Browse Prior Art Database

Servo Parameter Measurement After GMR Reset

IP.com Disclosure Number: IPCOM000123441D
Original Publication Date: 1998-Nov-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 2 page(s) / 68K

Publishing Venue

IBM

Related People

Okutsu, K: AUTHOR [+3]

Abstract

1. Summary of New Technique Disclosed is the new ERP (Error Recovery Procedure) technique which measures the Servo Parameter after GMR (Giant Magnetoresistive) Reset is executed in the ERP. 2. Current Technique Explanation Sometimes GMR head condition is changed during Write operation, then GMR head cannot write and read correctly after this head condition change. This is called "Instability". When "Instability" occurs "GMR reset" is done in ERP to recover head condition. However GMR reset changes the Read out amplitude and resolution. This change causes "Bad stability" and "long seek time" which may be the reason of bad performance. 3. Detail of this Disclosure Servo parameter remeasurement is done when GMR reset is executed.

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Servo Parameter Measurement After GMR Reset

  1.  Summary of New Technique
  Disclosed is the new ERP (Error Recovery Procedure) technique
  which measures the Servo Parameter after GMR
  (Giant Magnetoresistive) Reset is executed in the ERP.
  2.  Current Technique Explanation
  Sometimes GMR head condition is changed during Write operation,
  then GMR head cannot write and read correctly after this head
  condition change.  This is called "Instability".  When
  "Instability" occurs "GMR reset" is done in ERP to recover
  head condition.  However GMR reset changes the Read out
  amplitude and resolution.  This change causes "Bad stability"
  and "long seek time" which may be the reason of bad
  performance.
  3.  Detail of this Disclosure
  Servo parameter remeasurement is done when GMR reset is
  executed.  This remeasurement is done during IDLE time
  in order to avoid performance degradation.  Remeasurement
  is done with following steps.
    1.  When GMR reset is done in ERP, the flag which indicates
        "GMR resetted" head number is turned on.
    2.  If HDD (Hard Disk Drive) firmware detects this flag is
        enabled during IDLE, firmware remeasures the "Servo
        Parameter".  This remeasurement is done at IDLE whose
        interruption level is lower than host interruption
        level.  Therefore this remeasurement doesn't degrade
        drive performance.
    3.  Firmwa...