

Is Defragmentation (Defrag) Necessary?

Shaz writes:

Is defragmentation of drives necessary ? Please explain.

defrag hard drive folders

To understand why defragmentation (or defrag) is necessary, let’s go over how a hard drive stores files. Your hard drive is made up of sectors and blocks, which are like file folders and filing cabinets in an office. When a document, picture or other file wants to save to your hard drive the drive needs to find space to put it. To make most efficient use of the space on your hard drive (and allow you to easily delete/move files), the hard drive breaks up the files into little pieces and stores them where there is available space on the drive. The result of this is a file that may exist as a single, but pieces of it may be in 3 different parts of the hard drive. When you go to open the picture the hard drive knows to look in those 3 separate areas to get the complete file.

So why do you need to defragment if the hard drive knows where to look? Two reasons: Speed and wear-and-tear.

Speed: Every time the hard drive needs to move the read head to a new location it takes a certain amount of time to move. If the file is in one single area of the hard drive, the head only needs to move once to read the file. If the file is contained in 3 different places, the head needs to move 3 times to get the same file, making the time it takes to load longer.

Wear-and-tear: As a mechanical device, your hard drive read head moves a lot as it accesses files. Limiting the amount of times it has to move is going to increase the drives lifespan.


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