DiskWarrior 3, by Alsoft
Posted: 16-Dec-2003

4 out of 5 Mice

Vendor: Alsoft Type: COMMERCIAL

Reviewer: Todd Ferguson Class: UTILITY

Alsoft DiskWarrior is a disk repair utility that resolves directory damage to files and folders by building a replacement directory from data recovered from the original directory. The replacement directory is optimized, thus speeding up overall disk performance. Disk Warrior will work on any Mac OS Standard (HFS) or Mac OS Extended (HFS Plus) disk even if the Finder cannot mount it and display it on the desktop.

DiskWarrior fixes wrapper volumes, master directory blocks and alternate master directory blocks (HFS), volume headers and alternate volume headers (HFS Plus), volume bit maps, catalog trees, and extent trees.

DiskWarior cannot rebuild the current startup disk or any disk from which it is running. DiskWarrior can repair any Mac SCSI, USB, FireWire, IDE, or RAID disk meeting the above requirements. DiskWarrior rebuilds directories on disks as large as 2,000 gigabytes (2 terabytes).


  • Mac OS X 10.2 or later
  • 128 MB Physical RAM (256 MB recommended)
  • 6MB disk space

Reviewed on

Pismo G3 powerbook, Mac OS X 10.2.8 (Jaguar), 768MB RAM, 400MHz

Note: DiskWarrior 2.1 is included on the DiskWarrior 3.0 CD for Mac OS 9 and earlier systems. This review only addresses DiskWarrior 3 for Mac OS X.

In Use
The software comes on a bootable OS X 10.2 Jaguar CD, so it will boot all the latest computers except the new G5's and PowerBooks manufactured since September 2003. The CD also contains DiskWarrior 2.1.1, which was the last Classic version.

To run the application, just insert the CD into your CD-ROM drive and restart your Mac while holding down the 'C' key to boot off the CD. DiskWarrior opens with the main window displaying the mounted drives in a pop-down list box. Select the drive you want DiskWarrior to rebuild and click the 'Graph' button.

While DiskWarrior is known mainly for fixing disk problems, it can (and should) be used for preventative maintenance. Run DiskWarrior on one of your volumes, and it creates a graph that indicates the degree your directory is internally fragmented (the term directory is used to represent the entire file catalog on a volume). Each part (node) of the directory is assigned a color along a gradient between white and dark blue depending upon its optimized position. The graph of a perfectly optimized directory is a perfect gradient from white to blue. Fragmentation interrupts the gradient. The more distant a fragment is from its optimized position the greater the difference between the color of the fragment and the color of the same position in an optimized graph.

I try to run DiskWarrior once a month. When I first ran it, 7% of my directories were corrupted. I clicked the "Rebuild" button, and then took a break while DiskWarrior crawled through my hard drive's directories building a preview report of all the errors and what it wants to do to correct them. This process takes time, and it's an interactive process. It doesn't actually perform the "rebuild" until step number 10. The amazing thing about the disk preview report is that it's kept in memory until the actual rebuild takes place. This provides two benefits. First, because no disk I/O is performed, if you have a power failure or your computer crashes, your disk is unchanged.

The other benefit of keeping the report in memory is that it gives you the opportunity to preview and cancel the operation without changing the disk. You can preview the disk report, and if not all of your files are recoverable (e.g., physical damage to disk or partially overwritten files), you can copy specific files from the preview disk to another disk, and then cancel the rebuild. By choosing to cancel, your disk is left unchanged. Other disk utilities, such as Norton Disk Doctor, perform disk I/O during repair operations, so once the process begins, you are vulnerable to power outages, and you are not offered the opportunity to cancel and leave your disk unchanged.

At first I thought the only time your disk would be vulnerable to a power outage is during the actual step where the new directory is being written to your disk. However, DiskWarrior resolves that concern by using a fail-safe method of installing the new directory. When DiskWarrior writes the new directory to your disk, it first writes the rebuilt directory to free space (which requires that you have at least enough free disk space to hold this temporary directory). Once this new temporary directory is in place, DiskWarrior instructs the system to use the new directory, and performs tests on it. After the tests, the new rebuilt directory is then copied over the original directory and the system is instructed to use it (the temporary directory is set back to free space). If the OS is interrupted while writing to the temporary directory, your system boots up under the old directory and you can then run the rebuild again. If the OS is interrupted while copying the temporary directory over the permanent directory, the system boots up using the new directory. Your directory is never at risk.

DiskWarrior also comes with a monitoring feature. You have the option to install DiskWarrior on your hard drive, enabling DiskWarrior's hardware monitoring capability. This feature uses a drive's built-in SMART technology (Self-Monitoring, Analysis, and Reporting Technology). Currently OS X does not report errors from SMART hard drives, but DiskWarrior provides the ability to monitor a SMART hard drive and report a pending drive failure. This is a critical feature because it could provide an indication of a failing drive, giving you the opportunity to backup data before the drive fails completely. This feature does not currently work on SMART SCSI drives.

If you own another disk repair utility (e.g., Symantec Norton SystemsWorks), run DiskWarrior first! Other utilities patch the directory, so you run the risk of loosing directory data, making it impossible for DiskWarrior to completely recovery the directory data.

The DiskWarrior 3 CD contains a Quick Start Manual and a PDF version of the full DiskWarrior Manual. More info can be found at the
DiskWarrior home page.

DiskWarrior 3 is a remarkable disk repair utility that is very easy to use. I like the graphical interface, which depicts the directory corruption. I have owned the previous OS 9 Classic version of DiskWarrior 2.1.1, and the OS X version stays true to form (in terms of functionality and ease of use).

I miss the disk optimization program called PlusOptimizer, which is part of the classic version of DiskWarrior. Defragmentation is a desireable feature and would make the DiskWarrior package more complete. It would also be nice if Alsoft provided academic pricing like Symantec does for Norton SystemWorks.

The bottom line, however, it that this utility does wonders for disk repairs and preventative disk maintenance. It completely rebuilds your hard drive's directory, keeps the new directory in memory for preview and cancel options, and provides a fail-safe method for writing the new directory to your disk. DiskWarrior 3 is an indispensable disk repair tool that belongs in every Mac user's toolbox.


  • Rebuilt directory kept in memory with preview and cancel options
  • Fail-safe method of updating the directory to disk
  • Runs native in OS X
  • SMART internal diagnostic routine detects hardware malfunction


  • No SCSI support for SMART diagnostics
  • Can be slow to recover a large volume
  • Does not yet boot in 10.3 (i.e., won't boot on new G5's)
  • Does not include defragmentation

Overall Rating

4 out of 5 Mice