Even a modern, memory-protected, and preemptively multitasking operating system such as Mac OS X can't prevent bad things from happening to the data on your hard drive. And when an unfortunate event occurs -- such as a kernel panic that forces you to reboot your machine without shutting down properly -- you want a tool that can downgrade a major disaster to a mere inconvenience. DiskWarrior 3.0, the long-awaited OS X–native version of Alsoft's disk utility, offers Jaguar users repair capabilities and maintenance features that will significantly reduce the likelihood and severity of many drive-related mishaps.

DiskWarrior never harmed any of the volumes it worked on during our testing. This clearly Hippocratic utility does only good for your hard drive's health. DiskWarrior users pondering an upgrade to 3.0 should delay no further.

Holistic Disk Repair

DiskWarrior takes an iconoclastic approach to repairing hard drives. Rather than going through a checklist of problems and fixing them one by one (as other disk utilities, such as Norton Disk Doctor, do), DiskWarrior gathers all the available information about files and folders on the volume; it then uses that information to create a brand-new set of directory data. DiskWarrior compares the original volume to the freshly created directory and tells you if there are differences. This holistic approach has proved itself many times over in DiskWarrior's lifetime.

DiskWarrior's approach has one side effect worth mentioning: if you rely on software utilities to retrieve formerly deleted files, replacing a volume's directory with DiskWarrior's freshly built one will scotch that ability. When rebuilding directories, DiskWarrior also removes any remnants of information about previously deleted files.

The converse is true in one situation: sometimes, a volume's directory is so damaged that DiskWarrior has to build a new directory by piecing together a coherent whole from digital remains, so it may recover files, or their fragments, that have been previously deleted.

DiskWarrior 2.1.1, version 3.0's immediate predecessor, was compatible with OS X–formatted drives, but it didn't run natively in OS X. Even worse, because OS X volumes typically have many more folders and files -- most of them invisible to the casual user -- DiskWarrior 2.1.1 could be excruciatingly slow. But version 3.0 eliminates both of these hurdles. DiskWarrior 3.0 is significantly faster than its ancestor, and it supports HFS, HFS+, and journaled HFS+ volumes. DiskWarrior 2 supported journaled volumes but had the unfortunate side-effect of disabling journaling after it had finished rebuilding the directory.

In our testing, DiskWarrior 3.0 readily found and fixed mild directory problems such as improperly set custom icon bits and incorrect volume bitmaps, and it even handled more-severe hardware-related problems with aplomb. One test disk developed bad sectors in the area occupied by the directory data, a fate that usually spells disaster. DiskWarrior took well over an hour to work its way through the damaged disk, but it did finish, and the newly generated directory allowed us to recover files from the drive. DiskWarrior 3.0 is leaps and bounds faster when rebuilding a directory on a drive with healthy hardware, but it also takes its time and doesn't give up when confronted with hardware errors. This is a major benefit.

SMART and Vigilant

DiskWarrior 3.0 can now query a hard drive as to whether its hardware is hale and hearty. Most mainstream -- not just server-grade -- IDE drives sold over the last few years support SMART (Self-Monitoring, Analysis, and Reporting Technology). SMART-savvy software can ask the drive whether everything is OK. A lot of errors can be an early warning of the impending demise of a drive's hardware. Since DiskWarrior can't fix hardware-related errors, SMART support is a welcome and useful addition. You can schedule DiskWarrior's SMART query to run hourly, daily, or weekly; it will run even when DiskWarrior isn't running. If anything is amiss, DiskWarrior will notify the user via an on-screen or e-mail alert, or it will launch an AppleScript to take a more-complex action such as logging an event in a database.

One missing capability that was in DiskWarrior 2 is DiskShield, an extension that ran in OS 8.1 through 9.X. It made sure directory data was written regularly. (If a crash happened while directory data was waiting in RAM, your disk wouldn't be able to access some of the data it contained.) The DiskShield extension could also detect certain kinds of directory damage and alert the user that it was time to run DiskWarrior. Although the addition of SMART support is welcome, we miss the extension's capabilities.

DiskWarrior 3.0 comes on a bootable OS X CD. Unfortunately, due to Apple's licensing restrictions, you can't distribute a fully functional bootable CD with a Finder on it. Having a Finder available allowed DiskWarrior 2 users to directly compare old and new directories. With DiskWarrior 3.0, Alsoft worked around the Finder limitations by integrating a directory browser that displays a volume's before and after states, thus letting you compare the two. While Alsoft's browser does the job, it's too bad that DiskWarrior's developers had to spend effort developing such a feature when the Finder would've been the ideal solution.

Macworld's Buying Advice

DiskWarrior 3.0 is a tool that any serious Mac user -- and certainly every IT administrator -- should have. Its performance is significantly better than its predecessor's, and the new SMART-based hard-drive monitoring can prevent data loss through early warning. But unlike tools that focus solely on disaster recovery or prevention, DiskWarrior is also a useful maintenance tool that can provide you with peace of mind.