How to recover system's data ?

One function of the system area is to log defective sectors within the drive; essentially telling the drive where it can and cannot write data.

The sector lists are also stored on various chips attached to the PCB

And they are unique to each hard disk drive

If the data on the PCB do not match what is stored on the platter,

Then the drive will not calibrate properly

Then the drive will not calibrate properly

Then the drive will not calibrate properly

In most cases the drive heads will click because they are unable

To find the data matching what is stored on the PCB.

In some cases, data on a hard disk drive can be unreadable

In some cases, data on a hard disk drive can be unreadable