Every Mac volume has a cataloga kind of table of contentsthat the OS uses to find your files. If the catalog becomes badly damaged and you don't have a backup, your data could be lost. Alsoft's DiskWarrior comes to the rescue by repairing mangled catalogs, displaying impressive stability and reliability for a 1.0 release.
DiskWarrior's sole focus is the reconstruction of catalogs, a process that's beneficial for healthy as well as broken catalogs. Unlike Symantec's Norton Disk Doctor, DiskWarrior doesn't examine your disk, run through a checklist of possible errors, and fix them one by one. Instead, DiskWarrior takes a holistic approach: it looks at the existing catalog data, collects additional information the OS has stored elsewhere on the disk, and uses all the information to re-create an entirely new catalog.
By rebuilding a damaged catalog, DiskWarrior can resurrect previously deleted files as well as those believed to be lost. If the catalog is healthy to begin with, rebuilding has a measurable speed benefit because a fresh catalog is much easier to search. On a test volume, the Mac OS's Disk First Aid took 1 minute and 44 seconds to scan the catalog; after rebuilding, it took only 39 seconds. (To rebuild a disk's catalog without DiskWarrior, you'd have to back up, initialize, and restore the disk; simply defragmenting files with a disk optimizer doesn't have the same effect.) And DiskWarrior proved remarkably reliable: not once during testing did the program create a bad catalog or cause any disk-related vexations.
DiskWarrior's user interface is remarkably straightforward. You simply select a disk and press the Rebuild button, and DiskWarrior builds a new catalog. Once it's finished rebuilding, you can preview how your disk will look with the new catalog: DiskWarrior mounts both the original and rebuilt catalogs as read-only disks and lets you explore them in the Finder. You can then use the preview catalog to copy files off the disk, without changing anything on the disk itself. If you decide you want to keep the rebuilt catalog, DiskWarrior uses it to replace the old one.
Only one noticeable flaw appeared during testing: if a disk was damaged in such a way that the Mac OS refused to mount it, DiskWarrior wouldn't work with it.
Although it's not as comprehensive as Norton Disk Doctor, DiskWarrior performs its one crucial function well and should be part of any collection of disk tools. Not only is the program useful for sprucing up healthy disks but it also increases your odds of recovering files that might otherwise be lost.
RATING: PROS: Reliable; foolproof user interface; useful preview feature; speeds up healthy drives. CONS: Can't see some unmountable disks; not as comprehensive as Norton Disk Doctor. COMPANY: Alsoft (281/353-4090, http://www.alsoft.com ). LIST PRICE: $69.95.
April 1999 page: 46