disk defragmentation is tool to defragment the disk
To defragment a Windows 95/98/ME/XP/Vista/7 hard disk, use the Disk defragmentor program in Programs/Accessories/System Tools. On a Mac, use a utility such as the Speed Disk tool that comes with Norton Utilities for the Macintosh. You should defrag your hard disk every six months. You should also defrag it after you have created or deleted a lot of files in a short span of time.
Alternatively, you could download a free disk defragmenter program like asuslogics disk defrag . A very good, and very fast disk defrag utility.
Occasionally, a storage area called a sector on your hard disk goes bad. A utility called a disk scanner detects such "hard" errors and keeps a table of such sectors so that your operating system doesn't try to use them to store files. In addition, a disk scanner detects "soft" errors, where the operating system has lost track of pieces of one or more files. Scandisk (found in Programs/Accessories/System tools) is Windows 95/98/ME/XP/Vista/7 built-in disk scanner, and it detects both hard and soft errors. On the Mac, you can use the Disk First Aid program that comes with your system or the more powerful disk doctor utility included in the ubiquitous Norton Utilities for Macintosh. You should run a hard disk scan at least every month. In addition, if your computer crashes or you accidentally shut down without going through the proper shutdown procedure, run a disk scan as soon as you reboot.
