Electrical/Electronic Failure

The printed circuit board (PCB) of a hard drive controls and coordinates the communication between the computer and the hard drive in order to read and write data. So, when it gets damaged (mostly due to surges or power spikes) you lose access to your data. More often than not other hard drive components are affected as well such as the read-write heads and pre-amplified circuit.

Signs of electrical/electronic failure are:

• Drive is powered, but shows as if not functioning (platters not spinning)
• Disk knocking as the motor fails to spin
• Repeated clicking sound as the heads search or initialize

Mechanical Failure

Mechanical damage usually comes as a result of impact (fall, hit) or wear and tear. All internal components, such as the read-write heads and the motor can fail without prior warning.

Signs of mechanical failure are:

• Clicking and grinding sound
• Platter not spinning due to motor failure
• High pitched noise resembling music tone as the drive is powered up.

Firmware Failure

Firmware is the software used to do low level disk testing and

Firmware is the software program normally only accessible by the disk manufacturers. It is used to do low level disk testing and functions that are directly responsible for the proper functions and healthy state of hard disk. Most hard drives have their firmware code on the data platters and the PCB.

Signs of firmware failure are:

• Drive powers up, but is not recognised in BIOS
• Drive powers up, but is recognised in BIOS with a wrong or not understandable name
• Drive freezes during boot time

Bad Sectors

These are data blocks or sectors that cannot be accessed for reading or writing. This can be caused by wear and tear of platter surface, head crash, manufacturing defects and tracking errors. The severity of a drive having bad sectors varies widely.

Signs of bad sectors are:

• Drive can be accessed but it is very sluggish
• Continuous CRC errors
• Unable to access files or folders that could be accessed before

Logical Failure

Refers to non-psysical failure, such as accidental deletion of files or drive format, file corruption, viruses, file system corruption and more.

Combined Failure

Quite often the failure is caused by a combination of failure modes , usually one causing the other. For example, a read write head crash due to mechanical failure could cause logical file system damage.