I work on media files as per my profession. I find my Mac (Mac Lion) going slower day by day. I think it will be beneficial to defrag the drive but didn't find any Apple tool for it. I want a an effective third party Mac defragmenter for my Mac drive.
You might be better off checking there is enough free space for new files.
There are some utilities to do defragmentation like iDefrag
DriveGenius does what you ask.
There aren't many apps that do this on mac since actual filesystem fragmentation both rare and rarely a cause of measurable slowdown. Mac OS X automatically defragments files that are likely to cause a slowdown in addition to automatically optimizing hot (often used) files to a fast and not-fragmented part of the drive.
The HFS+ filesystem directory / catalog itself can become fragmented over a long time but you can fix that easily. Back up to time machine and an erase install / migration back cures that issue without needing to spend money on a live tool. DiskWarrior also helps to rebuild HFS+ catalogs in addition to the already mentioned Drive Genius.
Best of luck - keep looking if you find defrag isn't what the doctor ordered on your mac.
I agree with Mark. Usually, I don't fill up a drive past 80-85%, as the slower parts of a mechanical drive begins around that point. HDs have different speeds and access time depending on the location on the disk.
Therefore using an app like iDefrag could help (remember to backup your files before!) but will likely need to be done on a regular basis to provide a continued result, and I'm wondering if the time you're gonna spend on this isn't gonna be for nothing.
I would suggest using RAID-0 or better yet RAID-5 drives setups. Bit more expansive, but speed will be much more constant over a longer period of time, but this setup also carries more risk (especially RAID-0), therefore you NEED a backup, could get expensive...
An SSD is a good solution, the only problem is the capacities. A good, fast and reliable 204 Gb SSD retails for ~500$, a 480 Gb for ~900$.
If we go little deeper we see that the HFS+ file system allocates memory not on the basis of first free space first but on the basis of largest free space first.
This technique, although reduces the chances of fragmentation but doesn't stops it totally.
Its right that fragmentation hardly matters when you are a simple home users but for professionals (Like me) a slow Mac matters a lot.
So, now I have two programs for defragmentation. One from Stellar drive defrag and another is idefrag from coriolis.
Let me try them and see if I can get some speed in my Mac.