A method for driving a switch in a switched-mode power supply, in which the switch is connected in series with a primary coil of a transformer and in which a control signal dependent on an output voltage is available. The rate control section calculates the quantization parameter by using an average data size of the encoded data for previous N frames, and the frame skip section performs the skip processing when a frame in which the quantization parameter is greater than a threshold continues equal to or more than a number of times for a number threshold. Once data is received from a host, each of the plural storage systems creates write-data management information having sequential numbers and reference information and sends, to one of the primary storage systems, the data, sequential number and reference information. A read-back signal is generated corresponding to the portion of the data read from the removable data storage medium, which is used to detect if an error occurred in writing the portion of the data to the removable data storage medium. A first portion of the fan may be lower than a top edge of the backplane, and a second portion of the fan may be higher than the top edge of the backplane. The low load mode includes operating the power supply in zero voltage switching mode in response to an output voltage of the power supply falling below a regulation voltage threshold.