Transcript Chapter 2: Installation Overview

Chapter 2: Installation
Overview
Part 1
• Installing Fedora/RHEL is the process of
copying operating system files from media to
the local system and setting up configuration
files so Linux runs properly on the hardware.
• You can install Linux from many types of
media: including a CD/DVD, the local hard
disk, a USB flash drive, or a hard disk on
another system that is accessed over a
network.
• Several types of installations are possible,
including fresh installations, upgrades from
older versions of Fedora/RHEL, dual-boot
installations, and virtual machine installations.
• You can perform the installation manually or
set up Kickstart to install Fedora/RHEL
automatically.
The Desktop Live CD and the Install
DVD
• Live CD: the Fedora Desktop Live Media
• A live CD runs Fedora without installing it on
the system.
• When you boot from this CD, it brings up a
GNOME/KDE desktop: You are running a live
session.
• You can install Fedora from a live session. Red
Hat Enterprise Linux does not provide a live
session.
The Desktop Live CD and the Install
DVD
• An install DVD does not bring up a desktop
before you install Fedora/RHEL.
• When you boot an install DVD, it brings up a
menu that allows you to install Fedora/RHEL.
The Desktop Live CD and the Install
DVD
• The Net Boot CD (formerly the Boot CD)
boots a system and displays the same menu as
an install DVD (above).
• It does not hold the software packages
needed to install Fedora/RHEL but does allow
you to install a new system from a hard disk or
over a network.
Planning the Installation
Considerations
• SELinux (Security Enhanced Linux) improves system
security by implementing mandatory access control
policies in the Fedora/RHEL kernel .
• By default, Fedora installs SELinux in Enforcing mode.
• If you do not plan to use SELinux, you can change it to
Permissive mode once the system is installed.
• When you install RHEL, if you plan to use SELinux under
RHEL, allow it to remain in Enforcing mode, or change
it to Permissive mode, but do not disable it during
Firstboot.
Considerations
• GUI: On most installations (except for servers),
you will probably want to install a graphical
desktop environment.
• GNOME is installed by default. You can also install
KDE or both GNOME and KDE.
• On a server, you normally dedicate as many
resources to the server as possible and few
resources to anything not required by the server.
For this reason, dedicated servers rarely include a
graphical interface.
Requirements
• Hardware: Fedora/RHEL can run on many
different types of hardware.
• On 32-bit Intel and compatible platforms such as
AMD and VIA as well as 64-bit platforms such as
AMD64 processors , Intel processors with Intel
Extended Memory 64 Technology (EM64T)
including the Core and Core 2 series, and Intel
Itanium (IA-64) processors.
• Fedora/RHEL usually runs on the same systems
that Windows runs on, unless the system includes
a very new or unusual component.
Requirements
• Memory (RAM): You need a minimum of 128
megabytes of RAM for a 32-bit x86 system that
runs in text mode (no GUI) and 192–256
megabytes for a graphical system.
• For a 64-bit x86_64 system, you need at least 256
megabytes for text mode and 384–512
megabytes for a graphical system.
• Linux makes good use of extra memory: The
more memory a system has, the faster it will run.
Requirements
• CPU: Fedora requires a minimum of a 200megahertz Pentium-class processor or the
equivalent AMD or other processor for textual
mode.
• Fedora graphical mode and RHEL require at
least a 400-megahertz Pentium Pro or
Pentium II processor or the equivalent.
Requirements
• Hard disk space: The amount of hard disk
space you need depends on which version of
Fedora/RHEL you install, which packages you
install, how many languages you install, and
how much space you need for user data (your
files).
• The operating system can occupy from about
300 megabytes to more than 9 gigabytes.
Requirements
• BIOS: Modern computers can be set to boot
from a CD/DVD, floppy diskette, hard disk,or
USB flash drive, and from the network via a
PXE server.
• The BIOS determines the order in which the
system tries to boot from each device.
• You may need to change this order: Make sure
the BIOS is set up to try booting first from the
device you are using.
Requirements
• CMOS: is the persistent memory that stores
system configuration information.
• To change the BIOS setup, you need to edit
the information stored in CMOS.
Interfaces: Installer and Installed
System
• A textual interface, also called a commandline interface (CLI) or character-based
interface, displays characters and some simple
graphical symbols.
• It is line oriented; you give it instructions using
a keyboard only.
Interfaces: Installer and Installed
System
• A pseudographical interface, sometimes
referred to as a textual user interface (TUI).
• Takes advantage of graphical elements on a textbased display device such as a terminal.
• It may also use color. This interface uses text
elements, including simple graphical symbols, to
draw rudimentary boxes that emulate GUI
windows and buttons.
• The TAB key frequently moves the cursor from
one element to the next and the RETURN or
SPACE key selects the element the cursor is on;
you give it instructions using a keyboard only.
Interfaces: Installer and Installed
System
• A graphical user interface (GUI) typically
displays a desktop (such as GNOME or KDE)
and windows; you give it instructions using a
mouse and keyboard.
• You can run a textual interface within a GUI by
opening a terminal emulator window.
• A GUI uses more computer resources (CPU
time and memory) than a textual interface
does.
Interfaces: Installer and Installed
System
• Installer interface: Fedora/RHEL provides a
user-friendly, graphical installer interface and
an efficient, pseudographical installer
interface.
• Both interfaces accomplish the same task:
They enable you to tell the installer how you
want it to configure Fedora/RHEL.
• The pseudographical interface gives you fewer
choices.
Fedora or Red Hat Enterprise Linux?
Fedora
• The Fedora Project is sponsored by Red Hat and
supported by the open-source community.
• Fedora Linux distribution incorporates cuttingedge code.
• It is not recommended for production
environments where the set of software packages
and features must remain constant over a longer
period of time.
• It is widely regarded as the most stable “free”
Linux distribution.
Fedora or Red Hat Enterprise Linux?
RHEL
• It is more stable but less cutting edge than Fedora.
RHEL provides at least 7 years of updates; Fedora
provides 13 months.
• Red Hat Enterprise Linux and Red Hat Enterprise Linux
Advanced Platform function identically and are
designed to run servers.
• Red Hat Enterprise Linux is licensed for systems with
one or two physical CPU chips and up to four virtual
guests.
• Red Hat Enterprise Linux Advanced is licensed for
systems with any number of CPU chips and virtual
guests.
Upgrading an Existing Fedora/RHEL
System
• An upgrade replaces the Linux kernel and utilities on an
already-installed version of Fedora/RHEL with newer
versions.
• During an upgrade, the installation program attempts
to preserve both system and user data files.
• An upgrade brings utilities that are present in the old
version up-to-date but does not install new utilities
except as needed to satisfy dependencies (you can
install them later if you like).
• Existing, modified configuration files are preserved;
new ones are added with a .rpmnew filename
extension.
• A log of the upgrade is kept in /root/upgrade.log.
Upgrading an Existing Fedora/RHEL
System
• Clean install: An installation writes all fresh
data to a hard disk.
• The installation program overwrites all system
programs and data as well as the kernel.
• You can preserve some user data during an
installation depending on where it is located
and how you format/partition the hard disk.
Setting Up the Hard Disk
• Low-level formatting is the first step in preparing
a disk for use (this is done at the factory.)
• Second, write a partition table to it and to create
partitions on the disk.
• Finally, you need to create file systems on the
partitions. The area of the disk not occupied by
partitions is called free space.
• Under DOS/Windows, the term formatting means
creating a filesystem on a partition.
Setting Up the Hard Disk
• A partition, or slice, is a logical section of a
hard disk that has a device name, such as
/dev/sda1, so you can refer to it separately
from other sections.
• For normal use, you must create at least one
partition on a hard disk.
• After you install Fedora/RHEL, you can use the
palimpsest disk utility to view, resize, and
create partitions on an existing system.
Setting Up the Hard Disk
• A partition table holds information about the
partitions on a hard disk.
• Before the first partition can be created on a disk,
the program creating the partition must set up an
empty partition table on the disk.
• As partitions are added, removed, and modified,
information about these changes is recorded in
the partition table.
• If you remove the partition table, you can no
longer access information on the disk except by
extraordinary means.
Setting Up the Hard Disk
• Filesystem: Before most programs can write to a
partition, a data structure, called a filesystem,
needs to be written to the partition.
• This data structure holds inodes that map
locations on the disk that store files to the names
of the files.
• When the Fedora/RHEL installer creates a
partition, it also automatically writes a filesystem
to the partition.
• You can use the mkfs (make filesystem) utility,
which is similar to the DOS/Windows format
utility, to manually create a filesystem on a
partition.
The Linux Filesystem
Setting Up the Hard Disk
Primary, Extended, and Logical Partitions
• You can divide a disk into a maximum of 15
partitions.
• You can use each partition independently for
swap devices, filesystems, databases, other
resources, and even other operating systems.
• At most, a disk can hold four primary partitions.
• You can divide one (and only one) of these
primary partitions into multiple logical partitions
• This divided primary partition is called an
extended partition.
Setting Up the Hard Disk
• Absolute pathnames: All files on a Linux
system, including directories, have a unique
identifier called an absolute pathname.
• An absolute pathname traces a path through
the directory hierarchy starting at the root
directory and ending at the file or directory
identified by the pathname.
Setting Up the Hard Disk
• Mounting Point:
• A filesystem on a partition holds no
information about where it will be mounted in
the directory hierarchy.
• You can mount a filesystem on any directory in
the directory hierarchy (in installation
process).
• The directory that you mount a filesystem on
is called a mount point.