// More info: https://kubernetes.io/docs/concepts/storage/volumes#nfs
  // +optional
  optional NFSVolumeSource nfs = 5;

  // rbd represents a Rados Block Device mount on the host that shares a pod's lifetime.
  // More info: https://examples.k8s.io/volumes/rbd/README.md
  // +optional
  optional RBDPersistentVolumeSource rbd = 6;

  // iscsi represents an ISCSI Disk resource that is attached to a

given element may be less than the index of the same element in the
underlying array.
</p>
<p>
A slice, once initialized, is always associated with an underlying
array that holds its elements.  A slice therefore shares storage
with its array and with other slices of the same array; by contrast,
distinct arrays always represent distinct storage.
</p>
<p>
The array underlying a slice may extend past the end of the slice.