- VSphere releases less than 7.0u2 are not supported for in-tree vSphere volume  as of Kubernetes...

For the 1.9 release, SIG Storage made Kubernetes more pluggable and modular by introducing an alpha implementation of the Container Storage Interface (CSI). CSI will make installing new volume plugins as easy as deploying a pod, and enable third-party storage providers to develop their plugins without the need to add code to the core Kubernetes codebase.

flexible alternative to `EmptyDir` volumes: as with `EmptyDir`, volumes are created and deleted for each pod automatically by Kubernetes. But because the normal provisioning process is used (`PersistentVolumeClaim`), storage can be provided by third-party storage vendors and all of the usual volume features work. Volumes don't need to be empty; for example, restoring from snapshot is supported. ([#92784](https://github.com/kubernetes/kubernetes/pull/92784), [@pohly](https://github.com/pohly)) [SIG API...