Drivers of mass-storage devices that have internal caches for data must handle this request in a DispatchShutdown routine. Drivers of mass-storage devices and intermediate drivers layered over them also must handle this request if an underlying driver maintains internal buffers for data.
Receipt of a shutdown request indicates that a file system driver is sending notice that the system is being shut down.
One or more file system drivers can send such a lower-level driver more than one shutdown request when a user logs off or when the system is being shut down for some other reason.
The driver must complete the transfer of any data currently cached in the device or held in the driver's internal buffers before completing the shutdown request.