Recovering data from a bad hard drive can
be simple, but don’t count on it.
All computer hard drives will fail. This is why they are only warranted for a couple of years. When hard drives fail the data on them is usually still there, but cannot be pulled off the drive for some reason. I will try to explain how to go about recovering data from a hard drive in these situations.
While this is a simplified version of how to recover data from a failed hard drive just to help you understand what is involved. it is NOT a definitive procedure for recovering data.
One of the ways that a hard drive can fail is for Windows to fail to boot, thereby trapping your information in such a way that you cannot get to it. When this happens simply repairing windows will probably make all your data available.
Another way you may loose data is because you deleted something, or formatted a hard drive that had something you need to recover. Data recovery software can often be used for this purpose, and many things can be recovered. Perhaps a different article someday.
However, this article will concern itself with recovering data when a hard drive is no longer able to be accessed by Windows.
Hard drives tend to fail because of one of these reasons:
The motor dies
The controller dies
The firmware becomes corrupted
The read -write heads become misaligned
The surface if the disk platters begin to degrade.
Mechanically, hard drives are not a really complicated device. Basically it is a metal case, with a motor mounted into the floor of it. This motor has a spindle on it similar to what your car has on its rear wheels. Instead of wheels and tires, this spindle has some small extremely thin discs, called platters attached. When the drive is turned on, the motor spins the disks. Above, in between, and below the platters there are little arms that travel across the surface of the disks using something called a read-write heads to read and write (get it?) little magnetic spots on the surface of the platter. Oh yeah, there is a magnet in there too.
All of this is controlled by a circuit board attached to the hard drive. This board has a small software program on it (referred to as firmware) that operates the hard drive. If you have an old hard drive, turn it over and look at where the cable connects to the drive. This connection is on the controller for the hard drive. If you touch any of the circuit board with your finger you can kill the drive by shorting the controller out with static electricity. Always handle a hard drive by the case, and take extreme care about static electricity.
When you send a hard drive to have the data recovered, the recovery company will hook it up and see if the hard drive will spin. If it will, then they will reload the firmware to the controller, and see if that works. If it doesn’t, they may replace the controller board with a known good part and see if that will work.
Sometimes, especially if the drive has been dropped, the drive case has to be opened, and the read-write heads have to be re-aligned or replaced in order to recover the data stored on the drive. When all else fails, or if the drive will not spin, the drive will be disassembled, a new drive of the same model is also disassembled, and the platters that have the lost data are installed into the new drive housing in order to recover the data.
If the surface of the platters has begun to degrade, the chances of loosing data skyrocket. Always backup your data, and never keep irreplaceable files on a hard drive more than 2 years old.
These complications mean that data recovery is a very expensive procedure to have done, and the results are unpredictable.