Create sharedv4 PVCs

This document describes how to use Portworx sharedv4 (ReadWriteMany) volumes in your Kubernetes cluster.

Pre-requisites

In order to use Portworx sharedv4 volumes, you need to pass the following environment variable to the Portworx DaemonSet.

  env:
    - name: "ENABLE_SHARED_AND_SHARED_v4"
      value: "true"

To edit an existing Portworx installation run the following commands:

Create a patch file

cat <<EOF> patch.yaml
spec:
  template:
    spec:
      containers:
      - name: portworx
        env:
          - name: ENABLE_SHARED_AND_SHARED_v4
            value: "true"
EOF

Patch the daemon set

kubectl -n kube-system patch ds portworx --patch "$(cat patch.yaml)" --type=strategic

After updating the daemon set, all the Portworx pods will restart. Once all the Portworx pods are restarted then you can start using sharedv4 volumes.

Provision a Sharedv4 Volume

Sharedv4 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-sharedv4-sc.yaml

Example:

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
    name: px-sharedv4-sc
provisioner: kubernetes.io/portworx-volume
parameters:
   repl: "2"
   sharedv4: "true"

Note the sharedv4 field in the list of parameters is set to true. Verifying storage class is created:

kubectl describe storageclass px-sharedv4-sc

Name:	  	   px-sharedv4-sc
IsDefaultClass:	   No
Annotations:	   <none>
Provisioner:	   kubernetes.io/portworx-volume
Parameters:	   repl=2,sharedv4=true
Events:			<none>

Step2: Create Persistent Volume Claim

Creating a ReadWriteMany persistent volume claim:

kubectl create -f examples/volumes/portworx/portworx-volume-sharedv4-pvc.yaml

Example:

kind: PersistentVolumeClaim
apiVersion: v1
metadata:
   name: px-sharedv4-pvc
   annotations:
     volume.beta.kubernetes.io/storage-class: px-sharedv4-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-sharedv4-pvc   Bound     pvc-a38996b3-76e9-11e7-9d47-080027b25cdf 10Gi       RWX           px-sharedv4-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-sharedv4-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-sharedv4-pvc

Starting pod-2

kubectl create -f examples/volumes/portworx/portworx-volume-sharedv4-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-sharedv4-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

Updating a shared volume to sharedv4 volume

You can update an existing shared volume to use the new v4 protocol and convert it into a sharedv4 volume. Run the following pxctl command to update the volume setting

pxctl volume update --sharedv4=on <vol-name>

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

Dynamic Provisioning of PVCs