Browse Prior Art Database

HDD Write Instability Recovery Procedure

IP.com Disclosure Number: IPCOM000123123D
Original Publication Date: 1998-May-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 34K

Publishing Venue

IBM

Related People

Asano, H: AUTHOR [+8]

Abstract

Disclosed is a method to decrease dummy write operation frequency, to recover continuous write error due to head instability disturbance. In almost case, instability can be cleared by dummy write operation. But, dummy write operation needs time for seek operation to dedicated cylinder, or to head unload position.

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HDD Write Instability Recovery Procedure

   Disclosed is a method to decrease dummy write operation
frequency, to recover continuous write error due to head instability
disturbance.  In almost case, instability can be cleared by dummy
write operation.  But, dummy write operation needs time for seek
operation to dedicated cylinder, or to head unload position.

   Sometimes instability disturbance can be relaxed by head
bias voltage change in ERP (error recovery procedure) step.  (Not
completely) If normal write operation (with user data) becomes
possible with lower /higher bias voltage, that brings similar effect
as dummy write that clears instability completely.  With above idea,
bias voltage change is tried in ERP step, before going to dummy write
operation.

   Disclosed is a method to optimize HDD read performance in
real time, by changing head bias voltage, write current, with
in-file thermal sensor information (on flex cable, on card, or
inside  DE (disk enclosure)).  Higher head bias voltage at low
temperature, might be allowed without loosing head reliability
/life.  In such case, higher bias voltage increases signal
amplitude, and that improves read performance (SER (soft error
rate)).  Higher write current is selected at low temperature, over
write (OW) performance can be improved.  Lower write current is
selected at high temperature, squeeze margin can be improved by
reducing head write width that is getting wide, on disk.