chapter-7-storage-7.md

Table of Contents

Chapter 7: Storage (7%)

• Manage Persistent Volume
• Volume Access Modes
• Manage Persistent Volume Claims
• Manage Storage Objects
• Configure Application with Storage

Storage

Manage Persistent Volume

Command References

 apiVersion: v1
 kind: PersistentVolume
 metadata:
   name: pv0003
 spec:
   capacity:
     storage: 5Gi
   volumeMode: Filesystem
   accessModes:
     - ReadWriteOnce
   persistentVolumeReclaimPolicy: Recycle
   storageClassName: slow
   mountOptions:
     - hard
     - nfsvers=4.1
   nfs:
     path: /tmp
     server: 172.17.0.2

References and Further Study

• https://kubernetes.io/docs/concepts/storage/volumes/

Volume Access Modes

A PersistentVolume can be mounted on a host in any way supported by the resource provider. As shown in the table below, providers will have different capabilities and each PV’s access modes are set to the specific modes supported by that particular volume. For example, NFS can support multiple read/write clients, but a specific NFS PV might be exported on the server as read-only. Each PV gets its own set of access modes describing that specific PV’s capabilities. The access modes are:

• ReadWriteOnce – the volume can be mounted as read-write by a single node
• ReadOnlyMany – the volume can be mounted read-only by many nodes
• ReadWriteMany – the volume can be mounted as read-write by many nodes

In the CLI, the access modes are abbreviated to:

• RWO - ReadWriteOnce
• ROX - ReadOnlyMany
• RWX - ReadWriteMany

References and Further Study

• https://kubernetes.io/docs/concepts/storage/persistent-volumes/

Manage Persistent Volume Claims

Command References

 apiVersion: v1
 kind: PersistentVolumeClaim
 metadata:
   name: myclaim
 spec:
   accessModes:
     - ReadWriteOnce
   volumeMode: Filesystem
   resources:
     requests:
       storage: 8Gi
   storageClassName: slow
   selector:
     matchLabels:
       release: "stable"
     matchExpressions:
       - {key: environment, operator: In, values: [dev]}

References and Further Study

• https://kubernetes.io/docs/concepts/storage/persistent-volumes/#persistentvolumeclaims

Manage Storage Objects

Volumes are already use by a pod are protected against dataloss. This means that even if you delete a PVC, you can access the volume from POD.

Command References

 $ kubectl get pv
 $ kubectl get pvc

References and Further Study

• https://kubernetes.io/docs/concepts/storage/storage-classes/

Configure Application with Storage

Command References

 apiVersion: v1
 kind: Pod
 metadata:
   name: mypod
 spec:
   containers:
     - name: myfrontend
       image: nginx
       volumeMounts:
       - mountPath: "/var/www/html"
         name: mypd
   volumes:
     - name: mypd
       persistentVolumeClaim:
         claimName: myclaim

References and Further Study

Table of Contents
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