Understanding Kubernetes: Part 12 -Persistent Volume Claim (PVC)

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Last updated 4 months ago

Understanding Kubernetes: Part 12 -Persistent Volume Claim (PVC)

If you’ve been following our Kubernetes series 2025, welcome back! For new readers, check out Part 11: Persistent Volume

What is a Persistent Volume Claim (PVC) in Kubernetes?

A Persistent Volume Claim (PVC) in Kubernetes is a request for storage by a user. It acts as a bridge between pods and Persistent Volumes (PVs), allowing pods to use storage without knowing the details of the underlying infrastructure. A PVC specifies the amount of storage and access modes needed, and Kubernetes binds it to a suitable PV.

For example:

If you have a web application like WordPress that needs persistent storage for its data, a PVC can request 10Gi of storage with a ReadWriteOnce access mode. Kubernetes will then bind the PVC to an appropriate PV, ensuring the application has durable and reliable storage.

Persistent Volume Claim Capabilities:

Dynamic Binding: Automatically provisions storage if a StorageClass is configured.
Flexibility: Allows users to specify size, access modes, and storage class without managing the PV directly.
Pod Integration: PVCs can be mounted as volumes in pods, making storage accessible seamlessly.
Decoupling: Separates storage requests from storage implementation, supporting portability and scalability.

In my previous role:

As a Senior DevOps Engineer, I used PVCs extensively for stateful applications like PostgreSQL. For one project, we deployed a PostgreSQL database that required 20Gi of storage. I created a PVC to request this storage, which was dynamically provisioned using an AWS EBS-backed StorageClass. By mounting the PVC to the PostgreSQL pod, we ensured data persistence across pod restarts and node failures. This setup played a critical role in maintaining data integrity and application uptime.

Here’s a simple YAML for a Persistent Volume Claim:

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

This PVC requests 10Gi of storage with a ReadWriteOnce access mode. When bound to a matching PV, it provides the requested storage, which can then be used by pods for persistent data storage. PVCs are essential for dynamically managing storage in Kubernetes, enabling a seamless and scalable approach to persistent workloads.

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