Magnetic disk device and its disk access method

To access the large volume files of a plurality of systems on the magnetic disk (7), it requires to store the history of the commands to determine if the access is continuous or not. When the continuity of a plurality of systems is checked and verified, the access of the magnetic disk (7) is not based on the data lengths as dictated by the command, but rather it is executed according to the track units corresponding to the operation conditions of the various systems. When accessing a plurality of large volume continuous data, to use the sector number of each track as the magnetic disk (7) access unit, and to restrict the occurrences of the search, to enable it to handle the transmission of the data in a short time, as so to reduce the number of search and to raise the transmission efficiency.