update readme for raw block pvc

Signed-off-by: Madhu Rajanna <madhupr007@gmail.com>

examples/README.md

@@ -216,3 +216,65 @@ spec:
 
 If you access the pod you can check that your data is avaialable at
 `/var/lib/www/html`
+
+## Testing Raw Block feature in kubernetes with RBD volumes
+
+CSI block volume support is feature-gated and turned off by default. To run CSI
+with block volume support enabled, a cluster administrator must enable the
+feature for each Kubernetes component using the following feature gate flags:
+
+--feature-gates=BlockVolume=true,CSIBlockVolume=true
+
+these feature-gates must be enabled on both api-server and kubelet
+
+### create a raw-block PVC
+
+```yaml
+apiVersion: v1
+kind: PersistentVolumeClaim
+metadata:
+  name: raw-block-pvc
+spec:
+  accessModes:
+    - ReadWriteOnce
+  volumeMode: Block
+  resources:
+    requests:
+      storage: 1Gi
+  storageClassName: csi-rbd
+```
+
+create raw block pvc
+
+```console
+kubectl create -f raw-block-pvc.yaml
+```
+
+### create a pod to mount raw-block PVC
+
+```yaml
+---
+apiVersion: v1
+kind: Pod
+metadata:
+  name: pod-with-raw-block-volume
+spec:
+  containers:
+    - name: fc-container
+      image: fedora:26
+      command: ["/bin/sh", "-c"]
+      args: [ "tail -f /dev/null" ]
+      volumeDevices:
+        - name: data
+          devicePath: /dev/xvda
+  volumes:
+    - name: data
+      persistentVolumeClaim:
+        claimName: raw-block-pvc
+```
+
+Create a POD that uses raw block PVC
+
+```console
+kubectl create -f raw-block-pod.yaml
+```