Apparatus and methods are provided for delivering end-to-end Quality of Service over Internet Protocol networks. The sensor system has at least one sensor chip situated in the channel for determining the parameter of the fluid medium. The rotatable bracket defines a pivot hole, and a guiding notch communicating with the pivot hole. This method allows the write operation to continue without halting the system as with conventional RAID devices. The microprocessor, upon detecting a specific operational malfunctioning, actuating the positioning device and executing an emergency procedure according to which the same emergency signal is generated and output at the second signal transmission contact.