Browse Prior Art Database

A Defect Mapping Method to Prevent a Hard Error

IP.com Disclosure Number: IPCOM000123654D
Original Publication Date: 1999-Feb-01
Included in the Prior Art Database: 2005-Apr-05
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Kisaka, M: AUTHOR [+3]

Abstract

A method for mapping defects on a disk in a hard disk drive (HDD) is disclosed. The HDD stores data in sectors. The data flow in a hard disk drive is shown in Fig.1. The data in the sector read by a head is sent to a hard disk controller (HDC) and the HDC correct the data using error correction code (ECC) attached to the data if the data has erroneous bits. The proposed method utilizes this ECC capability for searching defects. To find the defects, thresholds for amplitude and time interval are set as Fig. 2. If the amplitude of the signal is less than L1 during more than T1 time interval, a value other than zero is set to the bit of the data just after T1. If the sector has such a defect at other places, the data has several non-zero bits. This data is sent to the HDC, and the HDC performs error correction.

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A Defect Mapping Method to Prevent a Hard Error

   A method for mapping defects on a disk in a hard disk
drive (HDD) is disclosed.  The HDD stores data in sectors.  The data
flow in a hard disk drive is shown in Fig.1.  The data in the sector
read by a head is sent to a hard disk controller (HDC) and the HDC
correct the data using error correction code (ECC) attached to the
data if the data has erroneous bits.  The proposed method utilizes
this ECC capability for searching defects.  To find the defects,
thresholds for amplitude and time interval are set as Fig. 2.  If the
amplitude of the signal is less than L1 during more than T1 time
interval, a value other than zero is set to the bit of the data just
after T1.  If the sector has such a defect at other places, the data
has several non-zero bits.  This data is sent to the HDC, and the HDC
performs error correction.  As the ECC for all zero data is zero, the
HDC can correct a few errors in the data.  Therefore the sector with
several errors can be detected.  If the sector has several errors,
all sectors surrounding the sector is mapped as defect (Fig. 3).
This method can protect escape of defects.