Frequently Asked Questions: iDefrag

1. How safe is iDefrag?

Disk defragmentation is inherently risky in many respects. We have tried to design iDefrag such that its failure modes are as harmless as possible, and have done our best to test the product to ensure that it works as expected, but we strongly recommend that you back-up any important or irreplaceable data before using any disk utility product.

2. iDefrag won't let me use the Compact, Metadata or Optimize algorithms; what's going wrong?

The most likely reason for this problem is that you have selected the volume from which the system booted. iDefrag cannot use off-line defragmentation on your boot volume because the volume is still in use and cannot be unmounted.

To use these algorithms on your boot volume, you must boot from a different volume—typically a different partition, an external disk or a bootable CD.

3. Do you recommend running iDefrag from a bootable CD?

Yes!

While you can run iDefrag from a hard disk, customers often find that other software is using the disk they are trying to defragment; since this other software is sometimes not immediately obvious (e.g. Spotlight's indexer, or your anti-virus program), this can cause considerable confusion.

We therefore recommend that you use the CDMaker tool to create a bootable disc and run from there. You can get the CDMaker tool from the Downloads page.

4. Does iDefrag support RAIDs?

If the RAID looks like a normal hard disk to Mac OS X, then yes, it should.

5. Is it safe to use on-line defrag whilst running database or server software?

On-line defragmentation is implemented by making new, defragmented copies of existing files. If you are running software with open files that may write to those files subsequent to defragmentation, any updates made to those files once they have been defragmented will be lost.

Such software should normally be prevented from updating any files it may have open until it can be restarted. Normally, manufacturers of database or server software (which is most likely to be affected by this issue) will provide instructions for dealing with backups and restoring from backups. We recommend that you treat on-line defragmentation as a combination of a backup and a restore, and follow the appropriate instructions. For instance, it may be possible to tell database software to temporarily log updates to a separate disk or to a specific file (which could be marked such that iDefrag will not move it). Equally, you may wish to temporarily halt such services to perform on-line defragmentation.

If you would like specific advice on a particular situation, we recommend that you contact both the supplier of the software you believe may be an issue and our technical support staff, who will be happy to advise you or assist in any way necessary.

6. What should I do if it goes wrong?

Please, tell us about it using the built-in bug report feature. If there is a problem with our products, we want to know about it; if it is a serious problem, we will try to address it as soon as possible.

If iDefrag has done any damage, it should be restricted to individual files; it isn't able to (for instance) write one file over the top of another by accident (there are special checks in the code that prevent such mistakes), and will generally stop quickly if it detects that something is wrong.

7. iDefrag is displaying an error message—what should I do?

Please write down the error message. You can take a screenshot if you like, but if you choose that approach, make sure that the screenshot has been saved correctly before dismissing the error message.

When reporting problems, we would appreciate a copy of your console.log, which you can find in /Library/Logs/Console/Your Username/, and the hfs.log file from /Users/Your Home Directory/Library/Logs/Coriolis/.

Many errors actually indicate that your disk was damaged before iDefrag saw it; in this case, if repairing your disk using Disk Utility or third-party disk utility software does not solve the problem, then our technical support staff may ask you to download diagnostic tools from our site.

Please note that the diagnostic tools are unsupported; if you are asked to download them, then any assistance you need will be provided, but if you download them under any other circumstances, no technical support will be available.

8. Is iDefrag compatible with Tiger?

Yes! We are pleased to announce that iDefrag version 1.1.0 onwards is fully Tiger compatible.

9. How does the new registration process work?

We have written a separate page that has information on the new process and upgrading from versions prior to version 1.1.0. You can find it here.

10. What about G5 machines with Western Digital hard disks?

It isn't a problem with iDefrag itself, but we are currently investigating an apparent compatibility problem between some G5 machines and Western Digital hard disks. It seems that sustained read/write access can sometimes cause the machine's disk subsystem or the disk itself to stop responding. Replacing the disk with a unit from a different manufacturer seems to cure the problem, as (according to Western Digital) does using a third-party SATA controller rather than the Apple one built in to the machines.

We have had extensive contact with Apple on this issue, but both we and they have been unable to reproduce the problem, which leads us to think that this issue may affect a particular batch of units. It is unlikely at this point that further investigation of the problem will occur.

We would like to emphasise that this isn't a software problem; machines exhibiting this problem log “IOATAController device blocking bus” messages in their system logs, indicating that the ATA hardware is not functioning correctly.

Whilst we believe that iDefrag will generally fail in a way that will not cause data loss, we do not recommend using any disk-intensive product on a G5 system fitted with Western Digital disks, including iDefrag.

For more information, please see:

(Note that Western Digital only acknowledge the problem for certain of their models, and only mention the G5 tower; we have seen the same symptoms with iMac G5 systems and with other models of Western Digital disk.)

11. How about Intel Macs?

Full compatibility with Intel Macs is available in version 1.5.0.

12. iDefrag sits there saying "Allowing disk to cool"

Most likely this means that your hard disk is reporting its temperature in a non-standard manner, or that it is reporting some other data instead of the temperature, but using the SMART attribute meaning temperature.

You can disable the temperature monitoring feature from the Safety preference pane, but please send us an e-mail to tell us the model of hard disk in your machine (which you can find by running System Profiler and looking under ATA or Serial-ATA, or by running Disk Utility and selecting your disk in the list on the left hand side). We need the full model number, e.g. WDC WD2500JS-41SGB0 as opposed to WD2500JS.

13. iDefrag stops with an error message

The chances are that this is not a bug. If iDefrag is displaying an error message, then there is something wrong with your filesystem, your disk, or even with your machine itself.

If the error message is telling you that iDefrag could not move part of a file from one location to another, and you see in the list of error codes the text “errno 5”, then it most likely means you have a bad block. Please read our page about bad blocks to understand what this means and what you can do about it.

Note that “errno 5” is quite a general error code; if the disk itself seems to be “stuck”, cannot be accessed by any software without power cycling the unit, seems to be a lot slower than normal, is making funny noises, or is exhibiting other unusual symptoms, then it may be that there is a more serious fault with the disk hardware. This could range from a fault with the logic board of your machine through bad controller chips, faulty firmware, a faulty logic board on the disk, or even some sort of mechanical failure. If you do have other symptoms like these, please contact us and we’ll endeavour to diagnose the issue in more detail for you. N.B. if your disk is making funny noises or emitting smoke, switch it off.

If the error does not contain the text “errno 5”, please do let us know about it, as we may be able to offer further advice on what you can do to resolve the problem.

14. Why is the demonstration limit so small?

We have put some considerable thought in to what to do with a demonstration version for iDefrag.

The demonstration version of iDefrag will not defragment disks that are bigger than 100 MB (yes, that's 100 MB, not 100 GB). Many are quick to point out that disks that small don't exist any more. You can create a disk image that small using Disk Utility although then you'll need to go to the effort of creating fragmented files on that disk. The reality is that you can't effectively test iDefrag using the demonstration version.

What we are trying to do with the demonstration version is give you an idea of what it can do and that it's a well thought out and designed program. You can see all the features iDefrag has and you can use it to see if you need to defragment your volumes.

Unfortunately, whilst the majority are honest users, there are a lot of dishonest people about. We have suffered significantly from piracy and have chosen to take an aggressive stance towards it. We could choose to ignore it as others do or factor it into our pricing but we feel this is unlikely to be effective as our products aren't used frequently and price is important. This is why we've ruled out making a time limited version of iDefrag.

Whilst it's true that defragmenting is a routine process, it's something you only need to perform every couple of months. If users could download a demonstration version and test it and find it works for them, they're not going to buy it because their disk doesn't need defragmenting any more and they can just download another demonstration version in a few months.

There are plenty of independent reviews on the Internet (e.g. VersionTracker or MacUpdate) that you can read to help you to decide whether to purchase iDefrag.

Of course, we welcome any suggestions as to how we could improve the demonstration version but bear in mind that we've spent some time thinking about this ourselves.

15. How do I access older versions of iDefrag?

Customers wishing to download a previous version of iDefrag should use the iDefrag Atom Feed, which provides download links and release notes for all prior versions of iDefrag.