Lion File System.pdf

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OS X Lion: File SystemIntroduction

This course covers the file system principles of the Mac OS. This includes how hard drives (and

devices) are prepared for use with the Mac OS; as well as the levels, folders and files of a volum

Course Overview

Course Objectives

Demonstrate how to prepare a hard drive or mass storage device for use with the Mac OS

Differentiate the root and user level of a volume

Identify associated files and folders associated to root and user levels

Locate and manage Library folders

Determine and resolve common file system issues

What is Storage?

Storage refers to the actual disk drive hardware. Storage comes in all shapes and sizes. Exampl

User Level Structure

When you create a user account, Mac OS X creates a Home folder for that user. The Home folde

your user name) can be found in the root level "Users" folder found at the root level. This folder

Audience

Technicians who wish totroubleshoot and service

Mac computers

Prerequisites

OS X Lion: Basics

Time Required

45 minutes

You wi

OS X LiMac comp

and Intern

OS X Lion: File System

Introduction

Course Overview

What is Storage?

What are Partitions?

Partition Map Schemes

Partition Formats

Partitioning a Disk

Recovery Partition

Root Level Structure

User Level Structure

Library Folders

FileVault 2

Boot Camp

Learning Resources

Contact Us

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accessed by other users.

Each Home folder contains a series of subfolders (also created at the time the user account i

Desktop

It is common and often convenient for users to keep files in this folder, as they appear on the F

(when that user is logged in). When accessed otherwise, such as remotely over a network, deskt

inside this folder.

Documents

This is the default storage location for any user-created document type that does not have a de

Downloads

This folder is the default location for all Internet applications (such as Safari and Mail) to store

files. Sequestering all Internet downloads to this folder also makes it much easier for virus and

protection utilities to identify potentially harmful files.

Movies

This folder is the default location for all movie file, such as those iMovie or iDVD projects.

Music

This folder is the default location for all audio files, such as those in the users iTunes music lib

Pictures

This folder is is the default location for all pictures files, such as those in the user's iPhoto libra

Public

This is the default location for users to share files with others. Everyone who has access to a co

or via network file sharing can view the contents of this folder. There is a Drop Box folder insid

where others can place files that only the owner of the home folder can use.


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Sites

This is the default location for personal websites when Web Sharing is enabled. Outside of viewi

through a web browser, only other local users can actually browse inside this folder. This folde

when doing an upgrade from Snow Leopard to Lion. On a clean install the Sites folder will not a

Where is the user's Library folder?

Starting with OS X Lion, the user's Library folder is deliberately hidden. This w

protect the user from accidently tampering with preference, system or applica

resources.

Note: This folder should not be confused with the root-level library folder. Ea

a different function which will be covered in the next section.

More Hidden Files and Folders

In addition to the user's library folder, select files and folders that support the

not appear in Finder windows. These system support items are exclusively use

X and would only be confusing to ordinary users.

To view these files and folders, go to Finder > Go Menu > Go to Folder, or use

(use the invisible attribute). Although these items should not be moved or del

administrator can make changes to these files.

Note: By default, any file that has a period at the beginning of its name will be

both Finder and Terminal). For example, each user has a separate trash folder,

hidden, and located at /Users/~/.Trash.

Learning Activities

Find out how to access the user Library folder.

(Hint: Mac Help menu > Search: Library folder)

What are Partitions?

Free space on a disk must be partitioned before it can be used. Partitioning a disk erases all the

assigns it a partition scheme, and then divides it into sections, called "volumes." A volume is ho

operating system recognizes the free disk space on a partition. Each volume works like a separ

Volume 1

Volume 2

Volume 3

Hard Drive

Why partition my drive?

You plan to use one volume as the startup disk with applications and worki

other disks as a place to back up or archive files.


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You need different versions of the Mac OS.

You intend to run a compatible version of Microsoft Windows on your MacCamp. (Boot Camp assistant will partition the drive for you.)

FileVault 2

You can use FileVault to protect the files on your disk from being seen or copied. FileVault disk

encodes the information stored on your disk so it cant be read unless the login password is en

If you store sensitive information on your computer, you should consider using FileVault disk e

example, if you carry all your companys financial data on your portable computer, losing it cou

someone to access sensitive data that might hurt your business. If you are logged out of your a

your computer is lost but the data is encrypted, your information is protected.

The disk encryption in Mac OS X uses the government-approved encryption standard, the Adva

Encryption Standard with 128-bit keys (AES-128).

FileVault 2 is managed via the Security & Privacy preference in System Preferences. Click the Fil

the Security & Privacy preferences and you can enable or disable FileVault.

If your Mac has multiple user accounts, you will be asked to identify the user accounts that will

unlock the encrypted drive (to start the computer or recover from sleep or hibernation).


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Users not enabled for FileVault unlock will only be able to log in to that Mac after an unlock-en

started or unlocked the drive. Once unlocked, the drive remains unlocked and available to all u

computer sleeps, hibernates, or is shut down.

Lastly, you are given a recovery key. An administrator can use the recovery key as a safety mea

the disk if the administrators login password is forgotten.

Additional Security Features

To ensure security when you turn on FileVault other security features are also

For example, a password will be required to log in, after waking from sleep, a

leaving the screen saver. After the initial startup only users enabled in FileVaul

to log in, other users will need an administrator to log in first.

Warnings

1. FileVault 2 requires OS X Lion and Recovery HD installed on your startup

receive an alert during installation that no Recovery HD could be created

to install OS X Lion, you will be unable to use FileVault 2.

2. Dont forget your administrator password. If you turn on disk encryption

forget both your login password, your Apple ID, and your recovery key, y

able to log in to your account, and your files and settings are lost forever.

Partition Map Schemes

Partition map schemes define how data is organized on a hard drive. There are three different t

1. GUID (Globally Unique Identifier)


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This is the default partition scheme used by Intel-based Macs. This is also the only partitio

allows Intel-based Macs to start up. Also known as GPT (GUID Partition Table).

2. APM (Apple Partition Map)

Default partition scheme used by PowerPC-based Macs. This is also the only partition sche

PowerPC-based Macs to start up. However, all Intel-based Macs can also access this type o

3. MBR (Master Boot Record)

The default partition scheme used by most non-Mac computers, including Windows-comp

is the default partition scheme you will find on most new pre-formatted storage drives. Eve

Mac can start up from this type of partitioning, all Macs can access this type of partitioning

GUID Partition Table Scheme Required

OS X Lion can only be installed onto internal and external hard drives that use

Partition Table scheme. Use Disk Utility to change the partition scheme.

Partition Formats

Formatting is the act of creating a file system on a volume, so that the operating system can st

data on that volume. Volumes must be formatted with a file system before data can be stored o

1. Mac OS Extended (Journaled)

This is the default volume format for Mac OS X. It is a derivation of the Mac OS Extended foadvanced file system journaling to help preserve volume structure integrity.

A journaled file system logs when files are changed as they are written to storage. The jour

in such a way that it is never compromised should the system become inoperative. This wa

failure or system crash occurs, after the system restarts it will be able to quickly verify the i

volume based on the journal log. Journaling helps improve overall file system stability, and


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chances that files become corrupted over time.

2. Mac OS Extended, Journaled, Case-Sensitive

This volume format adds case-sensitivity to the file system. Normally Mac OS Extended is c

but case-insensitive. This means that a normally formatted Mac volume will remember wh

chose for the characters of a file's name, but it cannot differentiate between similar file na

only difference is the case. In other words, it would not recognize "MYfile" and "myfile" as d

filenames. The Case-Sensitive option would recognize "MYfile" and "myfile" as different file

The case-sensitivity option is normally not used when setting up a Mac for normal Mac OSsensitive file systems are typically only used in situations where file name case sensitivity i

as with legacy UNIX applications and scripts that require (or were only designed for) case s

systems.

3. MS-DOS (FAT)

Used for 32GB or less disks that will be used with a Windows computer.

4. ExFAT

Used for disks larger than 32GB that will be used with a Windows computer.

5. Free Space

Format Recommended by Apple

Apple recommends the Mac OS Extended (Journaled) format when setting up

normal Mac OS X use, for greater reliability. Journaling is recommended for all

computers as a preventative measure against file corruption.

Partitioning a Disk

Partitioning a disk erases all the files on the disk. Be sure to copy any files you want to keep to

before you partition the disk. You can specify the number of partitions and the size of each one

How to Partition a Disk

If youre partitioning an external disk, make sure its connected to your computer, and then go

1. Choose Apple menu > Restart. Hold down the "Command" and "R" keys as your computer r

When you see a white screen with an Apple logo in the middle, you can release the keys.

2. When the Language Chooser appears, select your language and then click the Continue but

an arrow).

3. Run Disk Utility.

4. Select the disk that you want to partition and click Partition.


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5. Choose the number of partitions from the Volume Scheme pop-up menu.

6. Click each partition and type a name for it, choose a format, and type a size. You can also

between the partitions to change their sizes. If a partitions name has an asterisk beside it,

larger than its actual size in order to display its name clearly.

7. If youll be using a partition as a Mac OS X startup disk, click Options, and choose the the

scheme.

8. Click Apply.

Protect an External Disk with a Password

You can protect an external disk or thumb drive with a password, so when yo

disk to your computer, you must enter the password before you can access its

Note: To protect the disk, you must erase it first. If the disk has any files you

be sure to copy them to another disk.

1. Open Disk Utility (Utilities > Disk Utility).

2. Connect the disk to your computer.

3. Select the disk and click Erase.

4. Choose Mac OS Extended (Journaled, Encrypted) from the Format pop-u

5. Type a name for the disk.

6. If you want to prevent the erased files from being recovered, click Securit

the slider to choose how many times to write over the erased data, and cli

7. Click Erase.

8. Enter a password when prompted.


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Choosing a Startup Disk

If you partitioned your disk and installed different operating systems on to the

you change your startup disk by:

Going to System Preferences > Startup Disk. Select the system you wish toor

Holding down the Option key as your restart the Mac. When you see the av

disks, select one.

These two techniques can also be used to startup from a CD, DVD or external

Recovery Partition

OS X Lion introduces the addition of a recovery partition containing help, recovery tools, and ut

partition is automatically created during installation of OS X Lion.

This partition replaces the Mac OS X installation disc from previous versions of Mac OS X. Starti

recovery partition is similar to starting up a Mac from its installation disc.

After successfully starting up from the Recovery HD, you will see a desktop with a Mac OS X me

"Mac OS X Utilities" application window.

Firmware Password Utility, Network Utility, and Terminal can be found and accessed in the Utilit

Where's the Recovery Partition?

The recovery partition will not be displayed in the Finder or in Disk Utility. It is

hidden from the user.

Reformat Deletes Recovery Partition


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If the OS X Lion hard drive (not a volume or partition) is completely reformatte

recovery partition will be lost. However, it will be restored upon the reinstall o

Learning Activity

Startup from the recovery partition on an OS X Lion hard disk. Restart or powe

and select one of the two methods:

Hold down the Command and R keys during startup

Hold down the "Option" key to access the Startup Manager, then select "Re

Note: If FileVault is enabled, Recovery HD will not appear in the Startup MaCommand and R keys to access Recovery HD.

Tip: Familiarize yourself with the tools found in the Mac OS X Utilities men

Root Level Structure

Now that we have covered how a hard drive is prepared for use with an operating system, we wi

at its structure.

Upon installing Mac OS X onto a hard drive (or unboxing a Mac for the first time), you will notic

startup volume is named "Macintosh HD" by default. At the top of the file and folder hierarchy i

level".

The primary folders at the root level are:

Applications

When local users install an application, it will be installed here by default.Inside the Applicatio

folder called "Utilities". It contains specialized applications to help analyze, configure, optimize

the computer.

Library

The root level Library folder contains important support files (such as fonts and preferences) us

and your applications. The files contained here support all local users. This folder should not b

a user's own Library folder. Only administrators can make changes to the contents of this folde


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System

This folder contains resources required by the operating system. It is very rare that any user sh

make changes to the contents of this folder. Administrators must re-authenticate and enter the

make changes to the contents of this folder.

Users

The Users folder houses all the content for each user account on the Mac; each user has a sepa

folder that's named after his or her user account name.

Library Folders

Library folders contain support files used by Mac OS X and your applications (such as fonts, plu

preferences). There are at least three and sometimes four Library folders in a typical Mac OS X i

Each has a slightly different purpose.

1. Root Level Library folder (/Library)

System-wide resources that are not installed by the operating system are added to the /Lib

example, fonts for all users are installed in /Library/Fonts. Any resources placed in this fol

available to all local user accounts. By default, only administrative users can make changes

resources.

2. User Level Library folder (/Users/~/Library)

Since Mac OS X is a multi-user system, each user has separate resources, such as personal

resources are stored in the Library folder found in each users home folder. Resources are

only accessible to that specific user and is not accessible by others. This makes it easy to b

restore all of the documents and preferences for each user.

3. System Library folder (/System/Library)

The system domain encompasses all the items necessary to provide core system functional

example, system fonts needed for core system apps such as the Finder are stored in

/System/Library/Fonts. There are many hidden items at the root of the system volume that

system resource domain, but the only one you will see in the Finder is the root System fold

Library folder within. In most cases, you do not need to add any resources here.

4. Network Library folder (/Library/Network/Library)

This folder does not normally exist in a typical Mac OS X installation. Mac OS X can access

resources and applications from a network file share. Administrators must configure an autshare in order to enable the Network resource domain.

Why all the Library folders?

With up to four different domains containing resources, there is a strong likeli

overlap in resources. In other words, there may be multiple copies of similar r

available to the system and user at any given time. Mac OS X is designed to ha

searching for resources from the most specific location (those in the user dom

the less specific (those in the local domain), and on to the least specific (those

system and network domains).

Example: If multiple versions of a particular font are found (one in the local Li

in the user's Library), the copy in the user's Library will be the one used becau

most specific location.

Segregating resources into multiple domains provides increased administrativ

resource security, and system reliability. Resource domains are more flexible


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a m n strators can c oose to a ocate certa n resources to a users or ust spe

It's more secure because standard (non-administrator) users can only add res

own home folder and cannot access other users' resources. Finally, it's more r

because, in most cases, you don't have to make changes to core system functi

order to provide more services.

Avoid Application Issues

Don't move or change the name of installed folders and applications. If you ch

name of the /Users/~/Library folder, you may lose preference settings for Ma

Mac OS X applications.

In addition, Mac OS X will automatically create a new Library folder. If this hap

want to restore you preferences, drag the new Library folder to the Trash and

old folder "Library."

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