What are Storage Classes and CSI Drivers in Kubernetes?

Question

Accepted Answer

**Storage Classes** — define storage type. **CSI Drivers** — connection plugins.

**Storage Classes:**
```yaml
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: fast-ssd
provisioner: ebs.csi.aws.com
parameters:
  type: gp3
  fsType: ext4
reclaimPolicy: Delete
allowVolumeExpansion: true
volumeBindingMode: WaitForFirstConsumer
---
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: standard
provisioner: ebs.csi.aws.com
parameters:
  type: gp2
reclaimPolicy: Retain
```

**PVC:**
```yaml
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: data-pvc
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: fast-ssd
  resources:
    requests:
      storage: 50Gi
```

**Popular CSI:** aws-ebs-csi, gcp-pd-csi, disk.csi.azure.com, nfs-subdir-external-provisioner, longhorn, rook-ceph.

**reclaimPolicy:** Delete (deleted when PVC is removed), Retain (preserved).

**volumeBindingMode:** Immediate, WaitForFirstConsumer (zone-aware).

**Verification:** `kubectl get storageclass`, `kubectl get pv`, `kubectl get pvc`.

DevOps: What are Storage Classes and CSI Drivers in Kubernetes?