DEFECTIVE SECTOR REPLACING METHOD FOR MAGNETIC DISK DEVICE

PURPOSE:To shorten time for accessing data by providing one alternative sector at least in each recorded track and replacing a sector, where a defect is generated, with the alternative sector of the same recorded track or the other recorded track close to the recorded track. CONSTITUTION:In each recorded track, the final sector is set to the alternative sector and the defective sector, which is generated in the same recorded track or the closed recorded track, is replaced with the alternative sector. For example, when the 5th sector and 36th sector of the 1st recorded track and the 37th track of the 4th recorded track are respectively the defective sector, the 5th sector and 36th sector of the 1st recorded track are respectively replaced by the alternative sectors of the 1st recorded track and 2nd recorded track and the 37th sector of the 4th recorded track is replaced by the alternative sector of the 4th recorded track. Accordingly, a distance between the defective sector and alternative sector is extremely reduced and time required for replacement processing is shortened. Thus, the data access time is shortened.