PersistentVolumes and PersistentVolumeClaims in Kubernetes

Kubernetes offers an abstraction for storage resources through PersistentVolumes (PVs) and PersistentVolumeClaims (PVCs). This lesson provides a comprehensive overview of how these components work together to manage storage in a Kubernetes environment.

Before diving into the implementation, it's essential to understand the following terms:

• PersistentVolume (PV): A piece of storage in the cluster that has been provisioned by an administrator or dynamically provisioned using Storage Classes.
• PersistentVolumeClaim (PVC): A request for storage by a user. It specifies size and access modes.
• Storage Class: Provides a way to describe the “classes” of storage available.

To create a PV, you can define it in a YAML file. Below is an example:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: my-pv
spec:
  capacity:
    storage: 10Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: /data/my-pv
                

Apply the configuration:

kubectl apply -f my-pv.yaml
                

Next, create a PVC to request the storage defined in your PV:

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: my-pvc
spec:
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi
                

Apply the configuration:

kubectl apply -f my-pvc.yaml
                

Once the PVC is created, Kubernetes will attempt to bind it to an available PV that meets its requirements. You can check the status by running:

kubectl get pvc
                

Ensure that the PVC is in the "Bound" state, which indicates successful binding to a PV.

Here are some best practices to consider:

• Use Storage Classes for dynamic provisioning when possible.
• Specify appropriate access modes for your storage needs.
• Regularly monitor the usage of your PVs and PVCs.
• Clean up unused PVs and PVCs to avoid resource wastage.