8: Disk fragmentation

As files are added, deleted, and changed on a disk, the contents of the file can become spread across sectors located in disparate regions of the disk. This is file fragmentation. All Windows operating systems subsequent to Windows NT have built-in disk defragmentation tools, but there are also third -party programs available that give you more options.

If you have traditional hard disks, disk fragmentation can significantly slow down your machine. The disk heads must move back and forth while seeking all the fragments of a file. A common cause of disk fragmentation is a disk that is too full. You should keep 20 percent to 25 percent of your hard disk space free to minimize file fragmentation and to improve the defragmenter’s ability to defrag the disk. So if a disk is too full, move some files off the drive and restart the defragmenter.

Note that SSDs work differently and can access any location on the drive in essentially the same amount of time. Thus, they don’t need to be defragmented.