I decided to defrag my computer for the first time in many months. After about an hour it's complete. I don't notice any difference in my computers performance...not that it was running slow or bad in the first place. My question: why defrag? What purpose does it serve? How often should it be done?
to clean up the pockets of space on your hard disks as you install/uninstall/create/delete files and programs. This way the arm on the hard disk doesn't have to move so much to access data because defrag moves data around so that it is stored in sequential sectors. its basic optimization.
It's like dumping all your file cabinets onto the floor, and sorting out your papers in alphabetical order so that the next time you use your cabinet, everything is so much easier to find. I had an instructor who didn't believe in defraging. He thought the benefits of a faster drive didn't outweigh the wear the hard drive was taking in sorting out all that crap (the head would have to search constantly while placing the data out of place and then into order). He recommended making a ghost image of the computer (like after installation) instead and then running that when your disk was cluttered.
It helps if your disk was more than 5% fragmented. Otherwise you're just wasting a lot of time. (unless you like to watch the little squares )
Using Windows defragger? I've seen that happen before, it was caused by having background programs running at the same time...the defrag process would get interrupted and have to start over. Defragging only changes the speed of hard disk access when it is over 15-20% fragmented. Its nice to do from time to time if you install and uninstall programs alot...or create and delete alot of files..otherwise, dont bother doing it more than once every other month or so. as for the reasons why to do it...drapg and IFan explained it as well as can be put into non-technical terms.