Problem deploying postgres in local minikube single-node cluster

Question

I am new to kubernetes. To learn more about kubernetes, I am trying to deploy backstage to a 9-node Pi kubernetes cluster I deployed with ansible. I am following this article https://backstage.io/docs/deployment/k8s/

To prepare, i am trying to deploy first to a minikube single-node cluster on my Apple laptop.

As have many others, I am getting an error in deploying my postgres container with "Error: stat /mnt/data: no such file or directory"

That directory exists on my laptop and, though I don't want to, I set it to 777 since I am not certain under what context minikube is running.

Some have suggested that is misleading message; that said, it's my undertanding (which no one has clearly specified that i have seen) that the postgres database that would reside in /var/lib/postgresql/data would be persisted in /mnt/data on my laptop. Is that true?

Here are my deployment scripts:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: postgres-storage
  namespace: classicrock
  labels:
    type: local
spec:
  storageClassName: manual
  capacity:
    storage: 2G
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Retain
  hostPath:
    path: '/mnt/data'
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: postgres-storage-claim
  namespace: classicrock
spec:
  storageClassName: manual
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 2G
  volumeName: postgres-storage

and

apiVersion: apps/v1
kind: Deployment
metadata:
  name: postgres
  namespace: classicrock
spec:
  replicas: 1
  selector:
    matchLabels:
      app: postgres
  template:
    metadata:
      labels:
        app: postgres
    spec:
      containers:
        - name: postgres
          image: postgres:17.4-alpine
          imagePullPolicy: 'IfNotPresent'
          ports:
            - containerPort: 5432
          envFrom:
            - secretRef:
                name: postgres-secrets
          env:
            - name: POSTGRES_HOST
              value: postgres.classicrock
            - name: POSTGRES_PORT
              value: '5432'
          volumeMounts:
            - mountPath: /var/lib/postgresql/data
              name: postgresdb
              subPath: data
      volumes:
        - name: postgresdb
          persistentVolumeClaim:
            claimName: postgres-storage-claim