Browse Prior Art Database

Re-Assign in the Event of a "Hard" Write Inhibit

IP.com Disclosure Number: IPCOM000118515D
Original Publication Date: 1997-Mar-01
Included in the Prior Art Database: 2005-Apr-01
Document File: 2 page(s) / 53K

Publishing Venue

IBM

Related People

Blachek, MD: AUTHOR [+2]

Abstract

Servo errors in a hard disk drive which prevent the writing of data are circumvented by reassigning the defective area of the disk to a defect-free area. This is currently the practice for errors which occur while reading data but not for write inhibit errors.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 54% of the total text.

Re-Assign in the Event of a "Hard" Write Inhibit

      Servo errors in a hard disk drive which prevent the writing of
data are circumvented by reassigning the defective area of the disk
to a defect-free area.  This is currently the practice for errors
which occur while reading data but not for write inhibit errors.

      Hard disk drives often fail due to write inhibit errors.  These
errors are caused when the servo system responsible for the track
positioning of a read/write head detects that the head is not
properly positioned over the desired track.  The write inhibit error
instructs the disk drive not to write data as it is likely that data
on an adjacent track may be accidentally over-written.  Ordinarily,
write inhibit errors, which may be caused by some temporary
mechanical shock, do not repeat after a retry.  In some cases,
however, subsequent retries are not successful and it is currently
the practice to deem the disk drive unusable and to recommend that it
be replaced.  A write inhibit error that is not recoverable is called
a "hard" write inhibit error.

      While a hard write inhibit error requires that a disk drive
be replaced, a replacement is not always necessary.  For example,
oftentimes a hard write inhibit is caused by a local disk defect.
For Magnetoresistive (MR) playback heads, disk defects, which are
high enough to contact the MR head, can create thermal heating which
is known as a Thermal Asperity (TA).  TA defects are very loca...