DiskWarrior is a utility program designed from the ground up with a totally different approach to preventing and resolving directory damage which is the leading cause of Mac instability.

DiskWarrior resolves existing disk damage by rebuilding your disk directory using data recovered from the original directory, thereby recovering files and folders that you thought were lost. The directories DiskWarrior creates are also optimized for maximum directory performance.

DiskWarrior is not a disk repair program in the conventional sense. It does not attempt to solve all of the possible problems that can occur with a disk. It specializes in eliminating directory errors - the most common problems Mac OS users have with their disks.

DiskWarrior rebuilds your disk directories making them error-free, eliminating any problems the errors would have caused, and recovering lost files.

It fixes any problem with master directory blocks and alternate master directory blocks (HFS), volume headers and alternate volume headers (HFS Plus), volume bitmaps, catalog trees, and extents trees.

This approach has a significant advantage that the others overlook. Other products attempt to repair your directory one step at a time, ignoring the big picture of what is truly wrong with your directory, and risking file information that could be saved. Too often, they will incorrectly begin to "repair" your directory, and then give up when they realize that they have modified the directory to an irreparable state. At Alsoft, we know that the most important thing when you are attempting to repair your disks is getting your data back. That's why the first thing DiskWarrior checks is your directory data, and that's what it uses to create a replacement directory. DiskWarrior continues its rebuild operations unless no directory data can be found.

Directory damage isn't the only threat to your data. A physical hardware malfunction can cause intermittent loss of access to any data on the drive. If the malfunction is serious enough, the only way to retrieve the data on the drive is through an expensive data recovery service. DiskWarrior can be configured to automatically check drives for possible drive malfunction, giving you the chance to back up your data before a drive completely fails. The hardware monitoring can also be run manually if you suspect a drive malfunction.

Alsoft has been making disk utilities for the Mac over 25 years. Our disk optimization utilities have always chosen the safety and security of your data over anything else, and have been able to detect and report directory errors no other program can (the others obviously couldn't fix the problems they couldn't even find). That knowledge has been put into DiskWarrior to give you the only tool that can eliminate all directory problems and recover files and folders! And, as an added bonus, the directory DiskWarrior creates is optimized for maximum speed when accessing your files!

When other utilities attempt to repair your directory, they attempt to do so by "patching" the directory one problem at a time, ignoring the big picture of what is truly wrong with your directory and risking file information that might otherwise have been saved. This method can result in sections of the directory being patched over and deleted. Since whole sections of the directory can be deleted, this attempt at repair can cause loss of directory data and thus loss of access to your files.

Because other utilities may delete directory data in their repair attempts, you should always use DiskWarrior first when you suspect directory damage on your disk. DiskWarrior uses a unique method of quickly rebuilding your directory from the data recovered in your old directory.

This method recovers files and folders that you thought were lost and that no other program can recover. Otherwise, you risk losing directory data and thus access to your files. With DiskWarrior, there is never a risk of losing directory data and thus never a risk of losing access to your files.

The best use of DiskWarrior is for preventative maintenance of your disks. Many forms of directory damage do not manifest themselves until long after the damage has actually occurred.

You can prevent this damage from escalating by running DiskWarrior on your disks regularly - we suggest at least once each month. DiskWarrior will rebuild your disk directory, eliminating all existing directory damage. The directory DiskWarrior creates is also optimized for maximum directory performance, and this will speed up the performance of your disk.

Obviously, you should run DiskWarrior when you suspect that there is directory damage on one of your disks. Directory damage can result in a disk not mounting (not appearing on the desktop when the computer is started), missing files or folders, an inability to move or copy files, or crashes when files are used. 

Finally, you should run DiskWarrior if your Mac explicitly warns you of a problem with your disk in the form of an error message. Most of these errors are reported by the built-in Disk Utility whether your OS X version is 10.5 Leopard, 10.6 Snow Leopard, 10.7 Lion, 10.8 Mountain Lion, 10.9 Mavericks, 10.10 Yosemite, 10.11 El Capitan, 10.12 Sierra, 10.13 High Sierra or 10.14 Mojave. Here are some of the most common messages:

• Disk Repair: The disk was not repairable by this computer. It is being made available to you with limited functionality. You must back up your data and reformat the disk as soon as possible.

• The underlying task reported failure on exit.

• Invalid node structure.

• Keys out of order.

• Invalid key length.

• Invalid directory item count.

• Invalid extent entry.

• Invalid record count.

• Invalid index key.

• Invalid sibling link.

• Missing thread record.

• Invalid B-tree node size.

• Invalid leaf record count.

• Invalid volume file count.

• Invalid volume directory count.

• Invalid volume free block count.

• Invalid volume header.

• Volume header needs minor repair.

• Volume bitmap needs minor repair.

• Incorrect number of thread records.

• Incorrect number of extended attributes.

• Incorrect number of Access Control Lists.

• Unused node is not erased.

These messages are less common:

• Invalid node height.

• Incorrect block count for file.

• Overlapped extent allocation.

• Invalid number of allocation blocks.

• Invalid BTH length.

• Overlapped node allocation.

• Invalid catalog record type.

• Invalid catalog PEOF.

• Invalid extent file PEOF.

• Invalid B-tree header.

• Catalog file entry not found for extent.

• Missing directory record.

• Invalid key for thread record.

• Invalid parent CName in thread record.

• Invalid BSD file type.

• Incorrect number of directory hard links.

• Incorrect number of file hard links.

• Invalid finder info for file hard link.

• Incorrect flags for file hard link.

• Orphaned file inode.

These messages occur with the least frequency:

• Missing file record for file thread.

• Invalid root node number.

• Invalid map node.

• Invalid header node.

• Invalid directory record length.

• Invalid catalog record length.

• Invalid file or directory ID found.

• Indirect node needs link count adjustment.

• Incorrect folder count in a directory.

• HasFolderCount flag needs to be set.

• Invalid parent for directory inode.

• Incorrect owner flags for directory hard link.

• Previous ID in a hard link chain is incorrect.

• Next ID in a hard link chain is incorrect.

• Incorrect flags for file inode.

• Invalid first link in hard link chain.

• Orphaned file hard link.

• Incorrect size for file.

The directory is the portion of your disk set aside to record the names and locations of your files and folders. When your directory is either incorrectly updated or not updated at all, your directory is damaged.

If your Mac crashes or loses power, updated directory information that the OS X caches in memory for faster access never gets written to your disk, resulting in directory damage. The presence of directory damage may be very minor and go unnoticed. Or it could make some or all of your files inaccessible!

The continued accuracy of information in the directory depends on the ability of OS X to perform ALL of its update and maintenance operations without any unexpected interruptions. Also, to help speed up many computer operations, important pieces of information are temporarily cached in memory instead of being immediately saved to the disk.

Common types of unexpected interruptions are kernel panics and crashes, power loss (lights flicker), turning your OS X computer off without using the proper "Shut Down" procedure. Depending upon the exact moment of the interruption, you stand a good chance that your directory was either not updated correctly and/or some information had not been saved to the disk. You now have directory damage and/or information loss.

Another way that your directory can be damaged is if an errant program inadvertently writes its own data to the portion of the disk that is reserved for the directory. If this occurs, then your directory data has been overwritten and may be permanently lost. Also, system extensions, called kernel extensions in OS X, may inadvertently corrupt system data. Directory damage occurs when the directory containing the corrupt data is saved to disk.

Your data may be lost when the hard drive containing the data has a mechanical malfunction. As drives are used, their parts begin to wear out. Drive manufacturers have begun including internal diagnostic routines in their drives to help determine if a drive is exceeding its operating tolerances, but unless you have software to access these routines, you will not have any warning of the impending drive malfunction. 

With DiskWarrior installed, you can enable DiskWarrior's hardware monitoring capability, which uses a drive's built-in S.M.A.R.T. technology to monitor drive hardware. If the diagnostics indicate the potential for a malfunction, DiskWarrior provides you with a warning, using the notification method you have specified. This warning gives you the chance to back up any data on the drive before it fails completely, saving you from having to rely upon an expensive data recovery facility to retrieve your data.

DiskWarrior now ships on a flash drive instead of DVD. If you plan to rebuild the directory on your startup (built-in) disk, you need to start up from another disk capable of starting up in OS X 10.5.8 through 10.14, such as the DiskWarrior Recovery flash drive or your Mac's OS X Recovery (the Recovery HD). OS X Recovery is available in OS X 10.7 (Lion) and later.

Whether started from the DiskWarrior Recovery flash drive, OS X Recovery or another disk, DiskWarrior can run from the flash drive to eliminate all damage to any HFS (Mac OS Standard) and HFS Plus (Mac OS Extended) disk directories, including your normal startup disk.

DiskWarrior can repair any Mac formatted disk including RAID volumes, Fusion disks, flash drives, and FileVaults.

DiskWarrior optimizes your directory for maximum performance. Directory optimization typically results in a 50% to 60% decrease in the time it takes programs to scan the directory and as much as a 10% to 20% decrease in startup time. Other programs may not provide the true directory optimization provided by DiskWarrior. 

DiskWarrior compares your old directory with the new rebuilt directory and determines if there have been any changes to the number or contents of your files and folders. It then lists any differences it finds in the DiskWarrior Report. You'll know right away what files and folders are affected by directory damage. The report lists the problems found by file, making it easy for you to see what files and folders you need to check in the preview.

DiskWarrior's patented preview feature lets you examine the files and folders on your damaged disk as they will appear after the directory is repaired but before any changes are made to the disk. This assures you that you will get the expected results before any changes are made permanent.

When enabled, DiskWarrior's hardware monitoring capability can notify you if your drive devices are in danger of failing. This notice can give you valuable warning, allowing you the opportunity to back up your files before the drive becomes completely inaccessible. Without such a back-up, your may be left with an expensive data recovery service as the only way to get your data back.

DiskWarrior verifies your rebuilt directory to ensure that it is error free. For protection from interruptions such as power loss, DiskWarrior uses a unique fail-safe method of replacing the damaged directory with the repaired directory. With DiskWarrior, you never have to worry about the safety of your files.

If there is a system folder on your disk, DiskWarrior will ensure that it is blessed. No more flashing question mark!

DiskWarrior safely rebuilds journaled disks. It also checks System and Finder files for damage, eliminates a common cause of system crashes by checking custom icon files for corruption, and repairs the wrapper volume System files caused when HFS Plus disks are initialized under Mac OS 9.0 - 9.0.4, allowing Macs with these disks to start up.

DiskWarrior is the only program where there is never a risk of losing directory data and thus never a risk of losing access to your files.

Only DiskWarrior has all of these features:

• Universal Binary for Intel and PowerPC Macs

• Repairs invalid file permissions

• Finds corrupted Preference (.plist) files

• Optimizes, repairs and rebuilds FileVaults

• Tests the length of path names for each item on your drive

• Fully supports case-sensitive file names

• Rebuilds Attribute B-trees

• Repairs and rebuilds Access Control Lists (ACLs)

• Repairs Time Machine backups

• Uses directory data to quickly rebuild the directory structure

• Eliminates risk of losing access to files – other disk "repair" utilities attempt to fix the directory by patching the directory structure and risk deleting sections of the directory

• Scavenges directory to find all salvageable file and folder data, even data contained in damaged nodes

• Eliminates unseen directory errors, preventing minor directory errors from escalating into major problems

• Recovers missing files and folders (Not deleted or overwritten files)

• Optimizes directory for maximum directory performance, speeding up overall disk performance

• Monitors drive hardware for potential drive failure

• Verification of replacement directory ensures data integrity

• Comparison of original directory with replacement directory tells you which files and folders may have been affected by directory damage

• Patented preview feature to view what the disk will look like after the directory is rebuilt, allowing you to view files and folders before any directory changes are written to disk

• Repairs damaged boot blocks and blesses the system folder to ensure that the computer will start from the repaired disk

• Checks custom icon files for corruption, eliminating a common cause of system crashes

• Repairs problems with wrapper volume System files caused when HFS Plus disks are initialized under Mac OS 9.0 - 9.0.4

• Safely permits interruptions of any kind, including power outages

• Advanced "Verify Reads and Writes" technology protects your data

• Supports bad block sparing software

• Supports file journaling

DiskWarrior's ability to rebuild your directory and recover lost files and folders is unrivaled. 

DiskWarrior rebuilds your directory based upon the data it finds in the old directory and verifies your rebuilt directory to ensure that it is error free. 

DiskWarrior's patented preview allows you to preview your disk as it will appear after the directory is repaired but before any changes are made to the disk. 

With DiskWarrior, there is never a risk of losing directory data and so there's never a risk of losing access to your files.