Storage

Concepts

Resource	Role
PersistentVolume (PV)	Cluster-level storage resource
PersistentVolumeClaim (PVC)	Namespaced request for storage
StorageClass	Template for dynamic provisioning

StorageClass (AWS EBS gp3)

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: gp3
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
provisioner: ebs.csi.aws.com
parameters:
  type: gp3
  iops: "3000"
  throughput: "125"
  encrypted: "true"
volumeBindingMode: WaitForFirstConsumer
reclaimPolicy: Retain
allowVolumeExpansion: true

PVC

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: postgres-data
  namespace: production
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: gp3
  resources:
    requests:
      storage: 50Gi

Access modes

Mode	Abbreviation	Support
ReadWriteOnce	RWO	Most block storage
ReadWriteMany	RWX	NFS, EFS, CephFS
ReadOnlyMany	ROX	Rare

Volume expansion

Most CSI drivers support online expansion — no pod restart needed.

kubectl patch pvc postgres-data \
  -n production \
  -p '{"spec":{"resources":{"requests":{"storage":"100Gi"}}}}'

Ephemeral storage

For scratch space that doesn't need persistence, use emptyDir:

volumes:
  - name: cache
    emptyDir:
      sizeLimit: 500Mi

Data loss

emptyDir is destroyed when the pod is removed. Never store anything you need to keep.