File fragmentation and OS X

Disk fragmentation is a common problem for anyone who’s worked with Windows, but what about fragmentation under Mac OS X? The Apple Blog’s Andrew Bednars examines the problem and also takes a look at several solutions on currently available on the market.

Fragmentation occurs when the pieces data that make up a file are written to different locations on a disk, rather than all together. This can slow down disk read or write operations because the operating system must search different parts of the disk for information instead of finding it all in one place. Mac OS X ordinarily tries to minimize disk fragmentation as much as possible. Whenever a file under 20MB is opened, the OS checks to see if the file is significantly fragmented. If so, the computer attempts to consolidate all the pieces together in one place. As Bednars points out in his article, this helps minimize file fragmentation, but doesn’t help keep free space from being broken up.

Bednars shows a few terminal commands that can help you determine if your Mac’s files are fragmented or not. He then show what to do to help. Since the OS doesn’t come with a file defragmenting tool (unlike Windows, which features one many users run with ritualistic fervor), Bednarz examines three pieces of commercial software ranging in price from $30 to $99.

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