A technique is described to enable exclusive control on a file basis in a storage system while remote double recording is performed between storage controllers. In this case, the feature points, which are mismatched, are removed as feature points which are mistracked between plural frames. Between the exhaust-gas guide member and the cover hood, an outside-air introduction gap is formed, through which outside air is introduced into the cover hood by ejector effects. The battery compartment holds a energy source such as battery.