The hard disk is made very like a record player. It is comprised of round, polished platters, which are made up of aluminium alloy. Typically, a hard disk measures between 3.5 inches or 5.2 inches in diameter. Most consumer drives use a single platter but there are those that use two or four stacked platters. The platters are further divided into tracks. These tracks run in concentric circles which are further divided into sectors. These sectors help the hard drive to locate information easily.

Several things can go wrong with a hard disk and a head crash is a specific type of hard disk failure. A head crash occurs when the read-write head of a hard disk drive touches a rotating platter. This leads to damage of the magnetic media on the surface of the platter, which can be catastrophic.

The head rides on a thin film of moving air. This air is trapped at the surface of the platter. A Teflon-like material, which acts like a lubricant, makes up the topmost layer of the platter. The layer underneath, is made up of sputtered carbon. These two layers protect the magnetic layer which stores data, from most accidental touches of the read-write head.

The tiniest particle of dirt can cause the head to bounce against the disk, which will destroy the thin magnetic coating on the disk. The read-write head is hard enough to scratch through the protective layers.

Most modern drives spin at rates between 5,000 and 15,000 rpm which is why when damage is caused due to a head crash, it can be extensive. The edge of the platter travels at over 74 miles per hour. When a head crash occurs, it drags over the platter surface, the read-write head generally overheats. This makes the drive unusable until such time that it cools.

If a user continues trying to use the drive, particles of material can increase the chance of further head crashes. This can lead to extensive data loss and will be very difficult to retrieve.

When a head crash occurs, a strange noise might emit from the computer and the screen may go blank. The average user might panic and try to restart the computer and worsen the situation. The best thing to do when there are obvious signs of a head crash is nothing. A head crash requires the intervention of experts to prevent permanent data loss.

Data recovery experts will take the hard drive off-site to a Clean Room and through a painstaking process, retrieve the data that has been lost.

Considering that head crashes can happen without too much provocation, it is extremely important for users to take regular backup of data. Regular backup ensures that a user will not suffer data loss and work can go on as usual. The market is flooded with various backup media options -- from floppies, CDs, DVDs, flash drives to remote or online backup options.

It is important to make backup a regular routine, as one cannot tell when a disk might fail. If backup is not taken seriously, the resulting data loss from a head crash can lead to serious consequences.

It is important that a hard drive is kept in a clean and dust-free environment to maximise its longevity. Extreme temperature fluctuations or great heat can also lead to things going wrong with the hard drive. Therefore, it is important where a computer is kept. A hard drive comes with a definite shelf life of about three years, after which it behaves in an erratic manner.

While it might be tempting to try cheaper DIY methods of data recovery, a hard disk is a serious problem and requires an expert. Therefore, it is important not to meddle with the hard disk when the head crashes.

A head crash is problematic but does not cause irreversible damage. It is advisable for computer users to make themselves aware of the problems that can arise with a hard disk. This will help them deal with a problem and to be always prepared. As long as one is prepared, the world of information technology is extremely user-friendly.