From df79bf9c5e4447ec3f37fceeecdc80310040dbb7 Mon Sep 17 00:00:00 2001
From: Srini Brahmaroutu <srbrahma@us.ibm.com>
Date: Thu, 23 Aug 2018 11:00:19 -0700
Subject: [PATCH] Documenting FlexVolume Resize alpha feature.

---
 .../en/docs/concepts/storage/persistent-volumes.md  | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/content/en/docs/concepts/storage/persistent-volumes.md b/content/en/docs/concepts/storage/persistent-volumes.md
index 28fc8b4f1a1ef..8ddef8907ae8b 100644
--- a/content/en/docs/concepts/storage/persistent-volumes.md
+++ b/content/en/docs/concepts/storage/persistent-volumes.md
@@ -226,9 +226,22 @@ kubectl describe pvc <pvc_name>
 ```
 
 If the `PersistentVolumeClaim` has the status `FileSystemResizePending`, it is safe to recreate the pod using the PersistentVolumeClaim.
+{{< feature-state for_k8s_version="v1.12" state="alpha" >}}
+FlexVolumes allow resize if the driver is set with the `RequiresFSResize` capability to true. Since this is a alpha feature
+both  `ExpandInUsePersistentVolumes` and `ExpandPersistentVolumes` feature gates must be enabled.
 
 #### Resizing an in-use PersistentVolumeClaim
 
+{{< feature-state for_k8s_version="v1.12" state="alpha" >}}
+Expanding in-use PVCs for FlexVolumes is an alpha feature. To enable this feature use  `ExpandInUsePersistentVolumes` 
+and `ExpandPersistentVolumes` feature gates. The FlexVolume plugin uses RequiresFSResize to identify and resize the 
+Persistent Volume. The underlying driver must support resize, if not an error will be returned and Persistent Volume 
+object will not change and the expand request will fail. FlexVolume driver must implement the method `ExpandFS` defined
+in the interface `FSResizableVolumePlugin` along with `ExpandableVolumePlugin` interface and its method `ExpandVolumeDevice`.
+The flex driver should implement ExpandableVolumePlugin interface only if it is to be installed on the controller/master.
+The flex driver should implement any volume expansion methods along with FS resize in ExpandFS method if the flex driver 
+is installed on the worker nodes but not on the controller/master node.
+
 {{< feature-state for_k8s_version="v1.11" state="alpha" >}}
 
 Expanding in-use PVCs is an alpha feature. To use it, enable the `ExpandInUsePersistentVolumes` feature gate.