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 says it needs to restart when I try to use the Compact, Metadata or Optimize algorithms; why is that?

To use the off-line algorithms, iDefrag needs exclusive access to the volume it’s working on. iDefrag has the ability to restart into a special mode where it has exclusive access to the volume.

Whilst iDefrag is in this exclusive mode, you will not be able to do anything else with your machine and for this reason, we advise you to leave iDefrag running overnight.

The Quick (on-line) algorithm does not require exclusive access to the volume, but it’s not as thorough as the other algorithms; the Full Defrag algorithm will give the best results.

Your other options are to boot from another volume (e.g. on an external drive), or you can create a boot disk (see #3 below).

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

You can do if you want, although it’s not the easiest way of running iDefrag; allowing iDefrag to restart with exclusive access is simpler.

To create a bootable DVD, you should select “Create Boot Disk…” from the iDefrag menu and follow the instructions. You will need a DVD burner and some recordable DVD media.

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?

Yes, although it will not defragment any files that are actively being used by your database or other server software.

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?

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

Many errors actually indicate that your disk was damaged before iDefrag saw it; in this case, you should try repairing your disk using Disk Utility or a third-party disk repair tool.

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.

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.

If possible, use the bug reporting feature within iDefrag (select “Report Bugs to Coriolis Systems…” from the iDefrag menu) as this will automatically include relevant log files, providing you correctly indicate what kind of problem it is (e.g. if you indicate it's a “Crash or data loss”, crash logs will be sent).

8. 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.

9. Why is the demonstration version so crippled?

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

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 few 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.

10. 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.