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Summary

Storage and Volumes

Learn how storage works in Kubernetes, how to use persistent volumes in K3s, and set up storage that survives pod restarts.

By Kevin McAleer,    3 Minutes

Page last updated May 24, 2025

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In Kubernetes, storage isn’t tied to a container like in Docker — it’s managed independently as persistent volumes (PVs) and persistent volume claims (PVCs).

This lesson will show you how storage works in K3s, how to use the built-in local-path provisioner, and how to prepare for external storage options (like NFS or USB SSDs).

💾 How Storage Works in K3s

K3s includes a default dynamic storage provisioner called local-path-provisioner.

  • It uses local disk storage on the node running the pod
  • PVCs are automatically provisioned
  • Easy to use, but not shared across nodes

⚠️ If a pod moves to a different node, its data may not follow.

📁 Step 1: Test with a Simple PVC

Create a file pvc-demo.yaml:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: demo-pvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 1Gi

Apply it:

kubectl apply -f pvc-demo.yaml

📦 Step 2: Mount PVC in a Pod

Create a pod with a volume mount:

apiVersion: v1
kind: Pod
metadata:
  name: pvc-tester
spec:
  containers:
    - name: busybox
      image: busybox
      command: [ "sleep", "3600" ]
      volumeMounts:
        - mountPath: "/data"
          name: myvolume
  volumes:
    - name: myvolume
      persistentVolumeClaim:
        claimName: demo-pvc

Apply it:

kubectl apply -f pvc-tester.yaml

Then exec into the pod and test:

kubectl exec -it pvc-tester -- sh
# Inside pod:
echo "Hello Pi Cluster" > /data/test.txt
cat /data/test.txt

🧠 Where Is the Data Stored?

On the node hosting the pod, the data is typically under:

/opt/local-path-provisioner

Each PVC is stored in its own directory.

📤 External Storage Options (Optional)

For more advanced setups:

Option Benefit Tool
USB SSD Fast, local storage Mount manually or with Longhorn
NFS Server Shared across all nodes Use nfs-subdir-external-provisioner
Ceph Highly available block storage More complex to set up

🛠 Consider using Longhorn if you want persistent block storage with replication and snapshots.

🧪 Cleanup

To remove test volumes and pods:

kubectl delete pod pvc-tester
kubectl delete pvc demo-pvc

✅ Summary

You now know how to:

  • Create persistent volume claims in K3s
  • Use local-path provisioner for basic storage needs
  • Mount volumes into pods
  • Plan for external and scalable storage options

Next up: Ingress and Services

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