we are trying to monitor K8S with Grafana and Prometheus Operator
most of the metrics are working as expected and I was able to see the dashboard with the right value, our system contain 10 nodes with overall 500 pods, now when I restart Prometheus all the data was deleted (I want it to be stored for two week) My question is, How can I define to Prometheus volume to keep the data for two weeks or 100GB DB. I found the following (we user Prometheus operator )

https://github.com/coreos/prometheus-operator/blob/master/Documentation/user-guides/storage.md

This is the config of the Prometheus Operator

apiVersion: apps/v1beta2
kind: Deployment
metadata:
  labels:
    k8s-app: prometheus-operator
  name: prometheus-operator
  namespace: monitoring
spec:
  replicas: 1
  selector:
    matchLabels:
      k8s-app: prometheus-operator
  template:
    metadata:
      labels:
        k8s-app: prometheus-operator
    spec:
      containers:
      - args:
        - --kubelet-service=kube-system/kubelet
        - --logtostderr=true
        - --config-reloader-image=quay.io/coreos/configmap-reload:v0.0.1
        - --prometheus-config-reloader=quay.io/coreos/prometheus-config-reloader:v0.29.0
        image: quay.io/coreos/prometheus-operator:v0.29.0
        name: prometheus-operator
        ports:
        - containerPort: 8080
          name: http

This is the config of the Prometheus

    apiVersion: monitoring.coreos.com/v1
    kind: Prometheus
    metadata:
      name: prometheus
      namespace: monitoring
      labels: 
        prometheus: prometheus
    spec:
      replica: 2
      serviceAccountName: prometheus
      serviceMonitorNamespaceSelector: {}
      serviceMonitorSelector:
        matchLabels:
          role: observeable
      tolerations:
      - key: "WorkGroup"
        operator: "Equal"
        value: "operator"
        effect: "NoSchedule"
      - key: "WorkGroup"
        operator: "Equal"
        value: "operator"
        effect: "NoExecute"
      resources:
        limits:
          cpu: 8000m
          memory: 24000Mi
        requests:
          cpu: 6000m
          memory: 6000Mi
     storage:
       volumeClaimTemplate:
         spec:
        selector:
          matchLabels:
            app: prometheus
        resources:
          requests:
            storage: 100Gi

https://github.com/coreos/prometheus-operator/blob/master/Documentation/user-guides/storage.md

we have file system (nfs), and the above storage config doesn't works, my question are:

1. what I miss here is how to config the volume, server , path in the following its under the nfs section

where should I find this "/path/to/prom/db" ? how can I refer to it? should I create it somehow, or just provide the path. we have nfs configured in our system

2. how to combine it to Prometheus

As I dont have deep knowlage in pvc and pv I've created the following( not sure regard those values, what is my server and what path should I provide...

server: myServer
path: "/path/to/prom/db"

what should I put there and how I make my Prometheus (i.e. the config I have provided in the question )to use it

apiVersion: v1
kind: PersistentVolume
metadata:
  name: prometheus
  namespace: monitoring
  labels:
    app: prometheus
    prometheus: prometheus
spec:
  capacity:
    storage: 100Gi
  accessModes:
    - ReadWriteOnce # required
  nfs:
    server: myServer
    path: "/path/to/prom/db"

if there any other persistence volume other than nfs which I can use for my use-case please advice how