When the substitution (Assign) mechanism is used in a drive the latter records to the ID field of a BAD sector the flag of the relocated sector and writes to the data field the number of the reserved sector, i.e. the one, which should be accessed for data recording or reading. As a rule, it is the first available sector after user data area. (figure 2.).
Figure 2. Method of rededicated sector.
During data read/write operations accessing the defective sector drive controller will read the flag and assigned address and reposition the heads to the reserved zone…
Firmware data is necessary for functioning of internal HDD circuits and as a rule it remains hidden from users.
Firmware data can be subdivided into the following types:
Servo information or servo fields;
Low-level format;
Resident firmware microcode (operational programs);
Configuration tables and settings;
Tables of defects.
Servo fields are necessary for operation of a servo system used by the driving assembly of magnetic heads in a HDD; they serve for heads’ positioning and keeping them precisely over a defined track. Servo fields are recorded during the manufacturing process to an already assembled…
Introduction
Brief architecture description, the main problems of modern hard disk drives, methods of HDD servicing and repair of simple malfunctions, SMART, passwords. The article is intended for data recovery specialists, technicians servicing computer equipment, network administrators and experienced users.
Drive construction
A drive consists of a mechanical part – head-and-disk assembly (HDA) and a printed circuit board (PCB). HDA acts as a case for all mechanical parts of a hard drive and contains one more chip performing the functions of a preamplifier/commutator. A PCB consists of several chips which control the mechanical parts, encode/decode data on magnetic surfaces and…
Random Notes and Ideas For Data Recovery
1. Drive goes to sleep, replace the board live
2. Partitions start on Cylinder Boundaries
3. Hard Drives have a Safe Mode
4. You can fix LaCie problems with a Mac mounting them in the system
5. Drives that you plug in that cause windows to Crash – Use Ubuntu to Read Files
6. When problems with MFT then retry smaller blocks
7. If drive parts are good then rewriting the SA area is the part that needs repairing
8. SA Code can be replaced to do data destruction or encryption
9. If
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Matching Serial Numbers on Hard Drives
This link is where I keep track of documentation on how each hard drive needs to be matched for a working donor drive. I get this any where I can, use it if you can, and if you happen to find something out please let me know so I can add it to the collection!
NOTES:
Drives with the same model number can still have different numbers of heads, therefore the board is different. It is possible to identify the number of heads in a drive: Maxtor,Quantum, Seagate from the serial numbers:
REFIRBUSHED…
Slide 4500: Doing a Platter Swap for a Single Platter
List of items needed:
The first step is to get a hard drive as close to identical as the bad drive you have that is a working drive. At the bottom of this paper you will find help about matching hard drives and serial numbers.
You need a clean area to work on with as little dust floating around as possible.
You will need about 1 hour to do this carefully
A screwdriver set with T3-T8. These are my favorite http://www.wihatools.com/200seri/278serie.htm
Post-it Notes
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Slide 4259: Head Replacement Section
This is the only section from last year I kept and it is because this is directly related to fixing this click of death problem.
NOTE: If there is only one platter it might be easier to move the platter than to move the assembly. You have to make that choice.
List of items needed:
The first step is to get a hard drive as close to identical as the bad drive you have that is a working drive. At the bottom of this paper you will find help about matching hard drives and…
Slide 3791: The cause of the click is from four possible areas, all resulting in the SA not being able to be read.
1. System Area of the drive cannot be read because the platter is scratched.
2. The head itself has a problem and cannot read the SA area.
3. Preamp on Actuator to the Head has gone bad and is not passing the correct signal to the electronics
4. The firmware on the board is damaged and does not initialize. This is sometimes caused by static electricity walking across the carpet to install the drives,…
Slide 2840: The GMR (giant magnetoresistive) head is the current head used on most hard drives. This head uses high end physics I do not claim to understand. The only major difference is the way the head has been changed to read perpendicular. The GMR head has four layers, a sensing layer, a conducting layer, a pinned layer and an exchange layer. It was discovered that if you took two magnetic layers and aligned them opposite each other with a soft layer between them that the magnetic force would align themselves in parallel. When a bit of data passes under…
Slide 2221: When the drive is manufactured it is known that there is going to be errors in every drive. Drives use ECC to correct most errors and if ECC can correct the error then the sector is never marked as bad. If it is marked as bad, the drive puts the data in a bad block list. Most people know that their hard drive has a bad block table. What most people do not know is that their drive has TWO bad block tables.
1. P-List (Primary Defects List – manufacture defect info that does not change)
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