pv-pvc.md

Persistent Volume

Phase

• A volume will be in one of the following phases:

  • Available -- a free resource that is not yet bound to a claim
  • Bound -- the volume is bound to a claim
  • Released -- the claim has been deleted, but the resource is not yet reclaimed by the cluster
  • Failed -- the volume has failed its automatic reclamation

• Persistent Volume ON NFS

apiVersion: v1
kind: PersistentVolume
metadata:
  name: pv-name
spec:
  capacity:
    storage: 5Gi
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  persistentVolumeReclaimPolicy: Recycle
  storageClassName: slow
  mountOptions:
    - hard
    - nfsvers=4.0
  nfs:
    path: /dir/path/on/nfs/server
    server: nfs-server-ip-address

• Persistent Volume on Google Cloud

apiVersion: v1
kind: PersistentVolume
metadata:
  name: test-volume
  labels:
    failure-domain.beta.kuberentes.io/zone: us-central1-a__us_central1-b
spec:
  capacity:
    storage: 400Gi
  accessModes:
  - ReadWriteOnce
  gcePersistentDisk:
    pdName: my-data-disk
    fsType: ext4

• Depending on storage type, spec attributes differ

Persistent Volume claim

• Application has to claim the Persistent volume

kind: PersistentVolumeClaim
apiVersion: v1
metadata: 
  name: pvc-name
spec:
  storageClassName: manual
  volumeMode: Filesystem
  accessModes:
    - ReadWriteOnce
  resources:
    requests:
      storage: 10Gi

• Use that PVC in Pods configuration

apiVersion: v1
kind: Pod
metadata:
  name: mypod
spec:
  containers:    ## Where to mount volume in the container
    - name: myfrontend
      image: nginx
      volumeMounts: 
      - mountPath: "/var/www/html"
      name: mypd
  volume:   ## What volume to provide
    - name: mypd
      persistentVolumeClaim:
        claimName: pvc-name

Refrences

• Kubernetes Volume Basics: emptyDir and PersistentVolume

• Kubernetes: Persistent Volume For Beginners:

• Persistent Volume Claim for StatefulSet

• Kubernetes Storage 101

• Configuring Persistent Storage