Volumes vs Persistent Volumes in Kubernetes - Hands-On Comparison

Understanding Volumes vs Persistent Volumes in Kubernetes

📖 Scenario: You are working on a Kubernetes cluster where you need to store data generated by your applications. You want to understand the difference between simple Volumes and Persistent Volumes (PV) to manage data storage effectively.

🎯 Goal: Build a simple Kubernetes setup that defines a Pod using a basic Volume and then extend it to use a Persistent Volume and Persistent Volume Claim (PVC). This will help you see how data storage works in Kubernetes and the difference between ephemeral and persistent storage.

📋 What You'll Learn

Create a Pod manifest with an emptyDir Volume

Add a Persistent Volume manifest with specific storage capacity

Create a Persistent Volume Claim manifest to request storage

Modify the Pod manifest to use the Persistent Volume Claim

Print the Pod specification to verify the volume configuration

💡 Why This Matters

🌍 Real World

In real Kubernetes clusters, applications often need to store data that outlives the Pod lifecycle. Understanding Volumes and Persistent Volumes helps manage data persistence and sharing.

💼 Career

DevOps engineers and Kubernetes administrators must know how to configure storage correctly to ensure application data durability and availability.

1

Create a Pod with an emptyDir Volume

Create a Kubernetes Pod manifest named pod.yaml with a Pod called my-pod. Inside the Pod spec, add a container named app-container using the image nginx. Add a Volume named temp-storage of type emptyDir. Mount this volume inside the container at /usr/share/nginx/html.

Kubernetes

# Write the Pod manifest with emptyDir volume here

Need a hint?

Use emptyDir: {} under volumes to create a temporary storage volume.

2

Define a Persistent Volume with storage capacity

Create a Persistent Volume manifest named pv.yaml with kind PersistentVolume. Name it pv-storage. Set the storage capacity to 1Gi under spec.capacity.storage. Use hostPath with path /mnt/data as the volume source. Set the access mode to ReadWriteOnce.

Kubernetes

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - name: app-container
    image: nginx
    volumeMounts:
    - mountPath: /usr/share/nginx/html
      name: temp-storage
  volumes:
  - name: temp-storage
    emptyDir: {}

# Now create a PersistentVolume manifest named pv-storage below
# Your code here

Need a hint?

Use hostPath to simulate persistent storage on the node.

3

Create a Persistent Volume Claim and update Pod to use it

Create a Persistent Volume Claim manifest named pvc.yaml with kind PersistentVolumeClaim. Name it pvc-storage. Request 1Gi storage with access mode ReadWriteOnce. Then, update the Pod manifest to remove the emptyDir volume and instead use a volume named persistent-storage that references the claim pvc-storage. Mount this volume inside the container at /usr/share/nginx/html.

Kubernetes

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - name: app-container
    image: nginx
    volumeMounts:
    - mountPath: /usr/share/nginx/html
      name: temp-storage
  volumes:
  - name: temp-storage
    emptyDir: {}
---
apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-storage
spec:
  capacity:
    storage: 1Gi
  accessModes:
  - ReadWriteOnce
  hostPath:
    path: /mnt/data

# Now create a PersistentVolumeClaim named pvc-storage
# Then update the Pod to use persistent-storage volume referencing pvc-storage
# Your code here

Need a hint?

Use persistentVolumeClaim.claimName in the Pod volume to link the PVC.

4

Print the final Pod manifest to verify volume usage

Print the complete Pod manifest named my-pod to verify it uses the Persistent Volume Claim volume named persistent-storage mounted at /usr/share/nginx/html.

Kubernetes

apiVersion: v1
kind: Pod
metadata:
  name: my-pod
spec:
  containers:
  - name: app-container
    image: nginx
    volumeMounts:
    - mountPath: /usr/share/nginx/html
      name: persistent-storage
  volumes:
  - name: persistent-storage
    persistentVolumeClaim:
      claimName: pvc-storage

# Print the Pod manifest below
# Your code here

Need a hint?

Use kubectl get pod my-pod -o yaml to print the Pod manifest.