Abstract: Embodiments of the present invention help improve the process for updating parities accompanied by the writing process. According to one embodiment, a host controller transmits a write command and new data to a hard disk drive (HDD). The HDD reads old data at a region where the new data are to be written. The HDD then XORs the new data and the old data to generate a pseudo-parity. The HDD sets the pseudo-parity in a data frame addressed to both of a horizontal parity disk drive HDD and a diagonal parity disk drive HDD and transmits it. The horizontal parity disk drive HDD and the diagonal parity disk drive HDD update the parities using the pseudo-parity.

Abstract: Embodiments of the present invention help improve the process for updating parities accompanied by the writing process. According to one embodiment, a host controller transmits a write command and new data to a hard disk drive (HDD). The HDD reads old data at a region where the new data are to be written. The HDD then XORs the new data and the old data to generate a pseudo-parity. The HDD sets the pseudo-parity in a data frame addressed to both of a horizontal parity disk drive HDD and a diagonal parity disk drive HDD and transmits it. The horizontal parity disk drive HDD and the diagonal parity disk drive HDD update the parities using the pseudo-parity.

Abstract: A positioning control method of a magnetic disc apparatus is provided which can permit fast and stable settling to a target position without overshoot or undershoot in connection with a moving distance of one track seek to about 16-track seek for which positioning must be determined within a moving time corresponding to a resonance frequency of a mechanical system. Such a method can also generate a position/velocity orbit for reducing power at a specified frequency, provide acceleration feed-forward compensation which can permit a head to accurately reach the target position even when the feedback system does not function under a condition that external disturbance does not act and generate a position orbit corrected by a controlled object model accurately modeling resonance oscillation up to a moving frequency band are used in combination.

Abstract: There is provided a positioning control method of magnetic disc apparatus which can permit fast and stable settling to a target position without overshoot or undershoot in connection with a moving distance of one track seek to about 16-track seek for which positioning must be determined within a moving time corresponding to a resonance frequency of a mechanical system. (1) a method of generating a position/velocity orbit for reducing power at a specified frequency, (2) a method of generating acceleration feed-forward compensation which can permit a head to accurately reach the target position even when the feedback system does not function under a condition that external disturbance does not act and (3) a method of generating a position orbit corrected by a controlled object model accurately modeling resonance oscillation up to a moving frequency band are used in combination.