In the context of administering computer systems, defragmentation is a process that reduces the amount of fragmentation in file systems.

It does this by physically reorganizing the contents of the disk to store the pieces of each file close together and contiguously.

It also attempts to create larger regions of free space using compaction to impede the return of fragmentation.

Fragmentation occurs when the operating system cannot or will not allocate enough contiguous space to store a complete file as a unit, but instead puts parts of it in gaps between other files (usually those gaps exist because they formerly held a file that the operating system has subsequently deleted or because the operating system allocated excess space for the file in the first place).

Larger files and greater numbers of files also contribute to fragmentation and consequent performance loss.

Defragmentation attempts to alleviate these problems.

You can read here more about the Windows XP Defragmentation Tool

Regards

Marc Liron – Microsoft MVP

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