Create shared PVCs

This document describes how to use Portworx shared (ReadWriteMany) volumes in your Kubernetes cluster. If you wish to create sharedv4 volumes refer here

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.

Openshift users:

The following sections describe how you can create shared PVCs using the native in-tree Portworx driver in Kubernetes. If you’re running Portworx on Openshift 3.11 or earlier, shared volumes work only if SELinux is disabled on the node or in Docker. This issue is caused by a bug in Kubernetes, which is fixed in Kubernetes 1.13.4 and is shipped with OpenShift 4.1.

Please refer to the instructions from the Shared PVCs using CSI page to create shared Portworx PVCs.

Step 1: Create Storage Class

Create the storageclass:

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

Example:

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
    name: px-shared-sc
provisioner: kubernetes.io/portworx-volume
parameters:
   repl: "1"
   shared: "true"

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>

Step 2: Create Persistent Volume Claim

Creating a ReadWriteMany 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

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

Step 3: 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

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

Verifying pods are running:

kubectl get pods

NAME      READY     STATUS    RESTARTS   AGE
pod1      1/1       Running   0          2m
pod2      1/1       Running   0          1m

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

Using Pre-provisioned Volumes

Create shared PVCs using CSI