A data processing apparatus and a method of mounting a logical drive are provided which reduce the time required for completing start-up of an application. A priority level of each logical drive is determined based on access frequency by the automatically started applications in an initial setting processing of the applications in the previous start-up of the data processing apparatus. Higher priority is given to the logical drive having higher access frequency. For subsequently starting up the data processing apparatus, each logical drive is mounted in the order of the determined priority.