Causes of data corruption

Computers are very fickle machines, as we all know, they can be sturdy and reliable in the most trying times. You can drop them and kick them and spill coffee all over them and they won’t be fazed at all and one day an ant will crawl on top of it, there will be a click, a buzz and your screen will beat a hasty retreat. The causes of data corruption are rich and varied, it could be all the kicking and the dropping and the coffee spilling, or it could be any one of the following:

Bad exits from Windows. There are several conditions under which this occurs e.g. if the user switches the computer off or resets it without shutting down properly, if the shutdown process fails in some way, if there is a power cut and the computer resets on its own or if the computer freezes or locks up so that shutdown is impossible. This type of crash is usually in accordance with sane file management; therefore the only data corruption observed will be the interruption of sane file operations. The only damage visible should be incorrect free space count, lost cluster chains and possible incorrect file lengths.

Hard drive disk defects. Hard drive failure comes in various guises: 1) sudden catastrophic failure, which occurs when a drive can no longer be seen by its operating system. This kind of failure requires clean-room facilities and expert know how in order to repair it. 2) Head crash – heads touching and damaging the surface of the disk 3) pollution of the air inside the sealed drive unit 4) general surface wear often goes hand in hand with pollution of the sealed air inside the drive unit. It could be that the air filters malfunction or seal up or it could be that the unit was opened; perhaps debris was spread during a head crash. Whatever the reason, dirt has got into the unit and is wearing on the disk. 5) Spurious bad sectors.

Another hard disk defect is gradual disk failure. When a certain sector in your computer becomes unreadable its contents are copied to a spare sector (one of many that your computer has) and retains its physical sector address. This process is completed before the sector has failed completely. Once the sector can no longer be read then it is possible that silent data loss can occur. Only when all the spare sectors have been used up or when a defect is too severe to be repaired, all of the bad sectors will become visible to diagnostics. It is therefore preferable to replace the first bad sector while it is still under warranty.

Other flaky hardware. If something is capable of corrupting the data in RAM, it is capable of corrupting the hard drive contents. Examples of this include: 1) bad RAM 2) bad processor fan 3) over-clocked PCI bus 4) Data cables that are too long or too old or generally in a bad condition 5) overheated or poorly grounded hard drive 6) flaky motherboard, hard drive controller and processor. Failures of theses kinds can result in corrupting what is written to the disk as well as corrupting where things are written to the disk. Neither of these is particularly good news to a computer owner.

It is recommended to try and prevent the pain and hassle of hard drive corruption by running a disk defragmenter every 3 months to keep it in good condition. In addition to this you should try to move your computer as seldom as possible. If you have to move it, it is best to repack it in its original packing materials to protect it during the move. Remember to back up your data on a regular basis and lastly, and very importantly, don’t drop it.
Recommended sites:
http://users.iafrica.com/c/cq/cquirke/baddata.htm
http://www.kobaltcomputers.co.uk/acatalog/faqs_diskdrives.htm