Basic Usage


iDefrag’s user interface has been designed to be as simple and straightforward to use as possible, without compromising functionality. The screenshot below shows the main elements of the iDefrag user interface, namely the main window, containing a display of the disk, the key panel, which shows what each color used in the main display means, and the information panel, currently displaying information about the Mach kernel (the blue area in the centre of the display).

Note also that unlike other disk defragmentation tools, iDefrag displays both a zoomed-in block-by-block view of the disk and a display showing the distribution of files on the volume, which can also be used to quickly jump to another area of the disk. (Due to the amount of data that must be scanned to update the whole disk display, updates are performed lazily, in the background… the frequency of updates during defragmentation can be set from the Preferences panel.)

Whilst there is nothing displayed there in the picture above, during defragmentation, progress information is displayed at the bottom, to the right of the tabs.

Basic iDefrag usage goes something like this:

  1. Select the required defragmentation algorithm.

  2. (Optional) Select an appropriate class set; this controls the coloring visible on the display, as well as the behavior of the defragmentation algorithms.

    N.B. You may need to use a custom class set if your disk contains immovable “auth files” as used by some older software for copy protection, otherwise iDefrag may move the files, which could prevent the software from working.

  3. Select the volume you wish to defragment from the list of Volumes.

  4. (If required) Click the lock to authenticate.

  5. Press “Go” (or choose it from the Defragment menu).

    WARNING: As with all disk utility products, we recommend that you ensure that you have current back-ups of any irreplaceable data before defragmentation commences. This applies to both on-line and off-line defragmentation, both of which could cause data loss if things go awry.

    We also strongly recommend that you do not run any disk defragmentation software on a disk unless you know that it is in a valid state; at the very least, you should check your disk using Disk Utility or other third-party disk software before using this product.

  6. Wait for iDefrag to finish working, or press “Stop” at any time to abort.

During defragmentation, the iDefrag display can be set to follow the progress of the defragmentation algorithm, or it can remain under user control. Other than that, the user interface will continue to work just the same way during defragmentation that it does when simply examining a disk—you can hover over a block to temporarily display information about the file occupying that block, or click on a block to select that file (highlighting all its extents with a thin line in the system highlight color). You can also stop the defragmentation from the toolbar (or the Defragment menu) at any point.

Unlike other defragmentation products, iDefrag works in the background, so you can get on with other work whilst it is running. We do recommend, however, that if possible you limit your use of the machine whilst iDefrag is operating; defragmentation can require a large amount of memory—although we have done our best to keep memory requirements modest—and a system crash during defragmentation could result in disk corruption. Generally speaking, disk damage in the event of a crash or other failure will be restricted to the file(s) on which iDefrag was working.

It is possible to pause defragmentation in which case iDefrag will stop what it is doing so that it does not consume any processing power. However, with the off-line algorithms, you will not be able to access the volume (iDefrag has to prevent modification of the volume so that it can resume).

If you stop defragmentation mid-way through, your disk will be left in a useable state, albeit one where iDefrag had only half completed its job. If you were to run the process again immediately, iDefrag would continue from where it had left off. Obviously, the longer you leave it, the more likely it is that iDefrag might need to start again from the beginning.