Fragmented files are files whose contents are split up into chunks, and stored in various locations across their storage volume. Fragmentation occurs over time as the files on a disk are added, deleted and modified.
The most efficient way to store files on disk is in a contiguous manner, meaning each piece of the file is adjacent to another. In order to access the file, the disk can seek to the location of the first piece, and read straight through to the last.
Fig. 1 - Three contiguous files, each indicated by a different color.
As a disk adds, modifies, and removes files, small gaps appear where old data used to live. If a new file is created, or an existing one must be modified, and its contents cannot be stored contiguously, the operating system will fragment the file into chunks and use them to fill in those gaps.
Fig. 2 - Three fragmented files, each indicated by a different color.
Reading a fragmented file requires more time and effort on the part of your computer. When a fragmented file is requested, the hard drive must seek to the different locations of each individual file fragment in order to read its entire contents.
Severe defragmentation can cause a number of problems for a computer system. A computer with a fragmented storage volume may encounter errors, latency in read/write operations, and even (possibly) suffer from data loss.
Who should defragment?
Advances in operating systems and the increase of low-cost storage capacity continue to make it less and less necessary for the average computer user to defragment their hard drive. Mac OS X automatically optimizes disk usage, and Apple claims that most people will never need to defragment. The extent to which this point is true is debateable.
Regardless of which operating system they use, certain people, such as those who work with large files, e.g. audio and video, and those who tend to exhaust storage capacity quickly, may very well benefit from defragmentation.
How to defragment
Microsoft Windows includes a programmed called “defrag”. You can access defrag via:
- Start
- Run
- Type “cmd” and press “OK”.
- Enter “defrag” at the command prompt.
Mac OS X users who wish to defragment must use third party applications. They should check out this useful article on defragmentation from Paul Stamatiou, and consider purchasing iDefrag from Coriolis Systems.
