Bits of .NET

💾 Pods Are Ephemeral. Data Shouldn’t Be.

Pod restarts lose data. Persistent Volumes (PV) store data outside pods. Databases, uploads, logs survive restarts.

📝 Persistent Volume Claim

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

---
apiVersion: v1
kind: Pod
metadata:
  name: postgres
spec:
  containers:
  - name: postgres
    image: postgres:15
    volumeMounts:
    - name: postgres-storage
      mountPath: /var/lib/postgresql/data
  volumes:
  - name: postgres-storage
    persistentVolumeClaim:
      claimName: postgres-pvc

🎯 Access Modes

ReadWriteOnce (RWO):
- Read and write from single node
- Most common for databases

ReadOnlyMany (ROX):
- Read-only from multiple nodes
- For shared config, static assets

ReadWriteMany (RWX):
- Read and write from multiple nodes
- For shared file systems, media uploads

ReadWriteOncePod (RWOP):
- Read and write from single pod

💡 Commands

• kubectl get pv (Persistent Volumes)
• kubectl get pvc (Persistent Volume Claims)
• kubectl describe pvc postgres-pvc
• Storage classes: AWS EBS, Azure Disk, GCP PD, NFS
• Dynamic provisioning (storage class creates PV automatically)