A method for a hard disk controller comprising a plurality of platters, for improving the reliability of the hard disk, each platter comprising at least one data storage surface, the method comprising the following steps of: - obtaining a plurality of data blocks, each block of said plurality of data blocks having to be or being stored in the hard disk, the number of blocks of said plurality of data blocks being lower than the number of platter surfaces of the hard disk which can store data; - calculating (305, 505) at least one redundancy data block as a function of each block of said plurality of data blocks, the number of redundancy data block added to the number of blocks of said plurality of data blocks being lower than or equal to the number of platter surfaces of the hard disk which can store data; - writing (320, 510) said at least one redundancy data block on a platter surface of the hard disk, distinct from the surfaces used to store each block of said plurality of data blocks; - accessing a plurality of data blocks corresponding to a piece of data to be read in the hard disk and accessing at least one redundancy data block corresponding to said piece of data to be read, each block of said plurality of data blocks accessed and each redundancy data block associated with said piece of data to be read being accessed on a distinct platter surface of the hard disk; the method being characterised in that it furthermore comprises the following steps of: - checking the integrity of the piece of data corresponding to said plurality of data blocks accessed according to said at least one redundancy data block corresponding to said piece of data to be read to detect a potential reading error; - storing a reading error of a piece of data in the hard disk; and - estimating a reliability state of a given platter surface of said hard disk for which most errors were detected during a given time period. - obtaining a plurality of data blocks, each block of said plurality of data blocks having to be or being stored in the hard disk, the number of blocks of said plurality of data blocks being lower than the number of platter surfaces of the hard disk which can store data; - calculating (305, 505) at least one redundancy data block as a function of each block of said plurality of data blocks, the number of redundancy data block added to the number of blocks of said plurality of data blocks being lower than or equal to the number of platter surfaces of the hard disk which can store data; - writing (320, 510) said at least one redundancy data block on a platter surface of the hard disk, distinct from the surfaces used to store each block of said plurality of data blocks; - accessing a plurality of data blocks corresponding to a piece of data to be read in the hard disk and accessing at least one redundancy data block corresponding to said piece of data to be read, each block of said plurality of data blocks accessed and each redundancy data block associated with said piece of data to be read being accessed on a distinct platter surface of the hard disk; the method being characterised in that it furthermore comprises the following steps of: - checking the integrity of the piece of data corresponding to said plurality of data blocks accessed according to said at least one redundancy data block corresponding to said piece of data to be read to detect a potential reading error; - storing a reading error of a piece of data in the hard disk; and - estimating a reliability state of a given platter surface of said hard disk for which most errors were detected during a given time period. - checking the integrity of the piece of data corresponding to said plurality of data blocks accessed according to said at least one redundancy data block corresponding to said piece of data to be read to detect a potential reading error; - storing a reading error of a piece of data in the hard disk; and - estimating a reliability state of a given platter surface of said hard disk for which most errors were detected during a given time period.