Alsoft DiskWarrior - 4.0 Instruction Manual

DiskWarrior

™

Alsoft, Inc.

PO Box 927

Spring, TX 77383

Sales: 281-353-4090, Fax: [phone]

E-Mail: [e-mail]

Support: 281-353-1510

E-Mail: [e-mail]

World Wide Web: www.Alsoft.com

Copyright

This manual and the software described in it are copyrighted with all rights reserved. Under the
copyright laws, this manual or the software may not be copied, in whole or part, without written
consent of Alsoft, Inc., except in the normal use of the software or to make a backup copy. The
same proprietary and copyright notices must be affixed to any permitted copies as were affixed
to the original. This exception does not allow copies to be made for others, whether or not sold
to another person. Under the law, copying includes translating into another language or format.

Limited Warranty

Alsoft warrants the program to perform substantially in accordance with the manual and the disk
on which the program is recorded to be free from defects in materials and faulty workmanship
under normal use and service for a period of ninety (90) days from the date the program is pur­chased. If, during the 90-day period, a defect in the program or the disk should occur, Alsoft will
replace the disk and the program at no charge to you, provided you return the disk with proof
of purchase to Alsoft. Alsoft’s entire liability and your exclusive remedy shall be replacement of
the disk and its contents as provided above. If failure of the disk has resulted from accident,
abuse or misapplication of the disk, then Alsoft shall have no responsibility to replace the disk
under the terms of this limited warranty.

All implied warranties on the program and the disk, including implied warranties of merchant­ability and fitness for a particular purpose, are limited in duration to ninety (90) days from the
date of the original retail purchase of this product.

IN NO EVENT SHALL ALSOFT NOR ANYONE ELSE WHO HAS BEEN INVOLVED IN THE CREATION,
PRODUCTION, DELIVERY, OR SUPPORT OF THE PROGRAM OR THIS MANUAL BE LIABLE FOR
ANY DIRECT, INDIRECT, SPECIAL, CONSEQUENTIAL, OR INCIDENTAL DAMAGES ARISING OUT
OF THE USE, THE RESULTS OF USE, OR INABILITY TO USE THE PROGRAM OR MANUAL EVEN IF
ALSOFT HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES OR CLAIM. In particular,
Alsoft shall have no liability for any programs or data used with the program, including the costs
of recovering such programs or data.

©1998 - 2006 by Alsoft, Inc. All rights reserved. Alsoft, DiskWarrior, DiskExpress and
MasterJuggler are registered trademarks and PlusMaker, and PlusOptimizer are
trademarks of Alsoft, Inc. All other names are trademarks of their respective companies.
Portions of the software ©2003-2006 Apple Computer, Inc.

ii

DiskWarrior Credits

DiskWarrior written by

Al Dion
Rusty Little
Steve Clarner
Brian Webster

Manual written by

Al Dion
Stephanie Jones
Rusty Little
Joe Muscara
Ron Davis

: iii

Table of Contents

Chapter 1: Introduction

Welcome to DiskWarrior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

Alsoft, the Utility Company . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

What Is DiskWarrior? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7

What Is the Directory? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

What Is Directory Damage and How Does It Affect Me? . . . . . . . . . . . . . . . . . . . . . .8

How Does Directory Damage Occur? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9

When Should I Rebuild My Directory with DiskWarrior? . . . . . . . . . . . . . . . . . . . .10

What Is Directory Optimization? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Why Alsoft DiskWarrior Is the Only Answer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

We Put the State-of-the-Art Technologies You Expect from Alsoft in DiskWarrior 13

Basic Terms You Need To Know . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14

Chapter 2: Using DiskWarrior

Installation of DiskWarrior. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Copyright Notice. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

Before You Install. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19

If You Received DiskWarrior Electronically. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

If You Received DiskWarrior on a Disc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Installing DiskWarrior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20

Uninstalling DiskWarrior. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Opening DiskWarrior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21

Quitting DiskWarrior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22

Running DiskWarrior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

Rebuilding Your HFS and HFS Plus Disks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .23

What to Look for in the DiskWarrior Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28

What to Look for During Preview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29

Previewing When the DiskWarrior Disc Is the Startup Disk . . . . . . . . . . . . . . . . . .29

Previewing When the DiskWarrior Disc Is Not the Startup Disk. . . . . . . . . . . . . . .31

Advanced Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33

DiskWarrior Shortcuts - AppleScripting and Drag and Drop. . . . . . . . . . . . . . . . . . . . . . . . . .34

Strategies for Rebuilding with DiskWarrior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35

Using DiskWarrior as Preventative Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . .35

Using DiskWarrior When There Seems to Be a Problem. . . . . . . . . . . . . . . . . . . . .35

Using DiskWarrior to Recover Data from Malfunctioning Disks . . . . . . . . . . . . . .36

What to Do If Your Computer Has a Malfunctioning Internal Disk. . . . . . . . . . . .36

What to Do If You Used Another Utility First . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36

Graphing a Disk Directory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .38

iv

About DiskWarrior’s Directory Optimization Graph . . . . . . . . . . . . . . . . . . . . . . . .40

Graphing a Disk . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40

Understanding the Graph . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41

Using DiskWarrior’s File Checking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .43

Using DiskWarrior’s Hardware Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45

About DiskWarrior’s Hardware Monitoring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46

Manual Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46

Automatic Diagnostics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47

Chapter 3: Troubleshooting and Error Messages

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .50

Disk Status Messages. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52

v

Chapter 1

Introduction

Welcome to DiskWarrior

Alsoft, the Utility Company

At Alsoft, we have been writing software for Mac OS computers since 1984. We are a Macintosh
only software company whose expertise is in providing powerful, useful and safe utilities that
enhance the user experience while maintaining the ease-of-use Macintosh owners have come to
expect. Some of these utilities include DiskExpress®, MasterJuggler®, PlusMaker™, and
PlusOptimizer™.

When we introduced DiskExpress in 1986, it was the first and only disk optimizer for the
Macintosh. Our MasterJuggler Pro is the most comprehensive font management utility package
on the market today. With the release of Mac OS 8.1 in January 1998, Apple introduced their new
disk format for Mac OS computers, known as Mac OS Extended format or HFS Plus.
Simultaneously, Alsoft introduced PlusMaker to let you effortlessly convert your older HFS disks
to the new format. Later that year when Alsoft shipped PlusOptimizer, it was the first disk
optimizer compatible with Mac OS 8.1 and HFS Plus. You can expect to find the safest and most
powerful disk directory damage elimination utility for Mac OS computers only from Alsoft.
DiskWarrior has won more awards than any other disk utility and is recommended as the first
choice of Mac experts everywhere.

What Is DiskWarrior?

DiskWarrior is a utility designed from the ground up with a totally different approach to resolving
directory damage. DiskWarrior resolves 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 bit maps, catalog trees, and extents trees.

Welcome to DiskWarrior

Chapter 1: Introduction 7

This approach has a significant advantage that other utilities 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, then give up when they realize 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.

Hardware failure presents another potential threat to your data. When a drive mechanism fails,
the data on the drive can be lost, with an expensive data recovery service your only option to
retrieve your data. DiskWarrior can be configured to automatically check your drives for
possible drive malfunction, giving you the opportunity to back up your data before a drive failure.

What Is the Directory?

The directory is an area of a disk used by the Mac OS to “map” all the information stored on the
disk. Some of the information stored in the directory are the numbers, names, locations, types,
and sizes of files and folders saved on the disk. When any software wants information from a disk,
the Mac OS must go to the directory to find out where the information is located. Also, when any
software wants to save information to a disk, the Mac OS must go to the directory to find out
where the information can be placed. All the necessary information about where the data was
saved is then recorded in the directory.

The directory has two components, the data and the structure. The directory data is the
information the directory contains, such as the numbers, names, locations, and sizes of files and
folders saved on the disk. The directory structure is the organization of this data in the directory.
The Mac OS uses the structure to quickly access the data and thus find out where in the directory
the data is located. (The directory structure is not the folder organization you see on your disk,
nor is it organized as such.) This structure can be thought of as analogous to a telephone
directory, where the data are the names and phone numbers, and the structure can vary
depending upon which method for finding the data is more convenient. The names and numbers
can be organized alphabetically or by category (automotive, computers, physicians, etc.).

What Is Directory Damage and How Does It Affect Me?

When any of the information about the numbers, names, locations or sizes of files and folders in
a directory (the directory data) or the structure of a directory is either incorrectly updated or

Welcome to DiskWarrior

Chapter 1: Introduction 8

not updated at all, that directory is considered damaged. This damage is normally limited to only
a specific area of the directory. Therefore, it’s quite common for directory damage to remain
undetected until long after the damage actually occurred. Also, if any portion of the directory is
overwritten by an errant program that inadvertently writes its own data, the directory is damaged.

When the Mac OS attempts to use the incorrect directory information to read or write
information on a disk, an error will occur. This error may be very minor and go unnoticed. It
might cause a kernel panic or crash. Or, worst of all, the entire contents of your disk could
become inaccessible.

Note:

Many people mistakenly think that the invisible Desktop files are a part of the
directory. They are not. The truth is that the Desktop files are maintained by the Finder. They
contain a list of your applications and the folders in which they are located (for quick
opening), and the icons and “Get Info” comments of all files. DiskWarrior does not “check”
or rebuild the contents of the Desktop files. Rebuilding the Desktop files will not repair any
directory damage and may even worsen any existing damage.

How Does Directory Damage Occur?

The continued accuracy of information in the directory depends on the ability of the Mac OS to
perform ALL of its update and maintenance operations without any unexpected interruptions.
Also, to help speed up many Mac OS 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 Mac OS computer off without using the proper “Shut Down” procedure,
and pressing the “RESET” button. 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.

Welcome to DiskWarrior

Chapter 1: Introduction 9

When Should I Rebuild My Directory with DiskWarrior?

Obviously, you should run DiskWarrior when you suspect that there is directory damage on one
of your disks. Directory damage can result in the disk not mounting (not appearing on the
Desktop when the computer is started), missing files or folders, or crashes when files are used.
You will also find DiskWarrior useful when another program reports directory damage.

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.
Alsoft recommends that you run DiskWarrior once a 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. You will find doing this regular maintenance of your directories more useful than
rebuilding your Desktop.

What Is Directory Optimization?

In a directory, there is a logical order and a physical order of the file and folder information that
is stored. The logical order is based on the name of the files and the creation order of folders.
The physical order depends upon the available free space on the disk and space within the
directory made available as files are deleted and added. Creating and deleting files makes the
physical order less like the logical order as files and folders are added to the directory where
space is available. Directory searches are performed using the logical order of the directory. As
the physical order becomes less like the logical order, the drive mechanism must move more to
follow the logical order.

Nearly everything uses a search based upon logical order to find files, including Spotlight, the
Finder, applications that search for their preference files, applications that build font menus, and
open dialogs. DiskWarrior optimizes the directory, improving the speed of all of these activities
and many more. Other programs may not provide the true directory optimization provided by
DiskWarrior.

Welcome to DiskWarrior

Chapter 1: Introduction 10

Why Alsoft DiskWarrior Is the Only Answer

When you use DiskWarrior to rebuild your directory, it focuses on what you care most about on
your disk -- your data as it is stored in your files. DiskWarrior rebuilds your directory based upon
the data it finds in the original directory. If you have journaling enabled, the journal file may also
be used. DiskWarrior then uses this information to build an entirely new replacement directory
structure. This approach is similar to that taken by FileMaker with its databases and the Finder
with Desktop files. If you crash or otherwise close a FileMaker database improperly, the next time
you open that database, the first thing FileMaker does is rebuild the database indexes (the
database structure) using the data in the database. When you rebuild your Desktop, you are
rebuilding the structure of the Desktop database. DiskWarrior takes these processes a step
further. When directory data is severely damaged, DiskWarrior scavenges the directory, finding
all the salvageable data. It then uses this data to build a new error-free replacement directory,
recovering lost files and folders as well as making it possible for the disk to appear on the
Desktop.

When other utilities attempt to repair your directory, they attempt to do so by “patching” the
directory structure. 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 of this, you should always use
DiskWarrior first when you suspect directory damage on your disk. Otherwise, you risk losing
directory data (and thus access to your files). Successful directory rebuilding, repair, and
recovery by DiskWarrior is based on the quality of the directory data present.

If you have used another utility to repair your directory and you now have a directory with no
errors but missing data, you can make DiskWarrior scavenge the directory to find the lost data.
This is the same scavenge procedure DiskWarrior uses to recover your data when it finds
directory errors, but it normally skips the scavenge procedure when the directory has no major
errors.

With DiskWarrior, there is never a risk of losing directory data and thus never a risk of losing
access to your files. DiskWarrior uniquely verifies the replacement directory before it can be
written to disk to ensure that it is completely error-free. This also ensures that the disk will have
no problems when rebuilding is complete.

DiskWarrior compares the original directory with the replacement directory and determines if
there have been any changes to the number or contents of your files and folders. It then lists any
differences found in the DiskWarrior Report. You'll know right away what files and folders are
affected by directory damage. You can use this information to see what items you need to test or

Welcome to DiskWarrior

Chapter 1: Introduction 11

inspect in Preview.

DiskWarrior’s patented Preview feature lets you examine your disk as it will appear after the
directory is rebuilt, but before any directory changes are written to disk. You can use the results
of the comparison shown in the DiskWarrior Report to find out which files and folders you
should inspect first because they may have been affected by directory damage. This assures you
that you will get the expected results before any changes are made permanent.

Even though they are not part of the directory, DiskWarrior will also perform other checks. It will
repair damaged boot blocks and rebless the System folder if it is necessary to do so on your disk.
This ensures that your disk will properly start your Mac OS computer once the rebuilding is
complete.

DiskWarrior also checks pre-Mac OS X System and Finder files for damage, eliminates a
common cause of system crashes by checking custom icon files for corruption, and repairs
wrapper System file damage, allowing Macs with these disks to start up properly.

DiskWarrior also checks and repairs OSX User permissions and it checks special files internal
formats.

Welcome to DiskWarrior

Chapter 1: Introduction 12

DiskWarrior can be used to activate internal diagnostics that are built into disk devices to help
determine if a drive is in danger of physical malfunction. These tests can be executed manually,
or you can choose to have the tests run automatically every day, week or month. DiskWarrior
also provides several notification options should the diagnostics report a problem.

We Put the State-of-the-Art Technologies You Expect from Alsoft in
DiskWarrior

• 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 lost files and folders

• 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

• Preview feature to view what the disk will look like after the directory is rebuilt, allowing
you to test files, folders, and applications 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 (Mac OS X 10.2.2 or later)

• Repairs Mac OS User permissions

• Checks special system files internal format

Welcome to DiskWarrior

Chapter 1: Introduction 13

Basic Terms You Need To Know

This section explains some terms and concepts used throughout this manual.

Application

An application is a tool your computer uses to manipulate information and perform a
useful function for you. Applications include such products as AppleWorks, iTunes, or
Mail.

Block

The physical surface of a disk is comprised of many 512 byte storage areas called
physical blocks. The larger the disk, the greater the number of physical blocks on the
disk. An allocation block is a group of one or more physical blocks treated as a single
storage area by the Mac OS. The older Mac OS Standard format, or HFS, can only keep
track of 65,535 allocation blocks per disk. Therefore, the larger the size of a disk, the
greater the number of physical blocks in each allocation block, so that the total
number of storage areas on the disk does not exceed the maximum of 65,535. The
newer Mac OS Extended format, or HFS Plus, can keep track of over 4 billion allocation
blocks per disk. HFS Plus uses allocation blocks sizes ranging from 0.5 KB to 4 KB. The
Macintosh filing system stores files by breaking them into allocation block-size pieces
and writing them into unused allocation blocks wherever they are available.

Damaged Items Folder

When DiskWarrior performs its directory rebuild function, it may recover files that
potentially have problems due to directory damage that existed before the application
was run. If such files are recovered, DiskWarrior will create a Damaged Items folder
for these files.

Directory

The directory of a disk is a group of allocation blocks set aside by the Mac OS to store
the number, name, location (which allocation blocks), and size of each file and folder
stored on the volume.

Directory Data

The directory data includes the information about the numbers, names, locations,
types, and sizes of files and folders saved on the disk.

Directory Structure

The directory structure is how the directory data is organized within the directory. The
Mac OS uses the directory structure to quickly access the directory data. Its structure
is an indexed database, similar to that used by the Finder in the Desktop database, as
well as by FileMaker with its databases.

Basic Terms You Need To Know

Chapter 1: Introduction 14

Disk

A disk is the medium on which information is stored. There are many types of disks
including floppy disks, hard disks (like the one that is probably inside your Mac OS
computer), and removable disks. A disk must be initialized before it can be used.

Document

A document is a type of file you create with an application. Documents include the
information you enter, modify, view, or save to a disk.

Driver

A driver is the software that translates requests from the Mac OS into the commands
the disk hardware itself understands. It is usually supplied by the vendor of the disk
drive mechanism. In the case of the internal disk supplied with your Macintosh, Apple
provides the driver.

Eligible Disk

To be eligible to be rebuilt by DiskWarrior, a disk must have been formatted as a Mac
OS Standard (HFS) or Mac OS Extended (HFS Plus) disk. In addition, an eligible disk
must be locally attached to a computer on which DiskWarrior is running, and it must
not be write protected. The disk must have a valid partition map.

Note:

A copy of DiskWarrior running on your computer will not rebuild any disk that you
must access via a network. These disks are only eligible to another copy of DiskWarrior
running on the computer to which they are locally connected.

File

A file is a collection of information stored on a disk. Files can be system files,
application files or document files.

File Server

A file server is an application designed to allow many users to share common files via
a network.

Free Space

The free space encompasses all the unused allocation blocks on a disk. As free space,
these blocks are available to be allocated to files or to the directory. Once a file is
deleted, the blocks previously occupied by the file will be returned to the free space.
Free space is said to be

contiguous

other on the disk, with no used allocation blocks between them.

Mac OS X System Disk

A disk that contains the files and information necessary to run Mac OS X.

Basic Terms You Need To Know

if the unused allocation blocks are next to each

Chapter 1: Introduction 15

Partition

Apple’s Disk Utility application allows you to divide a disk into parts with appear as
additional disks called partitions. There is also third party software which allows you
to partition a disk.

Partition Map

The partition map is a section of the disk that contains the information for each
partition on the disk. Most Mac OS disks are set up as one partition, but if you set up
your disk as multiple partitions, each partition will behave as a separate disk. For
example, each partition can be unmounted individually, and files dragged between
partitions will be copied instead of moved.

Preview Disk

When DiskWarrior is used to rebuild a directory, the application creates a replacement
directory in memory. When you activate the Preview Mode, DiskWarrior uses its
replacement directory to create a preview disk, allowing you to see the results of the
rebuild before any changes are made. The preview disk is locked; you may copy files
from the preview disk to another disk, but the preview disk itself cannot be modified.

Rescued Items Folder

When DiskWarrior performs its directory rebuild function, it may recover files and
folders for which an enclosing folder could not be found. DiskWarrior will create a
Rescued Items folder for such items. Contents of this folder should be inspected for
damage and may need to have new enclosing folders created, the associated
application may need to be reinstalled, or the items may need to be discarded.

Root Level

The root level of a disk is the starting level of the disk. When you double-click a disk
icon on the Desktop, the window that opens shows you all of the files and folders at the
root level of that disk.

Shared Disk

A shared disk is one that can be seen, or “shared,” by multiple computers over a
network.

Startup Disk

The startup disk is the disk which contains the current operating system of the
computer.

Basic Terms You Need To Know

Chapter 1: Introduction 16