-456f-8b2a-2e12f8df28fc
  spec:
    source:
      persistentVolumeClaimName: nginx-pvc
    volumeSnapshotClassName: pd-retain-vsc
  status:
    boundVolumeSnapshotContentName: snapcontent-ce1991f8-a44c-456f-8b2a-2e12f8df28fc
    creationTime: "2020-11-04T09:38:02Z"
    readyToUse: true
    restoreSize: 8Gi
kind: List
metadata:
  resourceVersion: ""
  selfLink: ""

Delete the nginx deployment and the initial PVC

▶ k delete pvc,deploy --all
persistentvolumeclaim "nginx-pvc" deleted
deployment.apps "nginx-deployment" deleted

Create a new PVC, using the previously created VolumeSnapshot as its dataSource

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  finalizers: null
  labels:
    name: nginx-pvc-restored
  name: nginx-pvc-restored
  namespace: default
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 8Gi
  dataSource:
    name: nginx-volume-snapshot
    kind: VolumeSnapshot
    apiGroup: snapshot.storage.k8s.io

▶ k create -f nginx-pvc-restored.yaml
persistentvolumeclaim/nginx-pvc-restored created

▶ k get pvc
NAME                 STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS   AGE
nginx-pvc-restored   Bound    pvc-56d0a898-9f65-464f-8abf-90fa0a58a048   8Gi        RWO            standard       39s

Set the name of the new (restored) PVC to the nginx deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
spec:
  selector:
    matchLabels:
      app: nginx
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.14.2
        ports:
        - containerPort: 80
        volumeMounts:
        - name: my-pvc
          mountPath: /root/test
      volumes:
        - name: my-pvc
          persistentVolumeClaim:
            claimName: nginx-pvc-restored

and create the Deployment again

▶ k create -f nginx-deployment-restored.yaml
deployment.apps/nginx-deployment created

cd into the PVC mounted directory. It should contain the previously created files but its empty

▶ k exec -it nginx-deployment-67c7584d4b-l7qrq bash
root@nginx-deployment-67c7584d4b-l7qrq:/# cd /root/test
root@nginx-deployment-67c7584d4b-l7qrq:~/test# ls
lost+found
root@nginx-deployment-67c7584d4b-l7qrq:~/test#

▶ k version
Client Version: version.Info{Major:"1", Minor:"17", GitVersion:"v1.17.12", GitCommit:"5ec472285121eb6c451e515bc0a7201413872fa3", GitTreeState:"clean", BuildDate:"2020-09-16T13:39:51Z", GoVersion:"go1.13.15", Compiler:"gc", Platform:"darwin/amd64"}
Server Version: version.Info{Major:"1", Minor:"17+", GitVersion:"v1.17.12-gke.1504", GitCommit:"17061f5bd4ee34f72c9281d49f94b4f3ac31ac25", GitTreeState:"clean", BuildDate:"2020-10-19T17:00:22Z", GoVersion:"go1.13.15b4", Compiler:"gc", Platform:"linux/amd64"}