This document describes how to use portworx shared volumes in your Kubernetes cluster.

Provision a Shared Volume

Shared volumes are useful when you want multiple PODs to access the same PVC (volume) at the same time. They can use the same volume even if they are running on different hosts. They provide a global namespace and the semantics are POSIX compliant.

Step1: Create Storage Class

Create the storageclass:

# kubectl create -f examples/volumes/portworx/portworx-shared-sc.yaml

Example:

kind: StorageClass
apiVersion: storage.k8s.io/v1beta1
metadata:
    name: px-shared-sc
provisioner: kubernetes.io/portworx-volume
parameters:
   repl: "1"
   shared: "true"

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Note the shared field in the list of parameters is set to true. Verifying storage class is created:

# kubectl describe storageclass px-shared-sc
Name:	  	   px-shared-sc
IsDefaultClass:	   No
Annotations:	   <none>
Provisioner:	   kubernetes.io/portworx-volume
Parameters:	   repl=1,shared=true
Events:			<none>

Step2: Create Persistent Volume Claim.

Creating the persistent volume claim:

# kubectl create -f examples/volumes/portworx/portworx-volume-shared-pvc.yaml

Example:

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
   name: px-shared-pvc
   annotations:
     volume.beta.kubernetes.io/storage-class: px-shared-sc
spec:
   accessModes:
     - ReadWriteMany
   resources:
     requests:
       storage: 10Gi

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Note the accessMode for this PVC is set to ReadWriteMany so the kubernetes allows mounting this PVC on multiple pods.

Verifying persistent volume claim is created:

# kubectl get pvc
NAME            STATUS    VOLUME                                   CAPACITY   ACCESSMODES   STORAGECLASS   AGE
px-shared-pvc   Bound     pvc-a38996b3-76e9-11e7-9d47-080027b25cdf 10Gi       RWX           px-shared-sc   12m

Step3: Create Pods which uses Persistent Volume Claim.

We will start two pods which use the same shared volume.

Starting pod-1

# kubectl create -f examples/volumes/portworx/portworx-volume-shared-pod-1.yaml

Example:

apiVersion: v1
kind: Pod
metadata:
  name: pod1
spec:
  containers:
  - name: test-container
    image: gcr.io/google_containers/test-webserver
    volumeMounts:
    - name: test-volume
      mountPath: /test-portworx-volume
  volumes:
  - name: test-volume
    persistentVolumeClaim:
      claimName: px-shared-pvc

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Starting pod-2

# kubectl create -f examples/volumes/portworx/portworx-volume-shared-pod-2.yaml

Example:

apiVersion: v1
kind: Pod
metadata:
  name: pod2
spec:
  containers:
  - name: test-container
    image: gcr.io/google_containers/test-webserver
    volumeMounts:
    - name: test-volume
      mountPath: /test-portworx-volume
  volumes:
  - name: test-volume
    persistentVolumeClaim:
      claimName: px-shared-pvc

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Verifying pods are running:

# kubectl get pods
NAME      READY     STATUS    RESTARTS   AGE
pod1      1/1       Running   0          2m
pod2      1/1       Running   0          1m

Note: To access PV/PVCs with a non-root user refer here