• Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint
Disk Defragmenter\windows\system32\dfrg.msc

Reorganize the files and pieces of files on a disk to optimize disk performance and reliability.

To Open

Start Programs Accessories System Tools Disk Defragmenter

Command Prompt dfrg.msc


As files on your hard disk are created, modified, and deleted, they become fragmented (so that a single file is physically stored on the disk surface in several noncontiguous pieces). As more files become fragmented, reliability and performance of the drive both diminish. Disk Defragmenter reorganizes the files and folders on any drive so that not only are the files stored contiguously, but free space is also contiguous (see Figure 4-24).

Figure 4-24. Disk Defragmenter rearranges the data on your hard disk for quicker, more reliable operations

Use of Disk Defragmenter is extremely simple. At the top of the window, you'll see a list of the hard drives installed on your system (on many systems, only one drive, c:, will be shown). Highlight a drive and click Defragment to begin the defragmentation process. Or, click Analyze to view a fragmentation report and a recommendation; note that Disk Defragmenter will claim that defragmentation is unnecessary if the percentage of fragmented files in the drive is lower than about 3 percent.

Note the map, signifying the files on your disk; refer to the legend of the bottom of the window for the meanings of the various colors. Defragmentation can take anywhere from 15 seconds to an hour, depending on the speed of your drive, the level of fragmentation, and the amount of data to move.


  • Disk Defragmenter is a "snap-in," a component used with the Microsoft Management Console (discussed later in this chapter). You can open it via its icon on the Start menu, by launching dfrg.msc, or by opening MMC and installing the Disk Defragmenter snap-in.

  • You can run other programs while Disk Defragmenter runs in the background, but this is not recommended for several reasons. Not only will writing to the disk interfere with Disk Defragmenter, causing it to restart repeatedly, but defragmenting a drive can slow system performance substantially.

  • With Scheduled Tasks, you can run Disk Defragmenter when you're away from your system (for example, every Sunday night).

See Also

Chkdsk, Scheduled Tasks

  • Creative Edge
  • Create BookmarkCreate Bookmark
  • Create Note or TagCreate Note or Tag
  • PrintPrint