Persistent Volumes

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Problem with Volumes

• When working in large setup, using Volumes directly defined inside the pod spec can be challenging to manage
• If the underlying storage changed, all pod definitions needed updates.

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Solution

• Persistent Volumes allows us to centralise and decouple storage configuration from pod specs.

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What is it

• It is a cluster-wide resource that provides abstracted, reusable storage for users.

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Configured with:

Access Modes:

• How the volume can be accessed
  • ‘ReadWriteOnce’ - one node can mount read/write
  • ‘ReadOnlyMany’ - many nodes can mount read-only
  • ‘ReadWriteMany’ - many nodes can mount read/write

Capacity:

• how much storage is available

Storage backend:

• can be local (hostPath) or remote (e.g., NFS, AWS EBS, etc.)

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Example:

apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-vol1
spec:
  capacity:
    storage: 1Gi
  accessModes:
    - ReadWriteOnce
  hostPath:
    path: /data

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Commands

1. create persistent volumes

kubectl create -f pv-definition.yml

2. get persistent volumes

kubectl get pv

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⬅️ Volumes | Persistent Volume Claims ➡️

References

1. https://kubernetes.io/docs/concepts/storage/persistent-volumes/