Kubernetes statefulset replication

Question

I am using kubernetes statefulset for my mongodb and influxdb.

In summary, StatefulSets provide the following advantages when compared to Deployment objects: Ordered numbers for each Pod. The first Pod can be a primary, which makes it a good choice when creating a replicated database setup, which handles both reading and writing. Other Pods act as replicas.

But while i am deploying statefulset for both mongodb and influxdb with 3 replicas, only one pod (first pod, i.e. mondodb-0 and influxdb-0) is storing the data, non of the remaining pods are cloning the data from the first pod.

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: influxdb
  labels:
    app: influxdb
spec:
  selector:
    matchLabels:
      app: influxdb
  serviceName: influxdb
  replicas: 3
  template:
    metadata:
      labels:
        app: influxdb
    spec:
      terminationGracePeriodSeconds: 10
      containers:
      - name: influxdb
        image: influxdb:1.8.10
        command:
                # - influx
                # - --bind_ip_all
        ports:
        - containerPort: 8086
        env:
         - name: INFLUXDB_USERNAME
           valueFrom:
             secretKeyRef:
               name: influxdb-secret
               key: influxdb-username
         - name: INFLUXDB_PASSWORD
           valueFrom:
             secretKeyRef:
               name: influxdb-secret
               key: influxdb-password
        volumeMounts:
        - name: influxdb-volume
          mountPath: /data/db
  volumeClaimTemplates:
  - metadata:
      name: influxdb-volume
    spec:
      accessModes: [ ReadWriteOnce ]
      resources:
        requests:
          storage: 25Gi

I am trying with the above yaml file, but i am unable to clone the data from first pod to the remaining pods. only one pod is getting the data.