Paper has never been a reliable means of storing data. At this moment, most people believe that storing data in hard disks is the most secure way of maintaining all data that is precious to them. And this is where there are a lot of misconceptions and myths that are doing the rounds among computer users.
Contrary to popular belief, a hard disk will not last for generations. No manufacturer is willing to rate the life expectancy of an average hard disk beyond three to five years yet. Of course, the disk lasts longer in most cases, but this is more a matter of good maintenance, chance factors and awareness on what causes hard disk failure.
Broadly speaking, there are two ways in which a hard disk can lose data through hardware (physical) problems or through software (logical) problems. In the first case, the disk itself is directly damaged, but the data in it may remain unharmed. In the latter case, the data has either been corrupted or deleted, but the hard disk may be physically intact. We will be looking at these causes in greater detail in the following.
Hardware Errors
A hard disk may be physically harmed in these ways:
Fire, water, dust, impact no hard disk will survive calamities. Though the latest disks are much more resilient than ever before, there is a temperature above which the metal component will simply melt. However, professional recovery people have always tried to work miracles, and data has been recovered from shipwrecked and fried disks too. Dust is very bad for the disk avoid taking out the disk from its casing, if you do, you will be digging the grave for your own data. Impacts will lift data off the disk if the vertical component of the drop is greater than the rate at which the disk is rotating, i.e. the data will literally fly off the falling computer. Scratches on the surface of the disk will, again, be enough to kill it. Humidity and direct sunlight are also bad for it.
Data will be deleted from the hard disk if it gets electrocuted in any way through an electrostatic discharge; or if there is a power surge or spikes that burn through the circuitry on the board.
Sometimes, the hard disk itself may not be affected, but the read or write head on it may collapse. This means that effectively the data is out of your reach till the malfunctioning part is replaced.
Forced shutdowns or switching off power while the computer is running will delete all unsaved data and may damage the disk also.
Logical Causes
Virus Attack: This is the most well-known causes of hard disk crash, though it is not the most common reason why crashes happen. A virus is a programme written with the malicious intent of deleting or corrupting other files. The virus, once it gets into a system, replicates itself over and over again, filling the disk and deleting data and applications from it. Some virus can attack a certain format, for example, jpeg, and corrupt all files of that format. This in turn will affect other applications and, ultimately, the computer will come to a standstill. Viruses are a fascinating study matter, and would need a separate article even for a brief introduction. There are viruses that come in through the internet, some that affect floppies, some that attack OS, some specializing in media files and, of course, the innocent email attachments.
OS Crash: Though all companies claim the OS to be infallible, they are not so. The Operating System will take all documents with it that were stored in it, such as the offline inbox, personal settings, details and addresses of sites visited, etc. All users are strongly advised to keep a backup of important data in another partition away from the one in which the OS programme files are housed.
Fragmentation, Overwriting, and Corruption of Files: There are some folders, such as the mail inboxes, that we keep updating on and offline. So these file name ends that trail on and on reflecting each update made become very easily corrupted. As the bad sectors thus formed increase in volume, the files get more and more fragmented, i.e., they are stored under various addresses scattered all over the disk. Finally, they become unreadable.
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