So what has happened to my hard drive?

Whilst it can very very difficult to diagnose a hard drive failure without data recovery tools, there are some tell tale indicators to determine the likely issue. Take a look below to see if your hard drive is exhibiting any of these symptoms.

Logical Hard Drive Failure

Hard drive recognised by BIOS, but cannot be accessed

In most cases, logical failure is when the computer’s BIOS can see your hard drive, but for some reason can not access the data on it. It may not be able to mount the partition or may simply report that no drive is present at all. In the most extreme cases logical failure can include a hard drive that spins up fine, but is not even recognized by the computer’s BIOS as being present.

In a logical failure the hard drives electronic components and mechanical components are all working properly. Logical failures occur as a result of defective media (platter degradation) or data corruption from another source (destroyed file table, etc…)

Almost all logical failures can be recovered without the need to open the hard drive. While there are a number of logical data recover software programs on the market, its important to know why your drive has experienced a logical failure before you attempt to recover your data. If you misdiagnose a logical failure, you can cause irreparable damage to the drive in your recovery attempt.
Mechanical Hard Drive Failure

Hard drive making clicking or ticking noises

Clicking sound in hard drives signal a disk drive has failed, often catastrophically. The clicking sound itself arises from the unexpected movement of the hard drive's read-write actuator. At startup, and during use, the disk head must move correctly and be able to confirm it is correctly tracking data on the disk. If the head fails to move as expected or upon moving cannot track the disk surface correctly, the disk controller may attempt to recover from the error by returning the head to its home position and then retrying, at times causing an audible "click".

In some devices, the process automatically retries causing a repeated clicking sound. Assuming there is no corresponding damage to the hard drive platters, we can recover the data by opening the hard drive in our clean room and replacing the heads.
Circuit Board Failure

Drive not recognised and appears dead

When it comes to data recovery one of the most common problems hard drives experience is burnt cuircuit boards (PCB). Hard drives are very vulnerable to overheating, power surges and streaks. Quite often a bad power supply unit combined with power streak is enough to fry the spindle driver chip on the electronics and make the data inaccessible.

Swapping the PCB from another hard drive of the same model can occasionally work on older models. The problem is that logic board on a modern hard drive is adapted to the head disk assembly it was manufactured with. In our lab we use specialized software and hardware to rebuild these parameters or transfer them from fried board to make donor PCB fully compatible with damaged drive.
Hard Drive Bearing Failure

Hard drive grinds on startup or doesn't spin

Grinding or screeching noises might mean the bearings or spindle motor are failing. This is one of the worst type of hard drivce failures as our technicians must remove the complete platter and head assembly to replace the motor or re-lubricate bearings. These failures can be as a direct result of the strain placed on the spindle motor by the weight of the platter, or sometimes an impact will also cause this type of failure.
Mechanical Hard Drive Failure

Hard drive spins then shuts down very quickly

Just about anything could be wrong with a hard drive that is shutting down after a few seconds. Most hard drives will shutdown when they detect a severe error to try to prevent further damage. The controller board could be bad, and swapping it with an identical one may solve the problem. For some drives, it doesn't need to be just the same model - it needs to be the same revision and firmware level as well.

The spindle motor could be seized or partially seized causing it to draw more power than it should and shutting down. Similarly the heads could be stuck or damaged. Regardless, the only way to recover the data is to open the chassis in the clean room and inspect the damage.