|Reader Reports on iDefrag for OS X
Last software update: v1.6 (Jan. 2007)
Reports Last Updated: 8/30/2006
This page has reader reports on using iDefrag for OS X. (Also see their FAQ.)
As of early Jan. 2007, the latest version is 1.6 which notes these changes/fixes:
- Thermal monitoring: iDefrag now monitors the temperature of your
disk, and will pause to allow the drive to cool if it exceeds a certain
- iDefrag now uses IOKit rather than Carbon for power management,
which allows the display to sleep during defragmentation.
- iDefrag now remembers the last unit set by the user in the file
size field in the inspector.
- The SafeSleep image has been reclassified as a type of swapfile.
- The most fragmented files list is now sortable (by clicking the
- Sounds and e-mails are now sent after defragmentation completes,
but before re-mounting the disk. This will avoid problems on machines where
the OS insists on asking for authorisation before mounting.
- Fixed a problem with the pause/resume function.
- Fixed the "Check for Errors" feature so that the "Repair" option
works from a bootable CD.
- Fixed a performance bug on very full disks containing large
files. iDefrag will still slow down on such disks, but not as much as
- Fixed a bug that was causing fragmentation statistics for the
special files to be mis-reported.
Requirements: Mac OS X 10.3.9 or later.
Reader Reports (most recent first)
I welcome other iDefrag user comments (include your iDefrag version and OS version used). Thanks.
(Note: reports below were not using the latest version (v1.6 as of Jan 2007)
"Just saw your iDefrag report page. Here are my 2 cents.
I bought iDefrag in February 2005 and have never had problems with
it. I used it on my previous dual G5 and now on a Quad G5.
I think iDefrag is well done, it offers several different kinds of
defrag, and respects more recent OS developments like the "hot zone"
etc (IIRC that came with 10.3, so its not all that recent... but
certain other defrag apps don't respect it).
Prior to using iDefrag I usually boot from another disk with an
"emergency" copy of OS X (it also contains Disk Warrior, Anti-virus
A full defrag takes rather long with today's large drives, so
recently I often find myself doing an on-line defrag, which only
defrags fragmented files, but not fragmented free space.
Note an on-line defrag can be done without unmounting the drive, so
restarting off another disk/disc is not strictly necessary (but still
a good idea). Of course an on-line defrag is much quicker than a full
defrag. iDefrag shows some statistics upon selecting a volume and
thus allows a user to decide whether or not a full defrag would make
As for copy protection:
Yeah, so I have to log in to download an update, big deal. The change
from requiring a serial number to a personal "key" file was nothing
new either, other apps do the same or worse (like online-activation).
I don't see a problem with that and understand that small companies
need to protect their income. The key file can be used with updated
versions, so instead of saving a number one has to save a file.
Contact with Coriolis:
In my experience, they are quick, friendly and open to suggestions.
Note it is the developers themselves who answer support emails (big
plus in my book). Some stuff I suggested was later built into iDefrag
(for example no white gaps when using small squares, or custom sized
squares to begin with), much to my joy. :D (Then again I wasn't the
only customer requesting these features either)
On a related note:
Earlier this year I bought iPartition to resize a 1956 GiB (2100 GB)
array to 2086 GiB (2240 GB). The added space came from replacing
eight 300 GB drives with 320 GB ones in a RAID 5 setup. The resize
failed, as the resulting volume was ~0.04 TiB instead of ~2.04 TiB.
I assumed it was due to a shortcoming in iPartition related to the
volume being over 2 TiB, because 2 TiB is 2^32 blocks (512 byte
blocks), so this is kind of a major threshold for filesystems/storage
(much like 2^32 (or 2^31) bytes is for memory).
Anyway, I reported this, said I'll not use iPartition again and asked
for a refund. They replied that they fixed the issue (which was due
to an Apple Partition Map limitation apparently) and refunded the
money - against their usual refund policy BTW, but well justified in
this case IMHO. ;)
And in case you were wondering, I didn't lose any data, but tediously
had to restore a distributed backup - exactly what I wanted to avoid
by using iPartition. :P
In conclusion, I like iDefrag and have no problem with Coriolis at all.
"I've just purchased iDefrag ver. 1.2.2. (Apple Dual 1GHz PowerPC G4,
2G Ram, OS 10.4.7).
My comments are as follows (and let me preface my comments by saying
that before I install and work with any new application, I always
read every bit of the instructions FIRST):
1. RELIABILITY: I have never before had a HD optimization program
that works nearly as well as iDefrag. I'm not going to mention
competitors' names here, but it seemed my computer was running
slower... and slower... a n d... s l o w e r. When I upgraded to
my present OS (jumped from OS 9xx to OS 10xx), I performed a clean
install, reinstalled all my updated apps, drivers, existing files,
etc., including iDefrag, read all of iDefrag's instructions, chose my
preferences and optimized. Now, when I fire-up my computer, the
white screen comes on, and then the desktop immediately sparks to
life. IMMEDIATELY! (No more waiting for that lazy start-up bar to
hobble to its end.) My old G4 is actually running as fast, if not
faster than the first time I took it out of the box! I also
optimized my laptop with iDefrag, and experienced the same
outstanding results (and I hadn't performed a clean install on the
2: REGISTRATION: Quick and easy. Not a glint of a problem.
3. TECH SUPPORT: I had a few questions (i.e wanting to be sure I
chose the correct preferences, etc.). The response from iDefrag was
in my e-mail the next morning. Their reply was professional,
detailed, and quite friendly.
Note: I am using an external firewire with a basic OS and iDefrag
(along with my trusted Disk Warrior) for optimizing, rather than
using a start-up CD for optimizing (as strongly suggested by
Coriolis's, iDefrag--found in their instructions).
SUMMATION: For me, this is one of the few companies that makes a
product that really does it's job--fast, efficiently and properly--
all backed up by great tech support which is prompt, courteous and
knows what they're talking about. Installation and registration was
a breeze, and I've never before experienced any optimization software
that comes even close to doing its job like iDefrag.
For me? I give Coriolis iDefrag the highest regard and recommendation!
"I know you keep a page on iDefrag so I'd like to give you some honest
feedback. As far as the product goes, I have only used it on my 500Mhz Ti
PowerBook and it seems to function as advertised. I haven't had any
However, the issue I have is the negative language of the website -
threatening anti-piracy notices, IP logging and you have to login
every time you want to download an update - and are reminded that
your personal info is included in every single copy of the software
you register. iDefrag even puts a warning in with the prefs file in ~/
Library/Application Support! All that and activation to boot!
Again, I am a legitimate user. I don't want to be threatened and
warned every time I use an application. It's ridiculous. I contacted
Coriolis and expressed my dismay at their negtaive language. I
suggested saying, "Thank you for supporting our company and helping
to make our products better for everyone. Your legitimate purchase
supports our families and helps fund continued development."
Coriolis responded. This verbatim clip from Alastair Houghton's e-
mail says it all about their company:
(rather than a single quote I asked Sean to send a complete
copy of their reply-Mike)
"From: Coriolis Systems Limited (Support Dept.)
Date: October 18, 2005 7:38:36 AM EDT
To: Sean R.
Subject: Re: [Ticket#2005101810000429] Complaint
We don't see why you should expect us to be polite. We certainly
don't mind suggestions as to how to improve our site, however.
As far as IP logging, almost all web servers actually log IP
addresses, as I'm sure you are aware; we're just making it obvious. And I should
also say that whilst it's certainly true that the hardened software thief is not
going to be put off for a moment, it does make casual pirates think twice.
If you would like to point out a specific piece of text that you find
objectionable, we will certainly consider editing it.
Coriolis Systems Limited is a limited company incorporated in
England and Wales"
The only thing I know for sure is that their customer support has
made me regret doing business with them. If I had known that this was
the way they ran their shareware company, I would not have purchased
their product. I am putting iDefrag in the Trash and moving on.
(Note - reports below were from before v1.06 was released)
Bob wrote that he's still having problems with iDefrag on his upgraded Pismo (1.05 update didn't help).
"No help. Coriolis has offered to help in any way they can, but after
spending yet another day on this puzzle I've concluded that the only
way to find out for sure would be to swap in another hard drive and try
iDefragging in that one. It could very well be true that there's a
minor glitch iDefrag is picking up which my repair utilities don't
notice. Considering the fact that the Pismo is now my #3 machine and
doesn't even get used that often, I can't justify spending any more
time on this for now.
Rgds, Bob F."
His previous follow-up:
"(using iDefrag 1.04) Still a no-go on my 900mHz Pismo. I updated both partitions from 10.3.4 to 10.3.7 and at least now I get error messages which I can forward to developer Coriolis.
It still seems that iDefrag is either detecting
catalog errors which Disk Warrior, Norton DD, and TT Pro cannot, or
these are false positives. Basically, iDefrag puts up an error message
about half-way through the defrag process and won't proceed. Says it
can't find certain resources. More later.
Cheers, Bob F
Bob sent a note about 1.05 (see above info) and hopes it will solve
Although not a iDefrag report, this mentions using CCC to
backup/restore a drive as his method of defrag.
"Hi Mike, I haven't tried iDefrag. For defragmenting partitions I suggest using CarbonCopyCloner and a second hard drive. Just copy your fragmented partition to the second drive/partition and back again.
Practically no risk of data loss. On the contrary, you have a backup afterwards.
Just a donation to Mike Bombich!
Works also for sparse disk images, e.g. FileVault
cons: You need disk space.
I tried this out on my FileVault protected home sparse image. First it was ~800MB, it dropped down to just 350. I guess though that sparse disk images are more affected by fragmentation than hard drive partitions. Also, I had some permissions issues afterwards... But I would guess that the method works fine for hard drive partitions.
I've been leery of filevault personally since some problems with it
were reported early on (when 10.3 was first released) plus some
reports on performance impact (at least on some systems). I've used
Carbon Copy Cloner for years (very useful) but don't usually wipe
and restore with it as a way to defrag the disk. (if you missed it
last year I posted Interview/Q&A with Mike Bombich, author of Carbon Copy Cloner.)
1.04 worked fine for me on my Dual G5, I did the "quick", then the "meta.", then the "optomize". This took a total of about 3 hours...
Another follow-up from Bob (he also sent a note on the iDefrag v1.04 update linked above)
My iPartition test finally finished by the time I woke up this morning.
80 gig drive, subtracting 5GB from one 10.3.7 partition and adding it
to another on my Titanium PB. It works slowly, only one partition at a
time, and I had to let it run all night after setting it to do the
second step. Worked perfectly though. I had used iDefrag 1.0.3 on each
The only oddity I have noticed so far is that NUM 8 on each partition
had to be updated again with two Live-Update files, 3.8MB and 6.1 MB
respectively. Disk Doctor is still the best, but I'm delighted to
finally replace Speed Disk which never worked right with X anyway.
Regards, Bob F."
Works fine in my 15" AlBook running 10.3.7. However, in a
900MHz-upgraded Pismo running 10.3.4 it doesn't seem to work at all.
I've emailed Coriolis and will get back to you on this.
It's always SOMETHING...
Here's a link to the story of one not-very-happy iDefrag customer published on the french website Macbidouille.
Apparently there's a confirmed bug in iDefrag affecting files larger
than 4GB (as in video editing for example) and causing loss of data.
The bug is fixed in version 1.03.
(added 1/3/2005 from late friday email)
I have used iDefrag from the beginning - I was one of the first
purchasers - an do not work for them in any way. There were severe
problems with versions 1.0, 1.01 and 1.02. I helped do an extensive
amount testing (to protect my investment) including trashing my disk
more than once (72+ GB of data). I'm running MacOS 10.3.7 on a dual 2
GHz G5, 2 GB of ram and a 160 GB HD. I backup using two external 160 GB
USB2 disks; one disk is backed up with Retrospect and the other with
I found the developers to be extremely knowledgeable about disk
fragmentation and they understand HFS+ inside and out. There were also
responsive to my (and others) discoveries and worked day and night to
remove their problems. I requested some of their fragmentation
creation programs, inspected them (and even made some recommendations
that they liked) and ran them myself. With version 1.03 I have been
unable to find any further problems and I'm able to defragment my disk
The problems in version 1 and 1.01 were fixed basically by the next
day. The problems with version 1.02 were quite vexing and it took quite
some effort to find and fix them. The serious bug fixed in version 1.03
due to an arithmetic error when dealing with a file that has a one or
more fragments that are 4GB or larger in size. Sure enough when I
helped with the testing I tested many things but not that and boy did
it screw up!
Despite what some may say MacOS X 10.3.x disks do get fragmented and,
in fact, they can be fragmented quite severely and this affects
performance in some circumstances. The HFS+ file system does an
excellent job of preventing fragmentation for files less than
approximately 20 MB in size. When HFS+ does have to fragment a file it
does a lovely job of placing the fragments in optimal locations to
minimize the fragmentation penalty.
Files that become fragmented are the large ones: VirtualPC disk images,
large sound files, video capture files (iMovie, FinalCut and FinalCut
Express), some database files and large download files. Even some of
the MacOS X update files can become fragmented. Over time, especially
when there are multiple streams of data being saved to the disk
simultaneously, a fair amount of fragmentation results. Some of my
video capture files (and my VPC disk image) had over 10,000 fragments,
ten files had between 100 and 1000 fragments and many tens of files had
between 10 and 100 fragments.
If one downloads large files while also working on large files it is
all too easy to land up with fragmentation.
Most people can live with fragmentation that the file system creates -
it's quite small. But in certain situations the fragmentation can be
significant despite what the file system can do and defragmenting is
Yes one can defragment their disk by using SuperDuper! (or something
similar), rebooting on the backup disk, formatting the original disk
and then using SuperDuper! in the other direction. This is quite time
consuming and the time necessary grows as your data grows. I use a
"smart backup" which only saves what has changed since the last backup
and then an iDefrag run when I want to clean up my disk - a savings of
Those without the ability to perform a full backup may backup their
critical data (/User?) and still benefit once iDefrag is dependable -
and it's getting there rapidly from what I can see.
What do I get out of this? Some of my video processing is now 3-4%
faster. On processes that take hours this counts.
I find the iDefrag documentation to be quite good - clear and well
structured. The ability to defragment using different models and by
file type is a very nice feature.
I used iDefrag in its first release version (as supplied by Coriolis
to iPartition licensees) on a backed-up 20 GB partition used
exclusively for data without any problems whatever. The visual
display is excellent, letting you know how things are progressing.
While I don't recommend writing to that partition while things are in
progress, there is no problem letting it run in the background, and
there was no problem with any of the files (checked at random) after
the fact. I'm not firmly convinced that defragmentation needs doing
very often, but certainly iDefrag worked as advertised.
The reader that requested the feedback sent a note regarding the system requirements:
Mike, I saw the specs and sent this (to the developer) a few minutes ago and also enclose the reply, which was very prompt. The 1.03 release is apparently new today.
(copy of his mail to them/their reply follows)
Current Release: 1.03
System Requirements: Mac OS X 10.3 or later, 500MHz PowerPC or better, 512MB RAM.
So, a G3 400 ghz Pismo with 764 mb RAM running 10.3.7 is not going to run your product, is this correct?
It should work OK. We were just a little reluctant to specify less
than 500MHz because the slowest thing we have tested (ourselves, as opposed to our beta testers) is a 667MHz PowerBook G4.
Hi Mike. I bought a copy of iDefrag 1.0 shortly after I found out
about it. I immediately tried to use it to clean up several drives on
my G4 DA (1.33 GHz / 1.5 GB RAM / 1.33 GHz OWC card).
iDefrag has four different algorithms: Compact, which collapses all
data on the partition into a contiguous area; Metadata, which makes the HFS+ file system data structures into contiguous files; Optimize, which makes most data contiguous, organizes boot volumes by file type (library, application, etc.), and respects the HFS+ Journaled "hot
zone"; and Quick (On-Line), which simply makes contiguous copies of most fragmented user files. Each of these algorithms has complementary strengths, and I discovered that it is most effective to use more than one of them when cleaning up a drive.
I found that iDefrag performed optimally on my Mac OS X boot partitions when the algorithms were applied in the following order: Quick, Metadata, Optimize. If only Optimize was performed, some data and HFS+ administrative files were incompletely defragged. I would not recommend using the Compact algorithm on a Mac OS X boot partition, particularly if it is set up as HFS+ Journaled. That is what the Optimize algorithm is for. The Compact algorithm works fine for data drives.
With version 1.0, I successfully defragged some of my data and Mac OS Classic boot partitions. However, the Optimize algorithm failed to
complete on my usual boot partition (while booted from a FireWire drive with 10.3.7 installed), giving an error message that said "this should never happen". I immediately checked the drive with Disk Utility and found no problems. I was not so lucky with my audio library partition, which contained a number of heavily fragmented large files. iDefrag reported a couple of HFS+ errors, and Disk Utility subsequently reported that parts of one file had been overlaid onto itself! After Disk Utility finished its work, I discovered that the file had indeed been damaged. Fortunately this file was easy to replace. But it again drove home the rule: Always back up your crucial data before
To their credit, Coriolis Systems responded promptly to my bug reports, and had released one update in the week before Christmas, notified customers on Christmas Eve of a pending update and the conditions under which the current release would misbehave, and two additional updates in the following week (the last coming this morning). As I write, the current release of iDefrag is 1.03. The most recent release fixes a bug I have not yet encountered, with files larger than 4 GB which also have at least one contiguous extent of 4 GB or more. This would most likely apply to people working on (e.g.) large audio or video projects.
I have found the iDefrag user interface relatively easy to use and very
informative, similar in some respects to the (Classic) Norton Speed
Disk UI. There are some quirks, but those are to be expected of such a new application. I suspect the Compact and Optimize defragmentation algorithms could be further tuned to reduce the amount of work done to relocate files that are already contiguous and in the desired destination zones, but as a programmer myself, I realize that is a difficult problem (known generically as the "bin-packing" problem in computer science).
I feel iDefrag is a good value for the money, and Coriolis Systems has shown it is extremely responsive when bugs are reported to them. I would not hesitate to recommend it. I would, however, caution that one should always back up any critical data before defragmenting with ANY tool.
Happy New Year, Mike!
I successfully defragged one 10.3.7 partition using 1.0.1 but after
reading today's warning from the developer, I with I'll wait a few
weeks before trying it on another! (they've released a 1.0.3 version now-Mike)
Sure glad I didn't try it on my VPC partition.
I bought iPartition about two weeks ago and used both iDefrag Lite (that comes free with the Ipartition purchase) as well as iPartition with good results using iPartition version 1.07 and iDefrag 1.02 running OS 10.3.7. By good results, I mean that I took my 60 external gig OWC firewire HD reducing the partitions from 4 to 3 and resized all three partitions. And I used iDefrag to compact the data first to make the repartioning easier and safer. There was no loss of data and all three partitions still boot my PB as before the repartioning process.
I was so pleased with the IDefrag product that I also used the compact/default mode of iDefrag to defragment my two SCSI internal hard drives in my G4 Mirrored 867 dual and the 60 gig HD in my 17" PB. I actually felt an increase in speed on two of the partitions on my internal hard drives (not the PB). On a lark, I even defragmented my eDrive on two of my internal hard drives with no ill effects. They still boot the computers.
But, of course, the risk is non-existent for me since I always have a backup in case of problems. Some users claim they lost data using TTP4, Norton Utilities, iDefrag and even Disk Warrior. I have used all of these utilities with good results and continue to do so (not NUM anymore since they stopped updating the product) without fear because I always have a backup. But I guess some users never learn despite the developers' repeated warnings about creating a backup before using their disk utilities.
Though successful in the repartioning process, I did find it rather difficult to repartition the external firewire HD. Listed below is a copy of some of the sections I wrote to tech support with their responses.
Due to space, I didn't include the copies of Ted's mails on that here.
I welcome other iDefrag user comments (include your iDefrag version and OS version used). Thanks.