International Business Machines Corporation

Hitachi Global Storage Technologies Netherlands B.v.

Hoan Andrew Au

Bernd Lamberts

Arvind M Patel

Kris Victor Schouterden

David H Jen

Bum Suck So

Robert A Rutledge

Robert Yuan-Shih Li

Douglas Michael Zuercher

Peter Cheng-I Fang

Weining Zeng

Theofilos George Fkiaras

Xiang-Jun (Leon) Feng

Albert S Su

Data recovery information characterizes data recovery procedure (DRP) steps to be performed within a hard disk drive (HDD) in response to a miss. Particular data recovery information corresponds to a radial position of the actuator and, therefore, the position of the magnetic recording read/write head relative to the associated storage media at the location at which the miss occurred. The data recovery information is based on the physical shape of a write pole and on how the physical shape of the pole inherently affects operational data error associated with the head. Because of the foregoing characteristics of such data recovery information, a more efficient and performant data recovery procedure is performed based thereon.

Adaptive data recovery procedure based on radial positioning

A method and apparatus for detecting disk drive head instability. Normal head fluctuation is removed from the criterion used to detect whether a head is unstable. The present invention accumulates error signals in an accumulator and calculates a criterion having an average fluctuation removed using the accumulated error signals. The criterion is calculated according to (max&plus;min)&minus;(2&times;average), wherein max is the maximum error signal, min is the minimum error signal and average is the average error signal. The criterion is then compared to a predetermine threshold to determine whether the head is unstable. A head is determined to be unstable when (max&plus;min)&minus;(2&times;average) is greater than the predetermined threshold.

Method and apparatus for testing MR head instability using a criterion that removes normal head fluctuation from consideration

A method and apparatus for providing amplitude instability data recovery for AMR/GMR heads during amplitude loss using MSE and/or amplitude envelope detection procedures. The method includes (a) initiating a data recovery procedure by selecting a detection mode for detecting when an error condition occurs, (b) performing the selected detection mode, (c) determining a reset action for resetting the magnetic head, (d) performing the reset action to reset the magnetic head and (f) re-reading data in the track after performing the reset action. An embodiment of the invention further includes (g) determining whether the resetting of the magnetic head allowed recovery of the data in the track and (h) terminating the data recovery procedure when the data is recovered. An embodiment of the invention further includes (i) determining whether predetermined limits have been exhausted when the data is not recovered, (j) terminating the data recovery procedure when the predetermined limits have been exhausted and repeating steps (a)-(g) when the predetermined limits have not been exhausted. In an embodiment of the invention, the determining a reset action for resetting the magnetic head further includes applying a maximum write current to the head, toggling a head bias current, toggling the head bias current and the write current, or applying a reset pulse to the head.

Method and apparatus for providing amplitude instability data recovery for AMR/GMR heads

Method and circuitry for phase synchronizing an analog input signal with a clock signal by sensing clock delay error, adjusting in increments clock delay trim of a delay element that initially has an arbitrary delay setting, and stopping adjustment after differential delay between the signals has been eliminated.

Clock delay trim adjustment with stopping feature for eliminating

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Palo Alto, CA, United States of America

Hoan Andrew Au