• Previous Lecture –> PV is attached to a PVC, which is itself then attached to a pod definition file.
  • An example of creating a Persistent Volume on Google Cloud: 
    gcloud beta compute disks create
    --size 1GB
    --region us-east1
    pd-disk
  • The accompanying Persistent Volume would be: 
    apiVersion: v1
kind: PersistentVolume
metadata:
 name: pv-vol1
spec:
accessModes:
    - ReadWriteOnce
capacity:
    storage: 500Mi
gcePersistentDisk:
   pdName: pd-disk
   fstype: ext4
  • When an application requires storage, have to manually provision the disk on Google Cloud and then create the PV definition file.
    • This is called Static Provisioning.
  • It is better if the volume is provisioned automatically when the application requires it.
    • This is where Storage Classes help.
  • Can automatically provision storage on Google Cloud.
  • Attach it to pods when a claim is made.
    • This is called Dynamic Provisioning of volumes.
  • It is done by making a Storage Class object: 
    apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
 name: google-storage
provisioner: kubernetes.io/gce-pd
  • Then we do not need the PV definition file, as the Persistent Volume will be created when the Storage Class is generated.
  • For the Persistent Volume Claim, have to add the following storageClassName to the config: ``` apiVersion: v1 kind: PersistentVolumeClaim metadata: name: myclaim spec: accessModes:
    • ReadWriteOnce storageClassName: google-storage resource: requests: storage: 500Mi ```
  • The pod definition does not need to be changed: ``` apiVersion: v1 kind: Pod metadata: name: random-number-generator spec: containers:
    • image: alpine name: alpine command: [“/bin/sh”,”-c”] args: [“shuf -i 0-100 -n 1 » /opt/number.out;”]

    volumes:

    • name: data-volume hostPath: path: /data type: Directory ```
  • Many other provisioners available.
    • Local, AzureFile, FlexVolume and more.
  • Another Storage Class example using a standard disk: 
    apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
 name: google-storage
provisioner: kubernetes.io/gce-pd
parameters:
 type: pd-standard
 replication-type: none
  • A second example with an SSD: 
    apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
 name: google-storage
provisioner: kubernetes.io/gce-pd
parameters:
 type: pd-ssd
 replication-type: none
  • A third example with an SSD and replication: 
    apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
 name: google-storage
provisioner: kubernetes.io/gce-pd
parameters:
 type: pd-ssd
 replication-type: regional-pd

Updated: