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Binding a Pod to a USB Drive on a Specific Node

The goal is for a Pod to use a USB hard drive physically attached to a specific Node (e.g., a worker node), the best practice is:

TechnologyPurpose
nodeSelector (or nodeAffinity)Pin the Pod to the Node with the attached USB
hostPath volumeMount the USB drive’s path on the Node (e.g., /mnt/nas-backup) directly into the Pod

🛡️ Advantages

  • Simple to implement and quick to deploy
  • No need for extra NFS or distributed storage setup
  • Full control over which physical disk the data lands on
  • Data persists on the host; Pod crashes or restarts won't cause data loss

⚠️ Caveats

  • The USB drive can only be accessed by Pods scheduled on that specific Node — no cross-node sharing
  • Scheduling the Pod on other Nodes will cause volume mount failures or Pod crashes
  • Make sure the USB drive is automatically mounted on the Node before Pod creation

🚧 Getting Started​

🏁 Create a Dummy Local Volume on the Worker Node​

On the worker Node (e.g., rpi4-argon), run:

sudo mkdir -p /tmp/mock-usb
sudo chmod 777 /tmp/mock-usb  # relaxed permissions for testing ease

🧪 BusyBox Test Pod (Mounting the mock USB with hostPath)​

# ./config/busybox-local-vol-pod.yaml
apiVersion: v1
kind: Pod
metadata:
  name: busybox-local-volume
spec:
  nodeSelector:
    kubernetes.io/hostname: rpi4-argon
  containers:
    - name: busybox
      image: busybox
      command: ['sh', '-c', 'echo hello-world > /data/hello.txt && sleep 3600']
      volumeMounts:
        - mountPath: /data
          name: local-volume
  volumes:
    - name: local-volume
      hostPath:
        path: /tmp/mock-usb
        type: Directory

Steps​

  1. Apply the Pod:
kubectl apply -f config
  1. Exec into the Pod:
kubectl exec -it busybox-local-volume -- sh
cat /data/hello.txt
echo '---' >> /data/hello.txt
  1. Check on the worker Node if the file is created:
cat /tmp/mock-usb/hello.txt

If you see:

hello-world
---

it means your hostPath volume is successfully mounted 🎉!

🧼 Cleanup​

kubectl delete pod busybox-local-volume
rm /tmp/mock-usb/hello.txt