Why Defragment?


It has often been asserted that defragmentation (or disk optimization) is not a good idea on systems using Apple’s HFS+ file system. The main reasons given for this historically have been:

Whilst these arguments are certainly valid, they are not the whole story. For one thing, iDefrag, unlike most other disk defragmentation tools, fully supports the most recent features of HFS+, namely the metadata zone (or “hot band”) and the adaptive hot file clustering support added in Mac OS X 10.3. Not only does it avoid disrupting them, but it is capable of fixing disruption caused by other software by moving files into or out of the metadata zone as appropriate.

Sensible arguments for occasional optimization of your disk include:

We do not recommend very frequent optimization of your disk; optimizing a disk can take a substantial amount of time, particularly with larger disks, far outweighing the benefits that are likely to be obtained by (say) a weekly optimization regime.

Optimization may make more sense, however, following large software updates, or on an occasional basis if you notice decreased performance and lots of hard disk seeking on system start-up or when starting an application.