<p>Ive created and volume and mount it (for the first time ) to my application. I’ve postgres db 
which I want to keep the data with a volume if the container done some restart/stop/killed etc </p>

<p>when I deploy my app using <code>helm</code> I see the following</p>

<pre><code>Name:          feature
Namespace:     un
StorageClass:  default
Status:        Bound
Volume:        pvc-7f0-25d2-4-90c1-541f5d262
Labels:        app=un
               chart=un-0.0.1
               heritage=Tiller
               release=elder-fox
Annotations:   pv.kubernetes.io/bind-completed: yes
               pv.kubernetes.io/bound-by-controller: yes
               volume.beta.kubernetes.io/storage-provisioner: kubernetes.io/aws-ebs
Finalizers:    [kubernetes.io/pvc-protection]
Capacity:      11Gi
Access Modes:  RWO
VolumeMode:    Filesystem
Events:
  Type       Reason                 Age   From                         Message
  ----       ------                 ----  ----                         -------
  Normal     ProvisioningSucceeded  102m  persistentvolume-controller  Successfully provisioned volume  pvc-7f0-25d2-4-90c1-541f5d262
  using kubernetes.io/aws-ebs
Mounted By:  fe-postgres-9f8c7-49w26


</code></pre>

<p>My question is how <strong>can I verify</strong> that the data which I enter to the db is actually mapped to
a volume and kept there, I see that the volume is bound but not sure if it really keep the data from the postgress db  ?</p>

<p>This is the object I’ve been created</p>

<p><code>PersistentVolumeClaim</code></p>

<pre><code>{{- if (and .Values.persistence.enabled (eq .Values.persistence.existingClaim "")) }}
kind: PersistentVolumeClaim
apiVersion: v1
metadata:
  name: {{ template "un.fullname" . }}
  namespace: {{ .Values.namespace }}
  labels:
    app: {{ template "un.name" . }}
    chart: {{ .Chart.Name }}-{{ .Chart.Version }}
    release: {{ .Release.Name }}
    heritage: {{ .Release.Service }}
spec:
  accessModes:
    - {{ .Values.persistence.accessMode }}
  resources:
    requests:
      storage: {{ .Values.persistence.size }}
{{- if .Values.persistence.storageClass }}
{{- if (eq "-" .Values.persistence.storageClass) }}
  storageClassName: ''
{{- else }}
  storageClassName: {{ .Values.persistence.storageClass }}
{{- end }}
{{- end }}
{{- end }}

</code></pre>

<p>postgress </p>

<pre><code>{{- if .Values.config.postgres.internal }}
apiVersion: v1
kind: Service
metadata:
  name: {{ template "un.fullname" . }}-postgres
  namespace: {{ .Values.namespace }}
  labels:
    app: {{ template "un.name" . }}-postgres
    chart: {{ .Chart.Name }}-{{ .Chart.Version }}
    release: {{ .Release.Name }}
    heritage: {{ .Release.Service }}
spec:
  type: ClusterIP
  ports:
    - name: postgres
      port: 5432
      targetPort: container
  selector:
    app: {{ template "un.name" . }}-postgres
    release: {{ .Release.Name }}
{{- end }}
</code></pre>

<p>This is the deployment </p>

<pre><code>{{- if .Values.config.postgres.internal }}
apiVersion: apps/v1beta1
kind: Deployment
metadata:
  name: {{ template "un.fullname" . }}-postgres
  namespace: {{ .Values.namespace }}
  labels:
    app: {{ template "un.name" . }}-postgres
    chart: {{ .Chart.Name }}-{{ .Chart.Version }}
    release: {{ .Release.Name }}
    heritage: {{ .Release.Service }}
spec:
  template:
    metadata:
      labels:
        app: {{ template "un.name" . }}-postgres
        release: {{ .Release.Name }}
    spec:
      containers:
        - name: {{ template "un.fullname" . }}-postgres
          image: {{ .Values.images.postgres.repository }}:{{ .Values.images.postgres.tag }}
          imagePullPolicy: {{ .Values.images.postgres.pullPolicy }}
          ports:
            - name: container
              containerPort: 5432
          volumeMounts:
            - name: data
              mountPath: /var/lib/postgresql/data
              subPath: postgres
          env:
            - name: POSTGRES_DB
              valueFrom:
                configMapKeyRef:
                  name: {{ template "un.fullname" . }}
                  key: postgres_database
            - name: POSTGRES_PASSWORD
              valueFrom:
                secretKeyRef:
                  name: {{ template "un.fullname" . }}
                  key: postgres_password
          livenessProbe:
            tcpSocket:
              port: container
{{ toYaml .Values.probes.liveness | indent 12 }}
          readinessProbe:
            tcpSocket:
              port: container
{{ toYaml .Values.probes.readiness | indent 12 }}
      volumes:
        - name: data
          {{- if .Values.persistence.enabled }}
          persistentVolumeClaim:
            claimName: {{ .Values.persistence.existingClaim | default (include "un.fullname" . ) }}
          {{- else }}
          emptyDir: {}
          {{- end }}
{{- end }}

</code></pre>

<p>This is the values yaml</p>

<pre><code>images:
  postgres:
    repository: postgres
    tag: 10
    pullPolicy: IfNotPresent

config:
  postgres:
    database: un
    host: ''
    internal: true
    password: postgres
    port: 5432
    url: ''
    username: postgres
…

</code></pre>

<p>I don't see persistence.enabled is set in your value file so I assume that you are using emptyDir as volume(<code>kubectl get deployment &lt;your deployment name&gt; -o yaml</code> will give you the running status of your deployment). emptyDir has the same lifecycle as the Pod, which means if the Pod is removed from a node for any reason, the data in the emptyDir is deleted forever(Please note that container crashing does NOT remove a Pod from a Node, so the data in an emptyDir volume is safe across Container crashes). </p>

<p>If you want to keep data persisted even after Pod is removed, you need to set persistence.enabled to true in your value file and specify a storageclass(or you have a default storageclass defined. Running <code>kubectl get storageclasses</code> to figure it out)</p>

<p>You can verify that whether the data is persisted by deleting the postgres Pods(Deployment will recreate one after Pod removal)</p>
