Demo Storage Classes in Action

Every application that stores data needs storage. In Kubernetes, workloads request storage through StorageClasses, which define how PersistentVolumes (PVs) are provisioned and managed. Think of a StorageClass as the platform’s storage menu: fast SSD-backed volumes for databases, cost-effective spinning disks for archives, cloud block storage provisioned on demand, or replicated volumes for production workloads. Teams pick what they need and Kubernetes handles provisioning.

A presentation slide showing "Demo" on the left and a large blue curved shape on the right with the title "Storage Classes in Action." A small "© Copyright KodeKloud" appears in the bottom-left corner.

This guide walks through:

Listing StorageClasses
Inspecting important StorageClass fields
Creating PVCs that request specific StorageClasses
Attaching Pods to those PVCs
Observing how reclaim policies affect the PV lifecycle

References:

1 — List StorageClasses

To list StorageClasses available in the cluster:

kubectl get sc

Sample output:

NAME                          PROVISIONER             RECLAIMPOLICY  VOLUMEBINDINGMODE       ALLOWVOLUMEEXPANSION  AGE
archive                       rancher.io/local-path   Retain         WaitForFirstConsumer    false                 16m
fast                          rancher.io/local-path   Delete         WaitForFirstConsumer    false                 16m
local-path (default)          rancher.io/local-path   Delete         WaitForFirstConsumer    false                 16m

Note the (default) annotation on local-path. If a PVC does not explicitly request a storageClassName, it will be provisioned using the default StorageClass.

2 — Inspect a StorageClass (example: fast)

Describe the fast StorageClass to view its key fields:

kubectl describe storageclass fast

Example (trimmed) output:

Name:                fast
IsDefaultClass:      No
Provisioner:         rancher.io/local-path
ReclaimPolicy:       Delete
VolumeBindingMode:   WaitForFirstConsumer
AllowVolumeExpansion: <unset>
Parameters:          <none>
MountOptions:        <none>
Events:              <none>

Key fields explained:

Field	Purpose
`Provisioner`	The plugin that provisions volumes (e.g., cloud provider, local-path).
`ReclaimPolicy`	What happens to the PV after its PVC is deleted (`Delete`, `Retain`).
`VolumeBindingMode`	When binding/provisioning occurs (`Immediate` vs `WaitForFirstConsumer`).
`AllowVolumeExpansion`	Whether the volume can be expanded after creation.

Reclaim policy and volume binding behavior are crucial for correctness and cost control:

ReclaimPolicy	Behavior	Use case
`Delete`	Underlying PV and storage resource are removed when PVC is deleted.	Ephemeral workloads, autoscaled test environments.
`Retain`	PV remains and moves to `Released` state; data remains on the volume. Administrator action required to reuse or delete.	Databases or critical workloads where preserving data is required.

VolumeBindingMode	Behavior	Benefit
`Immediate`	PV is provisioned/bound as soon as PVC is created.	Simple — but can provision in wrong zone for scheduled Pod.
`WaitForFirstConsumer`	Provisioning/binding waits until a Pod using the PVC is scheduled.	Avoids cross-zone or wrong-node provisioning; ensures local affinity.

3 — Create a PVC using the `fast` StorageClass

This PVC requests 1Gi and specifies storageClassName: fast:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: app-storage
  namespace: storage
spec:
  accessModes:
  - ReadWriteOnce
  storageClassName: fast
  resources:
    requests:
      storage: 1Gi

Apply it:

kubectl apply -f pvc-fast.yaml

Because the fast StorageClass uses WaitForFirstConsumer, the PVC will remain in Pending until a Pod that mounts it is scheduled:

kubectl get pvc -n storage

Example (Pending):

NAME          STATUS    VOLUME   CAPACITY   ACCESS MODES   STORAGECLASS   AGE
app-storage   Pending   <none>   <unset>    <none>         fast           25s

4 — Attach a Pod to the PVC

Create a Pod manifest that mounts the PVC:

apiVersion: v1
kind: Pod
metadata:
  name: app
  namespace: storage
spec:
  containers:
  - name: app
    image: nginx
    volumeMounts:
    - mountPath: /data
      name: storage
  volumes:
  - name: storage
    persistentVolumeClaim:
      claimName: app-storage

Apply the Pod:

kubectl apply -f pod-app.yaml

Watch the PVC transition from Pending to Bound:

kubectl get pvc -n storage -w

Sample transition (trimmed):

app-storage   Pending                                   fast
app-storage   Pending   pvc-1dcc29bc-a8a1-4c97-a5f9-bb0e19dadcd7   0   fast
app-storage   Bound     pvc-1dcc29bc-a8a1-4c97-a5f9-bb0e19dadcd7   1Gi  RWO  fast

A PV is dynamically provisioned and bound to the PVC. Verify the PV:

kubectl get pv

Example PV output:

NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM
pvc-1dcc29bc-a8a1-4c97-a5f9-bb0e19dadcd7   1Gi        RWO            Delete           Bound    storage/app-storage

5 — Demonstrate a `Retain` reclaim policy (archive)

Inspect the archive StorageClass:

kubectl describe storageclass archive

Example (trimmed):

Name:                archive
IsDefaultClass:      No
Provisioner:         rancher.io/local-path
ReclaimPolicy:       Retain
VolumeBindingMode:   WaitForFirstConsumer

Create a PVC that uses archive (500Mi):

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: archive-storage
  namespace: storage
spec:
  accessModes:
  - ReadWriteOnce
  storageClassName: archive
  resources:
    requests:
      storage: 500Mi

Apply the PVC and attach a Pod (Pod manifest similar to the previous one, using claimName: archive-storage). After creating the Pod, the PVC becomes Bound and a PV appears. Check PVCs and PVs:

kubectl get pvc -n storage
kubectl get pv

Example outputs showing both PVs:

# PVCs
NAME             STATUS   VOLUME                                     CAPACITY   ACCESS MODES   STORAGECLASS
app-storage      Bound    pvc-1dcc29bc-a8a1-4c97-a5f9-bb0e19dadcd7   1Gi        RWO            fast
archive-storage  Bound    pvc-ad21aa2d-5f95-4ec7-8f61-bfa1774d10d6   500Mi      RWO            archive

# PVs
NAME                                       CAPACITY   ACCESS MODES   RECLAIM POLICY   STATUS   CLAIM
pvc-1dcc29bc-a8a1-4c97-a5f9-bb0e19dadcd7   1Gi        RWO            Delete           Bound    storage/app-storage
pvc-ad21aa2d-5f95-4ec7-8f61-bfa1774d10d6   500Mi      RWO            Retain           Bound    storage/archive-storage

Now delete the PVC that used the Retain StorageClass:

kubectl delete pvc -n storage archive-storage

Because the reclaim policy is Retain, the PV is not deleted. Instead, it transitions to Released after the binding is removed. Watch the PV:

kubectl get pv -w

Example PV state change:

pvc-ad21aa2d-5f95-4ec7-8f61-bfa1774d10d6   500Mi   RWO   Retain   Bound     storage/archive-storage
pvc-ad21aa2d-5f95-4ec7-8f61-bfa1774d10d6   500Mi   RWO   Retain   Released  <none>

When a PV is Released, the underlying data remains on the volume. An administrator must manually inspect, scrub, or reclaim that volume before it can be reused.

6 — Quick reference and recommendations

Quick commands:

Task	Command
List StorageClasses	`kubectl get sc`
Describe StorageClass	`kubectl describe storageclass <name>`
Create PVC	`kubectl apply -f pvc.yaml`
Create Pod	`kubectl apply -f pod.yaml`
Watch PVCs	`kubectl get pvc -n <ns> -w`
Watch PVs	`kubectl get pv -w`

Best practices when choosing a StorageClass:

Use Retain for stateful workloads where you must preserve data (databases, critical workloads).
Use Delete for ephemeral workloads that should be cleaned up automatically.
Prefer WaitForFirstConsumer in multi-zone clusters to avoid provisioning volumes in the wrong zone.
Choose the right access mode: ReadWriteOnce (RWO), ReadWriteMany (RWX) depending on application needs.
Verify AllowVolumeExpansion when you expect to grow volumes after initial provisioning.

When preparing for an exam or designing a cluster, always list your StorageClasses and inspect their reclaimPolicy and volumeBindingMode. These fields determine if storage is provisioned immediately or later, where it will be provisioned, and what happens to the backing storage when a PVC is deleted.

Course Introduction

Platform Architecture and Infrastructure

GitOps and Continuous Delivery

Platform APIs and Self-Service Capabilities

Observability and Operations

Security and Policy Enforcement

Conclusion

Demo Storage Classes in Action

1 — List StorageClasses

2 — Inspect a StorageClass (example: fast)

3 — Create a PVC using the `fast` StorageClass

4 — Attach a Pod to the PVC

5 — Demonstrate a `Retain` reclaim policy (archive)

6 — Quick reference and recommendations

Watch Video

Practice Lab

​1 — List StorageClasses

​2 — Inspect a StorageClass (example: fast)

​3 — Create a PVC using the fast StorageClass

​4 — Attach a Pod to the PVC

​5 — Demonstrate a Retain reclaim policy (archive)

​6 — Quick reference and recommendations

Watch Video

Practice Lab

1 — List StorageClasses

2 — Inspect a StorageClass (example: fast)

3 — Create a PVC using the `fast` StorageClass

4 — Attach a Pod to the PVC

5 — Demonstrate a `Retain` reclaim policy (archive)

6 — Quick reference and recommendations