Storage Classes¶

StorageClasses provide dynamic provisioning of persistent volumes in Kubernetes.

StorageClass Overview¶

┌────────────────────────────────────────────────┐
│      Dynamic Provisioning Flow                │
├────────────────────────────────────────────────┤
│                                                │
│  User Creates PVC                              │
│         ↓                                      │
│  StorageClass Provisions PV                    │
│         ↓                                      │
│  PVC Binds to PV                              │
│         ↓                                      │
│  Pod Uses PVC                                  │
│                                                │
└────────────────────────────────────────────────┘

Basic StorageClass¶

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: standard
provisioner: kubernetes.io/aws-ebs
parameters:
  type: gp3
  iops: "3000"
  throughput: "125"
reclaimPolicy: Delete
allowVolumeExpansion: true
volumeBindingMode: WaitForFirstConsumer

Cloud Provider StorageClasses¶

AWS EBS¶

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: aws-ebs-gp3
provisioner: ebs.csi.aws.com
parameters:
  type: gp3
  iops: "3000"
  throughput: "125"
  encrypted: "true"
  kmsKeyId: "arn:aws:kms:us-east-1:123456789:key/..."
allowVolumeExpansion: true
volumeBindingMode: WaitForFirstConsumer

GCP Persistent Disk¶

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: gcp-pd-ssd
provisioner: pd.csi.storage.gke.io
parameters:
  type: pd-ssd
  replication-type: regional-pd
allowVolumeExpansion: true
volumeBindingMode: WaitForFirstConsumer

Azure Disk¶

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: azure-disk-premium
provisioner: disk.csi.azure.com
parameters:
  storageaccounttype: Premium_LRS
  kind: Managed
  cachingmode: ReadOnly
allowVolumeExpansion: true
volumeBindingMode: WaitForFirstConsumer

Volume Binding Modes¶

WaitForFirstConsumer¶

volumeBindingMode: WaitForFirstConsumer

Benefits: - Delays provisioning until pod is scheduled - Ensures volume in same zone as pod - Prevents cross-zone mounting issues

Immediate¶

volumeBindingMode: Immediate

Behavior: - Provisions volume immediately - May cause scheduling issues - Use for pre-provisioned volumes

Common Provisioners¶

CSI Drivers¶

# AWS EBS CSI
provisioner: ebs.csi.aws.com

# GCP PD CSI
provisioner: pd.csi.storage.gke.io

# Azure Disk CSI
provisioner: disk.csi.azure.com

# NFS CSI
provisioner: nfs.csi.k8s.io

StorageClass Examples¶

Fast SSD Storage¶

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast-ssd
  annotations:
    storageclass.kubernetes.io/is-default-class: "false"
provisioner: ebs.csi.aws.com
parameters:
  type: io2
  iops: "10000"
  encrypted: "true"
reclaimPolicy: Retain
allowVolumeExpansion: true
volumeBindingMode: WaitForFirstConsumer

Standard HDD Storage¶

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: standard-hdd
provisioner: ebs.csi.aws.com
parameters:
  type: st1
  encrypted: "true"
reclaimPolicy: Delete
allowVolumeExpansion: true
volumeBindingMode: WaitForFirstConsumer

Using StorageClass¶

In PVC¶

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

Default StorageClass¶

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: standard
  annotations:
    storageclass.kubernetes.io/is-default-class: "true"
provisioner: kubernetes.io/aws-ebs
parameters:
  type: gp3

Commands¶

# List storage classes
kubectl get storageclass
kubectl get sc

# Describe storage class
kubectl describe sc standard

# Get default storage class
kubectl get sc -o jsonpath='{.items[?(@.metadata.annotations.storageclass\.kubernetes\.io/is-default-class=="true")].metadata.name}'

# Set default storage class
kubectl patch storageclass standard -p '{"metadata": {"annotations":{"storageclass.kubernetes.io/is-default-class":"true"}}}'

# Create storage class
kubectl apply -f storageclass.yaml

# Delete storage class
kubectl delete sc standard

Best Practices¶

Use CSI Drivers
Enable Volume Expansion
Use WaitForFirstConsumer
Set Appropriate Reclaim Policy
Enable Encryption
Document Storage Classes