Bits of .NET

💾 Persistent Volumes = Storage Management

Data outlives pods. Persistent Volumes store data. PV, PVC, StorageClass — storage done right.

📝 PV and PVC

# PersistentVolume (PV)
apiVersion: v1
kind: PersistentVolume
metadata:
    name: postgres-pv
spec:
    capacity:
        storage: 10Gi
    volumeMode: Filesystem
    accessModes:
        - ReadWriteOnce
    persistentVolumeReclaimPolicy: Retain
    hostPath:
        path: /data/postgres

# PersistentVolumeClaim (PVC)
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
    name: postgres-pvc
spec:
    accessModes:
        - ReadWriteOnce
    resources:
        requests:
            storage: 10Gi

# Using PVC in Pod
apiVersion: v1
kind: Pod
metadata:
    name: postgres
spec:
    containers:
    - name: postgres
        image: postgres:15
        env:
        - name: POSTGRES_PASSWORD
            value: postgres
        volumeMounts:
        - name: postgres-storage
            mountPath: /var/lib/postgresql/data
    volumes:
    - name: postgres-storage
        persistentVolumeClaim:
            claimName: postgres-pvc

🎯 Storage Classes

# StorageClass
apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
    name: fast-storage
provisioner: kubernetes.io/aws-ebs
parameters:
    type: gp3
    fsType: ext4
reclaimPolicy: Delete
allowVolumeExpansion: true
volumeBindingMode: Immediate

# PVC with StorageClass
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
    name: fast-pvc
spec:
    storageClassName: fast-storage
    accessModes:
        - ReadWriteOnce
    resources:
        requests:
            storage: 20Gi

# Dynamic provisioning
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
    name: dynamic-pvc
spec:
    storageClassName: fast-storage
    accessModes:
        - ReadWriteOnce
    resources:
        requests:
            storage: 10Gi

💡 Storage Tips

• ReadWriteOnce (RWO) → Single node read/write
• ReadOnlyMany (ROX) → Multiple nodes read-only
• ReadWriteMany (RWX) → Multiple nodes read/write
• Use StorageClass for dynamic provisioning
• Plan for data backup