Abstract: A hard disk drive (HDD) provides for the logical removal of defective physical heads. The HDD includes one or more disks organized into a plurality of regions, each region having a plurality of physical block addresses (PBAs). A number of physical heads are used to read and write information to the disks. A controller is configured to translate logical block addresses (LBAs) received from an external system to PBAs used to access the one or more disks, wherein the controller is configured to logically remove a defective physical head from service by dynamically re-assigning LBAs to each of the plurality of regions while preventing LBAs from being assigned to regions associated with the defective physical head.

Abstract: A system which reduces power dissipation in a data storage device having a normal operating mode and at least one power saving mode by computing a predicted amount of power that would be saved by the device if the device makes a transition from the normal operating mode to the power saving mode; computing a time at which the device should transition from the normal operating mode to the power saving mode, based on at least one predicted amount of power to be saved; and transitioning the device from the normal operating mode to the power saving mode.

Abstract: A data storage system, a storage medium and a method of controlling a data storage system are described, which allow defects on a storage medium to be handled with a memory region of a reduced size. In one embodiment defective sectors are determined on a magnetic disk and recorded in a defect map as a starting address and a number (length) of consecutive defective sectors to more efficiently record defective sector bursts than in the prior art. Optionally a mixed format defect map may record defective sector bursts as above and single sector defects as an address without a number of consecutive defective sectors.

Abstract: A disk drive with means to prevent accidental landing of a head/slider on the disk surface is described. In one embodiment a shock sensor is provided to sense external shocks received by the mechanism. During loading (positioning) of the actuator bearing the head/slider over the disk, if a shock is sensed, loading is stopped and an immediate unloading is performed to return the actuator to the withdrawn position. In another embodiment the unload operation is performed when the rotational speed of the disk is changed. In another embodiment the unload operation is performed when the rotational speed of the disk drops below a threshold. A circuit and method for detecting when the rotational speed of the disk drops below a threshold is also provided. The unloading in the various embodiments may be performed using velocity control or without velocity control.

Abstract: The present invention provides a disk drive, a load/unload unit, and a control method thereof which are capable of reliably unloading a head slider from a disk when power is turned off and enhancing reliability. A disk drive is equipped with a VCM spindle driver for rotating a disk, a magnetic head, an actuator mechanism for moving over the surface of the magnetic disk or to an evacuating position a head slider having the magnetic head, a ramp block, and a CPU/HDC (control means) for performing control of load and unload operations, speed control of the actuator mechanism, and control of an operation of reading or writing data from or to the disk. The CPU/HDC receives a specific command issued from the host immediately before power is turned off, and executes this command, then executes unload control, and notifies the host of command completion after the unload control has been completed.

Abstract: The present invention determines whether a filter is used for reading and writing on a disk to correct repeatable runout. The invention estimates the magnitude of repeatable runout for each disk by measuring the maximum absolute value of a state variable of a filter when the disk is turned on or when the disk returns from a sleep mode, and compares the measured value to a predetermined criterion such as the track width. If the magnitude of the repeatable runout is less than or equal to the predetermined criterion, the filter is not used. If the magnitude of the repeatable runout exceeds the predetermined criterion, the invention reads and writes data using the filter.

Abstract: A disk drive apparatus and read error recovery method in a disk drive apparatus removes thermal asperities on disk surfaces. A projection, such as a thermal asperity, on the recording surfaces of disks is detected when a signal transducer head contacts the projection. The flying height of the signal transducer head is lowered, e.g., by changing the disk rotation speed from the normal rotation speed in read/write operations or by heating a suspension having a bimetal element, while the signal transducer head is positioned over the detected projection on the track. The signal transducer head strikes the projection to break the projection. This avoids a subsequent error from being caused by the thermal asperity.

Abstract: A disk drive having embedded servo information accesses data without using sector identifier recorded in each sector. When a signal sector pulse signal (SP) at the end of a servo area is detected in a dead state during start up, a first data state for the start of a sector transits to a second data state for the litter region of the sector being divided in accordance with the capacity stored in a current sector's pointer register. At the beginning of the sector, the contents of a next sector's pointer register is stored in current sector's pointer register and the contents of a next sector's operation register is stored in a current sector's operation register. Upon completion of sector processing, the first data state is maintained when the next sector is contiguous. When a terminate instruction is stored in current sector's operation register, the process moves to dead state. When the servo area arrives, the process moves to idle state.