Head crashes are the most common form of lost data on a hard drive. If a loud screeching noise is heard from the computer and access is lost, then almost certainly a head crash has been experienced on the hard drive. There are other circumstances that can cause a similar noise but will not necessarily result in the user being locked out of their computer. A failure of the fan which cools the devices may also cause a screeching noise if a moving part within the fan fails.

There are several moving parts within a hard drive. Magnetic coated disks or platters store the data and read/write heads float on a cushion of air a few micro meters above the surface of these disks. Rotating at speeds of typically 10,000RPM, these heads pivot over the surface of the disks.

Hard disks are manufactured in clean rooms, which ensures that debris or dust within the drive is kept to a minmum. In addition to this, the parts are cleaned in ultrasonic baths to ensure no unwanted grease or contamination is present during assembly.

These essential precautions are necessary during manufacture as any particle of debris no matter how small can get trapped between the head and rotating platter, causing the head to hit the surface of the rotating disk. The head will cause more debris to be scraped off the surface of the disk, resulting in the head digging into the disk surface and causing a head crash. This is the screeching noise that you hear.

Sometimes a very low clicking noise may be heard which may indicate that a major head crash is pending. If this sound is heard immediately turn off the computer and seek advice before a more serious head crash occurs.

There are several causes of head crashes. If the drive is reaching its end of life, partials wear off some of the moving parts. On a well designed and manufactured drive, this may take many years. Often drives will continue to function for well for over 10 years.

If the drive has been badly treated by excessive temperature fluctuation, perhaps located close to a radiator, boiler, or air conditioning unit - this will cause excessive expansion and contraction of the delicate parts within the drive causing a premature failure. Mechanical shock such as dropping the drive of placing it near large vibrating machinery will also disturb these delicate rotating parts again causing the heads to dig into the surface of the disks.

Strong magnetic fields from large motors and generators, permanent magnets and even medical and industrial scanner such as MRI scanners used in hospitals will also influence the magnetic parts within the drive. These external strong magnetic fields may also disturb the magnetic partials coated on the surface of the disks thus resulting in data loss.

Although the hard drive is sealed during manufacture for dust and debris ingress, any contamination which is sucked into the computer enclosure will slowly block up the airways which keep the computer and hard drive operating at the correct temperature.

It is important that all of the above is understood by the person who installs the computer as well as the users so that they ensure that it is positioned in a suitable location away from vibration, fluctuations in temperature, shock, strong magnetic fields and dust contamination.

If data is lost from a head crash or any other hard drive failure all is not lost. Once a head crash is suspected immediately switch off the computer and seek advice from a professional data recovery company. Data Recovery Specialists Ltd. have an enviable record of recovering data from hard drive crashes.