Abstract: Embodiments of the present invention help to efficiently determine the appropriate setting of the write current of a magnetic head relative to temperature. According to one embodiment, a test computer determines the set value of a write current as a function of temperature for each head device portion from the relationship between a write current and an error rate. A test execution controller sets a selected head device portion and a write current to an AE, and writes data on a magnetic disk using the components in a HDD. The test execution controller reads the written data, and the error rate of the data from an error correcting section. The test execution controller repeats the same process with the write current varied. Upon completion of the measurement at the preset write currents, the test execution controller transfers the measurement data to the test computer.

Abstract: Embodiments of the invention prevent offtrack write that will be caused due to a head vibration in a storage device. In one embodiment, a hard disk drive (HDD) judges approval/disapproval of write of user data to a magnetic disk by using a read signal for user data in addition to servo data in write processing. Thus, a head vibration which cannot be precisely detected based on servo data is detected to prevent off-track write. More specifically, the HDD acquires a read back signal amplitude of a read element with respect to a user data sector within adjacent servo data during a write access phase, and detects a vibration from a maximum value MAX and a minimum value MIN of the read back signal amplitude to judge data write approval/disapproval.

Abstract: Embodiments of the invention avoid an off-track write when an impact is applied. A hard disk drive according to one embodiment of the present invention comprises a magnetic disk; an actuator for moving a head element section over the magnetic disk; and an HDC/MPU for prohibiting the head element section from writing onto the magnetic disk for a short period when a detected impact is found to be greater than a low reference level and not greater than a high reference level, and prohibiting the head element section from writing onto the magnetic disk for a period longer than the short period when the detected impact is found to be greater than the high reference level.

Abstract: Embodiments of the present invention help to efficiently determine the appropriate setting of the write current of a magnetic head relative to temperature. According to one embodiment, a test computer determines the set value of a write current as a function of temperature for each head device portion from the relationship between a write current and an error rate. A test execution controller sets a selected head device portion and a write current to an AE, and writes data on a magnetic disk using the components in a HDD. The test execution controller reads the written data, and the error rate of the data from an error correcting section. The test execution controller repeats the same process with the write current varied. Upon completion of the measurement at the preset write currents, the test execution controller transfers the measurement data to the test computer.

Abstract: Embodiments of the invention prevent offtrack write that will be caused due to a head vibration in a storage device. In one embodiment, a hard disk drive (HDD) judges approval/disapproval of write of user data to a magnetic disk by using a read signal for user data in addition to servo data in write processing. Thus, a head vibration which cannot be precisely detected based on servo data is detected to prevent off-track write. More specifically, the HDD acquires a read back signal amplitude of a read element with respect to a user data sector within adjacent servo data during a write access phase, and detects a vibration from a maximum value MAX and a minimum value MIN of the read back signal amplitude to judge data write approval/disapproval.

Abstract: Embodiments of the invention provide a magnetic disk drive that does not generate errors when information is read even if considerable time has elapsed after the information was written on the magnetic disk. In one embodiment, a magnetic disk has a storage area divided into a plurality of sectors ST1. Time stamps TP1 corresponding to each sector data m1 stored in the sectors ST1 are stored in a time stamp recording medium. A processor controls the magnetic disk drive to read time stamps TP2 of sector data m2 stored in any sectors ST2 of the sectors ST1 and refresh sector data m3 selected based on an elapsed time calculated from information about the time when the time stamps are read and the time stamps TP2.

Abstract: Embodiments of the invention avoid an off-track write when an impact is applied. A hard disk drive according to one embodiment of the present invention comprises a magnetic disk; an actuator for moving a head element section over the magnetic disk; and an HDC/MPU for prohibiting the head element section from writing onto the magnetic disk for a short period when a detected impact is found to be greater than a low reference level and not greater than a high reference level, and prohibiting the head element section from writing onto the magnetic disk for a period longer than the short period when the detected impact is found to be greater than the high reference level.

Abstract: Embodiments of the invention provide a magnetic disk drive that does not generate errors when information is read even if considerable time has elapsed after the information was written on the magnetic disk. In one embodiment, a magnetic disk has a storage area divided into a plurality of sectors ST1. Time stamps TP1 corresponding to each sector data m1 stored in the sectors ST1 are stored in a time stamp recording medium. A processor controls the magnetic disk drive to read time stamps TP2 of sector data m2 stored in any sectors ST2 of the sectors ST1 and refresh sector data m3 selected based on an elapsed time calculated from information about the time when the time stamps are read and the time stamps TP2.

Abstract: A magnetic head has a left side rail formed on a disk facing surface in a protruded manner, and a right side rail formed on the disk facing surface in a protruded manner. A cross rail formed on the disk facing surface protrudes and is elongated continuously to both the left side rail and the right side rail. A left air bearing surface is formed on the disk facing surface in a protruded manner, and formed only on a side of a leading edge continuously from the left side rail. The left air bearing surface has a continuous portion to the left side rail, and a right air bearing surface which is formed on the disk facing surface in a protruded manner, formed only on a side of the leading edge continuously from the right side rail.

Abstract: A disk drive and a control method thereof to reduce the number of write operations to a medium while minimizing command overhead time. A disk drive 10 comprises a hard disk controller (HDC) 13, a cache memory 14, and a host interface controller (HIC) 15 with a command queue for retaining a plurality of commands which are cached in cache memory 14. The HIC 15 performs the periphery interface processing by hardware. The disk drive 10 further comprises a local microprocessor unit (MPU) 16 for controlling the overall operation of HDD 10, including operations of HDC 13 and HIC 15. The local MPU 16 instructs the HIC 15 to write data to a medium by write commands cached in the cache memory 14. When local MPU 16 retrieves a command from a plurality of write commands cached in cache memory 14 which is completely overwritten by a command more recently issued, a write operation to the medium is not performed by the retrieved command.

Abstract: An error recovery procedure (ERP) in a storage device such as a rotating magnetic hard disk drive is executed to the last step regardless of the established time-out period for an instruction, thereby more reliably recovering from errors. In accordance with one embodiment of the invention, when a disk drive receives a reset instruction from a host during the execution of an ERP, it executes the ERP until the error is recovered, or to the last step without interrupting the ERP. Further, in accordance with another embodiment of the invention, when a disk drive receives a reset instruction during the execution of an ERP, it stops execution of the ERP and holds the number K of the step which was completed immediately before stopping, and when receiving a retry instruction after that, sequentially executes the ERP from the K+1-th error recovery step.

Abstract: The present invention provides a method and apparatus to efficiently switch heads in a disk drive. A disk drive comprises a plurality of recording surfaces and a plurality of heads and each head is opposed to a recording surface. The heads are used for reading data from or writing data to the plurality of recording surfaces. An offset quantity table stores an offset quantity for each of the plurality of heads. The offset quantity is a value representative of the distance of a head with respect to a reference head. A head sequence table stores a predetermined head switching sequence. Head switching operations use the head switching sequence stored in the head sequence table.

Abstract: In the slider 1 on which a transducer 5 is mounted and which moves above a recording surface 4, in order to generate different vibration modes according to various situations such as vertical lift-off and landing, and breaking away from stiction, etc. A plurality of piezo-electric elements 8A, 8B, 8C, and 8D are disposed on the slider 1 and means for supplying a different AC voltage to each of the piezo-electric elements 8A, 8B, 8C, and 8D is provided.

Abstract: A magnetic head device comprising a magnetic core member made from a magnetic material having a positive magnetostriction constant and having confronting pole pieces separated by a non-magnetic material to form a transducing gap. A coil is wound around the magnetic core member so that a read signal can be read out from the coil, and a d.c. bias magnetic field is generated in the magnetic core member when a read signal is read out from the coil so that distortion of the read signal is suppressed.