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[www].se [ftp].se [mirror].us [mirror].de
iDefrag_1.7.3_OS_X_10.3.sit (4.88 MB)
MD5: 143958f7ac275b0993d3f5e8595f8be1
For Mac OS X
[www].se [ftp].se [mirror].us [mirror].de
iDefrag_2.0.5_OS_X_10.4-10.5.sit (14.87 MB)
MD5: 7cb9364f6e4bab666280834d520c68d2
For Mac OS X
[www].se [ftp].se [mirror].us [mirror].de
iDefrag_2.2.8_OS_X_10.6-10.9.sit (18.64 MB)
MD5: 68ea2201e90a723649a1beae3cde066f
For Mac OS X
[www].se [ftp].se [mirror].us [mirror].de
iDefrag_5.1.3_OS_X_10.10-10.11.sit (14.19 MB)
MD5: 81bfabd600aa9f3b5a2a0e7824b654de
For Mac OS X
[www].se [ftp].se [mirror].us [mirror].de
iDefrag_5.3.1_OS_X_10.12-10.13.sit (13.79 MB)
MD5: 199301794a227b51d6643f28e862bf47
For Mac OS X
Guides on emulating older applications

Defragment and optimize your disk for improved performance.

This software and its licenses have been made available for free by its developer, Alastair Houghton.

Features from iDefrag in 2006:
-Send email notifications or make noises when done.
-Supports HFS and HFS+ (Mac OS Extended).
-Supports case sensitive and journaled filesystems.
-Supports adaptive hot file clustering (“Hot Zone”).
-Four powerful defragmentation algorithms:
-Compact data, moving all free space to one place.
-Optimize filesystem metadata.
-On-line defragmentation.
Defragment whilst your disk is mounted.
-Advanced programmable optimization.
Rearrange your disk the way you want.
-B-Tree metadata file compaction/optimization support.
-High performance user-defined file classification engine
-Per-block and accurate whole disk display.
- Detailed statistics so you know whether you need to optimize.
- Inspector allows you to view details of individual extents/files.
- Quickly jump to specific files to examine them in more detail.
- Altivec accelerated display for improved performance.
- Auto-update feature ensures you always have the latest version.
- AppleScript support.

NOTE: Do NOT use iDefrag on an APFS volume and/or an SSD.


iDefrag_1.7.3_OS_X_10.3.sit contains the application (.dmg) and license file.
iDefrag_2.0.5_OS_X_10.4-10.5.sit contains the application (.dmg) and license file.
iDefrag_2.2.8_OS_X_10.6-10.9.sit contains the application (.zip) and license file.
iDefrag_5.1.3_OS_X_10.10-10.11.sit contains the application (.dmg) and license file.
iDefrag_5.3.1_OS_X_10.12-10.13.sit contains the application (.dmg) and license file.


iDefrag and other useful tools created by Alastair Houghton are also available from the Coriolis website.
If you find this software useful, Alastair would be grateful for any donation made towards it (via PayPal link on Coriolis web page).


Architecture: PPC x86 (Intel:Mac)


OpenSourceMac's picture
by OpenSourceMac - 2020, September 17 - 4:26pm

OK so more info on using this in a real-world situation. I have a 10TB Mirrored-Raid that I keep my media collection on, and have wanted to share it with my main TV via Connect360 ( ) and while it worked, it would cut-out pretty often because of seek-times on the drive from fragmentation. Finally did more deep-dive into iDefrag and found out that a lot of the problems I had previously were due to a habit Western Digital drives have to stop-responding when hot, that the company actually knew about and warned owners about. My media drive is HGST (Hitachi), and sure enough after defraging nearly 5 TB over a week, I didn't have ANY PROBLEMS - and now the data seeks so fast that spooling via Connect360 works flawlessly - via an Ethernet-network that both the Mac, 360 share and get internet off of.

A few tips...

1. As always, if you have a way to back-up the data, do it first.

2. If defragging a system drive, using "Full" defrag is a good idea very occasionally to get system-files and extensions optimized. You don't have to burn a disc, as the program is able to reboot in place - simulating a disc boot to perform the action.

3. For normal defragging of either a system drive or storage drive, the "Full" option usually isn't needed. Instead, the quick "Online" mode works very similar to the way Windows does it and defrags files right were they are. It is really fast and can even be done to the system drive you are booted into. There is an option to check each file as it is copied to verify it copied correctly, and this is a great idea. It doesn't take too much longer and you know for sure the file is copied correctly before the old location is overwritten.

4. THE "Metadata" option is next. For a system drive this must be done from the virtual reboot, but on a storage it can be done while logged-in. This fixes and if the option is selected, rebuilds the B-Tree, Extents and Volume Bitmap, and can defrag/compact it. THIS IS WERE SPEED IS REALLY GAINED. Normally, fragments of this are scattered everywhere, and can make a big drive take forever to populate. My Big drive when from taking nearly 12 seconds to 2 seconds of seek-time to populate icons!

5. The Last option (optional) isn't really necessary for a system drive, but helps prevent future fragmentation on storage drives and that is the "Compact" option. It will scooch everything together to prevent small gaps fragmenting new writes later. It doesn't take as long a time as you might expect as long as you don't select the "Compact as much as possible" option, which will movie a 2GB file just because there is a single unused block ahead of it.
As stated, compacting isn't really necessary, and doesn't even improve speed, but is nice if you plan to defrag very often, and also, can help to clone to a smaller drive if needed later (with iPartition).

Why not use "Full" for everything? The Full defrag option will relocate every file on the drive, placing system files near the hot-zone (Highest speed sectors). For a System drive, this really only needs to be done once after a new install or after a drive is re-imaged, because Disc Utility will often copy the drive in order with Applications put in front - and can make the system less responsive. For Storage drives, the only files that benefit from optimization are B-Tree and Catalog files and the Metadata defrag does that anyway, without effecting other files wherever they are.

OpenSourceMac's picture
by OpenSourceMac - 2020, January 15 - 9:34pm

***Update to This***
I used CCC to copy the data from the corrupted drives and it was only two files that were damaged (maybe were already) and the system did run faster - so as is the never-ending truth, have backups before using this.


Just a warning to everyone on this app. I've had considerable data-corruption on two different drives I've used it on. Ironically, the drives/systems don't seem to know it and seem to work fine, but neither one can be back-up now.