As the question suggests, does anybody have any tips in increasing disk performance in OS X Leopard?


Defraging (you'll need a third party app such as iDefrag) may make a difference in specific instances (specifically if you're running at more than 90% capacity or use particularly big files):


Some apps (such as iDefrag) also offer disk optimisation and this MacFix article suggests that they may be right getting some performance improvements on a machine that didn't meet the apple criteria:


I can't personally vouch for it but I am interested and may look at buying it when I've got some spare cash knocking around.

  • I have been thinking of purchasing iDefrag, I think i might... thanks for the answer... – Alexis Hirst Jul 22 '09 at 22:18
  • I use iDefrag and while it can take forever to do a full optimization (using a Boot DVD), it does make things snappier for a bit if you maxing out your HD. – Darren Newton Jul 23 '09 at 19:33
  • Note iDefrag 2 is coming out shortly, you may wish 'till they release it. – alimack Feb 21 '10 at 11:19

iDefrag is very good and respects the 'Hot Zone' for the Mac OS, check the existing directory structure first using Disk Utility, repair it if it's showing any problems - use DiskWarrior if DU fails. You can also check out Tech Tools Pro and Drive Genius.

Also utilities such as Cocktail and Onyx are good for clearing out general rubbish on the drive. Grand perspective can give you a look at the drive and all the cruft you've accumulated.


This is probably a bit beside the question, but the best thing I ever did to boost disk performance on my Mac was to buy an SSD. Expensive but extremely rewarding results.

  • I bought myself an SSD recently, and it is quite possibly the best upgrade i have ever bought… Never again will I go back to using hard disks… – Alexis Hirst Feb 11 '10 at 11:23

A very simple solution: clone your drive using CarbonCopyCloner and then restore it - it makes files contiguous, and you get a backup in the process!!! :-)

Here is a whitepaper from the Superduper! guys (a great commercial alternative to CCC) on this type of defragmentation:


I have tried iDefrag, and it does what it says on the tin, very nice UI and the best defrag software for OS X by far (hot file aware for example which many others aren't). I've also tried Disk defrag, which is part of Speed tools, which does very basic defragging but doesn't require a roboot which is good.


I would not recommend defragging as this can actually reduce performance on OSX, especially if it will move the hot area of the drive (system files usually in the fastest area of the disk).

The journaling implementation of HFS will copy files on write, it's advised that if you have data that is less important then you should create separate non-journaled volumes and mount those individually. Temp area is a candidate for a non journaled partition.

Also if you're storing a database on your volumes then you want to turn journalling off as they usually have an BI (Before-Image) associated which is effectively a journal in itself.


I found that the command iopending (run with root priviliges) gives an interesting overview of the average disk queue length (= pending disk IO operations).

The rule of thumb is that it should not exceed 2. If it does, the storage subsystem cannot handle the load sufficiently.

  • While it is likely useful information, I don't see how this answers the question. How does this increase disk performance? – JoshP Sep 28 '12 at 14:40

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.