What is Hard Drive Defragmenting?

What is hard drive defragmenting and why does it improve my computers performance?

Mick, New Lambton Heights

Hi Mick,

Before we explain what defragmenting your hard drive is we need to explain a little about how a hard drive stores your data. In this case we are talking about a traditional rotating media hard drive not the newer SSD (Solid State Drive). You should never defragment a solid state drive they work differently, and defragmenting them will lower their life.

When describing a hard drive to someone we often use the analogy of a record player. There is a platter or record that has the data (or music) on it and a head that moves across it to read the data (or music).

Over time as you add and delete files, gaps of free space are left on the drive where a file that existed has since been deleted. The hard drive is smart though and will use these gaps to put more data in. The issue of fragmentation is created when the hard drive goes to use the free gap however the file it wishes to save is bigger than the gap.

This is no issue for the hard drive. It simply saves what it can in the gap then puts what remains of the file elsewhere.

While a smart use of free space, it does create the issue that you have files scattered all over the place. When the hard drive goes to read a file that is scattered it has to move the head to each piece of the file. This process takes time and slows your computer down.

Defragmenting is a process that rearranges the files on the disk to reduce the amount of files that are scattered (fragmented). By doing this, when accessing files the hard drive head doesn’t have to move as often increasing your computers performance.

Most modern operating systems attempt to be smarter about how files are stored to reduce fragmentation of files however they still need to be defragmented every now and then. Windows for instance will automatically defragment your drive weekly.