The simple mother hard disk drive continues to reside within the four walls of the computer, even today, while her offspring (whose features are no different from her), have clothed themselves in sleek , colourful and customised outfits to take on the world of data. Like her, her offspring come in three different sizes -- 1.8 inches, 2.5 inches and 3.5 inches. The big heavyweights of traditional hard disk drive manufacturing (Seagate, Samsung, Western Digital, Iomega etc.) logically dominate the external hard drive market space, because of their established infrastructure and long exposure.

External hard drives offer a distinct safety advantage. Unlike the hard disk drive, these portable giants are not sitting ducks, waiting to get hurt by online threats, hardware malfunction of the computer or multiple abuse of the same computer by varying degrees of human handling. They can be connected to your computer and not suffer any of these problems unless you store potentially harmful data onto the external hard drive or the hard drive is rudely handled.

Regularly update the external hard drive and it will reflect a clear carbon copy of the data and data structures residing in the hard disk drive of your computer i.e. an exact twin of your hard disk drive (inclusive of the operating system). Your data security will not be compromised, in the event of a data loss suffered by the hard disk drive. Take sufficient care to ensure that you do not replicate the garbage on your hard disk drive onto the external hard drive!

At mind-numbing data transfer speeds of 480 megabytes per second (and second to none), your stylish external hard drive can store up to 2 terabytes of data (that’s a 1 followed by 12 zeroes or almost 3% of the data available in the U.S Library of Congress). Tape drives are the closest competitors to external hard drives, but cannot match the external hard drive in terms of data transfer speeds. Average cost per gigabyte, for an external hard drive, varies between $0.30 and $0.88. The tape drive (LTO-3) sets a benchmark cost of $0.25 per gigabyte.

You are a music buff, an avid movie collector and you also firmly believe in the policy of not mixing work with leisure. So does the Company policy. Therefore, allotting space for the latest hits or movie releases, in your computer’s hard disk drive is taboo. During the lunch break, you prefer to unwind by listening to your brand of music. That’s absolutely possible, thanks to the USB 2.0 / Firewire connectivity of external hard drives. You can load your entertainment from the external hard drive by simply plugging it into your computer’s USB port and invoking the media player. All in a couple of seconds, without endangering the computer or the external hard drive. You can also restrict access to confidential data by storing them separately on an external hard drive and additionally enabling the passwords on it too.

Capable of being carried in your shirt pocket, external hard drives offer the additional advantage of portability, over the traditional hard disk drive. (James Bond - From Russia with Love - discovered that the metal cigarette case in his shirt pocket could stop a bullet. That’s an added security bonus!). Take it anywhere in the world and plug it into a working USB port. It works. Your virus-infected external hard drive, however, could be a tool for unknowingly introducing new forms of malware in hitherto uninfected parts of the world, by your action of plugging into USB ports, halfway across the world. Beware.

Some users tend to bunch multiple external hard drives, in order to obtain a single virtual hard drive of combined capacity (representing the multiple disks). For example, combining 4 external hard drives of 100 gigabyte storage capacity into a single virtual external drive of 400 gigabytes! However, if you have the money, it’s easier to buy a single 500 gigabyte external hard drive, off the shelf, though!

Just as how all good things have to come to an end, there isn’t much you can do for your music collection, on the external hard drive, if you subject it to severe jolts and physical impacts. Care for it and you can keep your data looking good for 15 years. Letting water into your external hard drive mostly means that your data’s out, permanently. Hardware malfunction, by the external hard drive components (like the fan inside the case), can be irritating and harm your data, though not so seriously. Crashing of the read write heads onto the disk’s data storage surface or failed internal motors could result in data loss ranging from the minimal to severe. Remember that the external hard drive is every bit as sophisticated as your hard disk drive. So in case of data loss, do no further harm. Rush the victim safely to the data retrieval experts.