velero: ARK backup failed with efs provisioner

I used efs provisioner for creating PV for PO and ark can not backup PV.

This is yaml file to create nginx with efs pv.

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---
apiVersion: v1
kind: Namespace
metadata:
  name: nginx-example-efs
  labels:
    app: nginx-example-efs

---
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: nginx-logs
  namespace: nginx-example-efs
  labels:
    app: nginx-example-efs
spec:
  storageClassName: aws-efs-2
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi

---
apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: nginx-deployment
  namespace: nginx-example-efs
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: nginx-example-efs
    spec:
      volumes:
        - name: nginx-logs
          persistentVolumeClaim:
           claimName: nginx-logs
      containers:
      - image: nginx:1.7.9
        name: nginx
        ports:
        - containerPort: 80
        volumeMounts:
          - mountPath: "/var/log/nginx"
            name: nginx-logs
            readOnly: false
      tolerations:
        - key: "type"
          effect: "NoSchedule"
          value: "MEM"

---
apiVersion: v1
kind: Service
metadata:
  labels:
    app: nginx-example-efs
  name: my-nginx
  namespace: nginx-example-efs
spec:
  ports:
  - port: 80
    targetPort: 80
  selector:
    app: nginx-example-efs
  type: ClusterIP

Log:

Name:         nginx-example-efs
Namespace:    heptio-ark
Labels:       <none>
Annotations:  <none>

Namespaces:
  Included:  *
  Excluded:  <none>

Resources:
  Included:        *
  Excluded:        <none>
  Cluster-scoped:  auto

Label selector:  app=nginx-example-efs

Snapshot PVs:  auto

TTL:  720h0m0s

Hooks:  <none>

Phase:  Completed

Backup Format Version:  1

Expiration:  2018-07-25 14:42:49 +0700 +07

Validation errors:  <none>

Persistent Volumes: <none included>

time="2018-06-25T07:42:50Z" level=info msg="PersistentVolume is not a supported volume type for snapshots, skipping." backup=heptio-ark/nginx-example-efs group=v1 groupResource=persistentvolumeclaims logSource="pkg/backup/item_backupper.go:307" name=pvc-b33e8de0-784a-11e8-957d-12dd8b001c9e namespace=nginx-example