Do Mac hard drives need to be defragmented?

Hi Vixter

The theory is that OSX takes care of any defragmenting required as needed ... in practise I defragment my volumes every month or so using Drive Genius 3 (when it reports 20%+ fragmentation)

I also have external volumes I use for AHCHD files and editing, but in the example you give you can just delete the volume and then re-format it and that would take care of any previous fragmentation.

FWIW have you come across VoltaicHD from Shedworks, it's a handy utility for converting AVCHD files before editing in iMovie/FCP ? Not free but a very useful tool to have around - http://www.shedworx.com/voltaichd

for the most part, you should not need to defrag a mac os x hd. the mac os is pretty self-maintaining. you may find the following apple article a good read:

http://support.apple.com/kb/ht1375

In theory they self manage but in my experience, dealing with very large (AVCHD) files in particular, drives do become badly fragmented with write/delete/edit/move operations and there IS a performance impact without forcing de-fragmentation. In general I don't think users should do this but in some scenarios it can be beneficial.

Converting the files before 'ingesting' is faster basically, if you're going to output to QuickTime you could convert the raw files first, then edit, then output and I think you'd find it quite a bit faster. They offer a demo so try it out and see what you think.

For high bandwidth AV work, most people use a RAID so individual disk drive and filesystem performance aren't an issue. Fragmentation should only be a problem if your system is marginal for your application in the first place, and with a multitasking OS, it's pretty much a fact of life.

Defragmentation is dangerous for two reasons. If it gets interrupted, you're far worse off than when you began. And if there's a bad sector or corrupted data, it gets moved, possibly even propagated, but not repaired. If you must defrag run a full filesystem integrity check first.