Originally posted by: Russwinters
Defragmenting a hard drive will make a large difference if you are constantly adding and removing programs and files from your computer.
The reason is that when you delete small things like mp3s, and pictures it leaves small little spaces in between your other larger files.
When you go to install a new game, it will actually fill the gaps with some of the data from that game, and so now you hard drive has to perform whats called "Butterfly operations" to get to those sectors.
Butterfly operations are when the hard drive is working its hardest, where it has to fly much further physically to read files that are fragmented all over the disk surface. Not only does the reduce the performance greatly due to the fact that games primarily utilize random seek operations; the further the heads must travel from sector to sector the longer it is going to take to read all the sectors needed to give you that file. If all of the files are in physical close proximity of each other this will reduce your random accesstime thus improving your gaming and application performance.
To make things worse, a drive the is constantly performing heavy butterfly operations is at higher risk of failures such as a head crash. A head crash is when the heads actually physically crash into the disk surface, causing damage to both the heads, and the sectors in the crash zone. The manufacturers have plenty of safeguards that try to help, but most of them fall short of really doing any good.
So there you have it, defrag often everyone!
Phew. thats a mouth full.