GCEPersistentDiskVolumeSource
Represents a Persistent Disk resource in Google Compute Engine.
A GCE PD must exist before mounting to a container. The disk must also be in the same GCE project and zone as the kubelet. A GCE PD can only be mounted as read/write once or read-only many times. GCE PDs support ownership management and SELinux relabeling.