2.2.3.3 Server Drive I/O Request (DR_DRIVE_CORE_DEVICE_IOREQUEST)
The server issues a device I/O request on a redirected file system device. Each request begins with a DR_DEVICE_IOREQUEST (section 2.2.1.4) header, in which the DeviceId field MUST be set to a device that has been announced as a file system device.