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Protecting Data Loss with Preparing Shadow Head Coupled with Original Head

IP.com Disclosure Number: IPCOM000015882D
Original Publication Date: 2002-Aug-21
Included in the Prior Art Database: 2003-Jun-21
Document File: 3 page(s) / 80K

Publishing Venue

IBM

Abstract

D isclosed is a method for Protecting Data Loss with Preparing Shadow Head Coupled with Original Head in a Hard Disk Drive(HDD).

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Protecting Data Loss with Preparing Shadow Head Coupled with Original Head

Disclosed is a method for Protecting Data Loss with Preparing Shadow Head Coupled with Original Head in a Hard Disk Drive(HDD).

In this invention, when read error occurs with cause of disk defect, it is the first purpose to prevent data loss with restoring automatically using backup data(we call this as Shadow data). Moreover, data loss can be protected from not only with cause of disk defect but also of fatal head defect by using two modes "Usual-Couple-Mode" and "Emergency-Single-Mode" newly prepared. Therefore reliability will be raised more nearly further.

This invention is aimed at mobile HDD which have even Heads. The capacity of HDD is divided into two and one is used as a Backup.

Format:

The example of a format is shown below for HDD with 4 Heads. Original data and Shadow data are made to correspond one-to-one for LBA.

Write process:

The process of write operation is shown below. Write data handling

H ost P C <- -> H D D

①Firm w are LB A W rite data

PC B

②LB A

O riginal H ead

LBA

+

LBA'

HDD controller

O riginal D

isk

Write data

W rite data

S hadow D

isk

LB A '

Write data

S hadow H ead

1. HDD received "Target LBA + Write data" as Write command.
2. "Firmware + HDD controller" calculate LBA' which corresponding with "Target LBA" one-to-one.
3. "Write data" is written to disk as "Original data" at first using Original Head.
4. Same "Write data" is written to disk as "Shadow data" using Shadow Head.

This is the method of maintaining same data between "Original data" and "Shadow data".

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Automatical restoration function:

HDD read only "Original data" in principle for Read command from Host System. When HDD cannot read "Original data", automatic restoration function is performed useing with "Shadow data".

Autom atical re...