There is only one storage device that fits the bill ? the hard disk. Indeed, hard disks have been the primary data storage media of computers since the latter got invented. Even today, there is no competitor on the horizon that can challenge their monopoly.

How Hard Disks Work

Computer hard disks are quite small, not much bigger than the palm of your hand. They are heavy because their outer covering and inside components are mostly made of metal. The disks come in the shape of a rectangular box which can be screwed securely inside the computer CPU. Their rear side has ports from where a data cable connects to the motherboard while a power cable feeds electricity from the SMPS.

Inside the hard disk, the most crucial component is a series of platters stacked vertically that is mounted on a single spindle motor. The surface of these platters is thinly coated with magnetic paint and is the area where the data actually gets stored. When the hard disk is switched on, the platters begin to be spun by the motor at a very high speed, from 5,400 RMP to 7,200 RPM.

Above the platter surface, at a sub-micron height, floats the actuator arm, on the tip of which is located a read / write head that carries an electro-magnet. It is this head that actually accesses and modifies the data as it is moved around over the platter surface by the arm.

The higher the capacity of a hard disk, the more platters it will have, with a separate read / write head for each. When the user switches off the computer, the operating system first ensures that the actuator arm moves over to a side and comes to rest in its parking bay.

The electricity supply to the disk is controlled by a circuit board while the operating system communicates with it through a controller card.

Portable Hard Disks

Hard disks offer phenomenal functionality and data-holding capacity compared to their low price and small size. However, the problem is that the disks installed inside computers or laptops are not removable, which is a big issue if you have to transport a huge amount of data from one place to another or create its backup. This need was fulfilled by making hard disks portable and removable.

Portable hard disks are nothing but ordinary computer hard disks that are enclosed in a tough casing that can take some amount of abuse. These are independent and stand-alone devices that can be connected to any computer or laptop through a USB cable. Portable disks come with a backup software that automatically takes backups of individual files or creates a mirror image of the entire hard disk.

How Data can Get Lost

Hard disk manufacturers strive to make their products as tough as possible. Still, it is a fact of life that these disks keep failing. They have a number of complex mechanical and electrical components that have a life of a fixed number of years. Regardless of how well-maintained they are, sooner or later something is bound to give. A user can experience hard-drive-related data loss due to a number of hardware or software causes.

Perhaps the most dreaded word for a computer user is ?hard disk crash.? This is a very serious situation that makes the entire data on the hard drive inaccessible. A crash occurs when the actuator arm becomes unhinged and falls flat on the platter surface.

When the user switches on the computer, the platters start spinning and the read / write head begins to scratch their surface. This results in permanent damage since it is almost impossible to recover data from a recording surface that has been furrowed. Some other comparatively benign causes of a hard disk going dead are the failure of the spindle motor and a malfunction of controller card or circuit board.

Data residing on a hard disk can be lost due to software errors too. A virus attack may corrupt the file and make it inaccessible. The user may delete data accidentally or reformat the entire disk, thus wiping out all files that existed on it.

While most cases of data loss due to software errors can be easily tackled by commercially available DIY recover software, for hardware errors there is option but to take the hard disk to a professional recovery company.