A tractor comprises a tractor frame, driven ground engaging means, and an electronic tractor controller. The regulating device including a body provided at least with one feed channel and one outflow channel put into communication by an aperture within the interior of which a valving element is movable provided with a perimetral lateral surface in which at least one window is provided in communication with a free end of the valving element. The system can thus be accessed and controlled remotely. The burst buffer appliance can optionally store checkpoint data that results from the asynchronous checkpointing operations. A principal phase in the glass-ceramic is BaTi4O.