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General Data Recovery Knowledges

February 21st, 2013

1. The Frequently Reasons of Data Lose

a) Logically:

Delete;
Format;Virus;
Be Protected;
Partition tab or MBR/DBR Broken;

b) Firmware:

Management Modules:Hard Disk couldn’t work or work well;
Data Modules:Data lose or disordered;

c) Physically:

PCB Problem(Print circuit board. Donor PCB can be found on HDDZone.com);
Bad Sector;
Motor Broken;
Platter Scratch or out of alignment;
Head Broken or out of alignment;
Hard Disk over heated;
Other Reasons;

2. Hard Disk Defect Classification

Hard Disk Defect sector
Defect sector is the main defect in Hard Disk , it means the sectors couldn’t be read.
-ECC (error correct code) Error: Every Hard Disk write a data to a sector, it will produce a ECC code. The next time read this sector, the OS will compare the ECC, if it is not correct, it would show error sector.
-Sector ID / Address mark not found.

Reason:

Storage medium damage (scratch);
Magnetic reduce (Frequently R/W);
Head problem / OS problem;

Servo Track Defect
Every track has one or some servo info, for head seek position and recognize the right track.
If one servo has problem, this track couldn’t be read.
Represent:Couldn’t partition / Format / even scan

3 Impossible Scope of Data Recovery

a) Logical problem

Data has been overwritten or zerofill

b) Firmware problem

Key modules corrupt but couldn’t find the donor FW;
P-list was broken and no backup file;

c) Physical problem

Strong scratch;
Platter overhead or break;
Head or PCB broken and no donor material;

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