Transcript Lecture 10 Operating System Fundamentals_rev

Lecture 10
Operating System Fundamentals
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Operating System Basics
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Overview of PC Operating Systems
Desktop microcomputers became
popular in the early 1980s.
Users of these PCs put their systems
to work performing a variety of tasks,
including word processing, home
accounting, and computer gaming.
Workplace productivity was limited
by their inability to share information
easily with other systems.
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The Kernel
Kernel is the most common term for the
core of the operating system.
It is a small piece of code that is loaded
into memory when the computer boots.
The kernel manages and controls memory
allocation, system processes, and other
programs.
Application software and other parts of the
operating system rely on the kernel to
provide basic scheduling services and
access to the computer hardware and
peripherals.
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The User Interface (UI)
The UI is the component of the OS that the
user interacts with.
The UI is like an interpreter, translating user
keystrokes, mouse clicks, or other input for
the appropriate programs.
A graphic user interface (GUI) allows the
user to manipulate software using visual
objects such as windows, pull-down menus,
pointers, and icons.
A CLI (command line interface) is a user
interface to a computer's operating system or
in which the user responds to a visual
prompt by typing in a command on a
specified line, receives a response back from
the system, and then enters another
command, and so forth.
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The File System
The file system of an OS determines
the way files are named and how and
where they are placed on storage
devices, such as hard disks.
Windows, Macintosh, UNIX, and
Linux OSs all employ file systems
that use a hierarchical structure
In a hierarchical file system, files are
placed in logical containers that are
arranged in an upside-down tree
structure.
 UNIX and Linux call these
containers “directory” and
“subdirectory”.
 Windows and Macintosh OSs use
the term "folder" and "subfolder“.
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The File System (Cont …)
The file system of an OS determines more than just how
files and folders are logically organized.
The type of file system used by the computer determines
whether or not files can be secured from other users or
programs.
The file system also defines how data is physically
arranged on the storage media (such as a hard drive).
Some file systems use disk space more efficiently than
others
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OS and File Systems
Different operating systems use different file systems, and
some operating systems can use more than one file system.
For example, although Windows 3.x can use only the
FAT16 file system, Windows 2000/XP can use FAT16,
FAT32, or the New Technology File System (NTFS).
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OS and Their File Systems
OS
Native File Systems
Windows 3.x
FAT16
Windows95, 98, ME
FAT32
WindowsNT, 2000
NTFS
Windows XP
NTFS (or NTFS5)
IBM OS/2
HPFS (High Performance File System)
Linux
ext2/ext3,
Note: Filesystem for CDROM is ISO9660.
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Common Desktop Operating Systems
Microsoft Disk Operating System (MSDOS) is an obsolete OS that is still
used to support legacy business
applications.
Microsoft Windows includes Windows
95, 98, ME, NT, 2000, and XP.
Apple Macintosh OS (Mac OS)
includes OS 8, OS 9, and OS X (OS
10).
Linux includes distributions from
various companies, such as Red Hat,
Caldera, Santa Cruz Operation (SCO),
SuSE, and others.
UNIX includes HP-UX, Sun Solaris,
and others.
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Networking Operating System Overview
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Common Network Operating Systems
The limitations of early desktop OSs led
to the development of more powerful
NOS software
NOSs provide built-in networking
components and network services,
multiuser capability, and sophisticated
file security and file sharing
technologies.
Common NOSs in use today include:
 Microsoft Windows 2000/2003
Server
 Novell NetWare
 Linux
 Unix
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Windows and Linux NOS Comparison
Windows has been marketed as a user-friendly, graphical interface
(GUI), desktop operating system.
The roots of Linux begin with UNIX and with that modular design made
Linux a very popular choice among system administrators to run their
servers.
Text-mode interface functionality
Cost
Obtaining the OS
Ability to run from a CD
Available application software and obtaining application software
Virus vulnerability
Security features
Supporting multiple users
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The Client-Server Model
Most network applications, including Internet-related applications such
as the World Wide Web (WWW) and e-mail, are built around a
client/server relationship.
A server offers network services, such as e-mail to other programs called
clients.
Once enabled, a server program waits to receive requests from client
programs. If a legitimate request is received, the server responds by
sending the appropriate information back to the client.
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The Client-Server Model
Any computer can act as a server as
long as it is connected to the network
and is configured with the appropriate
software.
Most organizations put all of their key
network services on high-end
computers called servers running NOSs
optimized for servicing remote clients.
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Network/NOS Services
Networking operating
systems are designed to
provide network processes to
clients and peers.
Network services include the
World Wide Web (WWW),
file sharing, mail exchange,
directory services, remote
management, and print
services.
Most popular network
processes rely on the TCP/IP
suite of protocols.
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Directory Services
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What is a Directory Service?
A directory service is a software
application that stores and organizes
information about a computer
network's users and network resources,
and that allows network administrators
to manage users' access to the
resources.
A directory service provides system
administrators with centralized control
of all users and resources across the
entire network.
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What is a Directory Service?
Shared resources are published to the directory
Users can locate and access them without ever knowing on which
machine the resources physically reside.
The files, directories, and shares that users access from a single point can
be distributed across multiple servers and locations using distributed
directory and replication services.
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Directory Service Standards
To operate within a NOS, different directory services need to have a
common method of naming and referencing objects.
X.500 defines the Electronic Directory Service (EDS) standards.
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Windows 2000/2003 Active Directory
To use Active Directory, at least one server must be configured as a
Domain Controller (DC).
It is recommended that there be at least two DCs in each domain, for
fault tolerance.
Replication is the process of copying data from one computer to one or
more other computers and synchronizing that data so that it is identical
on all systems.
Active Directory uses multimaster replication to copy directory
information between the domain controllers in a domain.
Each object in Active Directory has an Access Control List (ACL) that
contains all access permissions associated with that object. Permissions
can be either explicitly allowed or denied.
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Domains
A domain is a logical grouping of
networked computers that share a
central directory or database.
Domains have several advantages:
 Centralized administration since all
user information is stored centrally.
 A single logon process that enables
users to access network resources as
well as specify permissions that
control who can and cannot access
these services.
 The ability to expand a network to
extremely large sizes throughout the
world.
Domain
Workgroup
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Network Information Service (NIS) - Linux
Linux uses its own version of Directory
Services called the Network
Information Service (NIS).
The network consists of the NIS server,
slaves, and clients.
The NIS Servers is where the NIS
database is created and maintained.
The NIS slaves act the same way as
NDS servers act in Novell.
The NIS databases are copied to all the
NIS slave servers.
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Characteristics of a Network Operating System
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Overview of NOS Characteristics
Network operating systems (NOSs)
distribute their functions over a number of
networked computers.
It then adds functions that allow access to
shared resources by a number of users
concurrently.
NOS computers take on specialized roles
to accomplish concurrent access to shared
resources.
Client systems contain specialized
software that allows them to request
shared resources that are controlled by
server systems responding to a client
request.
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Differences Between PC and a NOS
The NOS enhances the reach of the client PC by making remote
services available as extensions of the local native operating system.
Although a number of users may have accounts on a PC, only a
single account is active on the system at any given time.
NOS supports multiple user accounts at the same time and enables
concurrent access to shared resources by multiple clients.
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Multiuser, Multitasking, and Multiprocessor Systems
A NOS server is a multitasking system.
Internally, the OS must be capable of
executing multiple tasks or processes at the
same time.
Some systems are equipped with more than
one processor, called multiprocessing
systems.
They are capable of executing multiple
tasks in parallel by assigning each task to a
different processor.
The aggregate amount of work that the
server can perform in a given time is
greatly enhanced in multiprocessor systems.
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NOS Server Hardware
NOS servers are large systems with
additional memory to support multiple
tasks that are all active, or resident, in
memory at the same time.
Additional disk space is also required
on servers to hold shared files and to
function as an extension to the internal
memory on the system.
Because a NOS depends on the
continuous operation of its servers, the
extra hardware components justify the
additional expense.
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Microsoft Windows
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Windows 2000/XP Operating System
XP also offers:
More extensive hardware and driver support.
More user-friendly file-sharing and network configuration
for setting up home networks.
Enhanced wireless network features
Increased security
Remote Desktop control
Overall improvements to the GUI, including the welcome
screen additions, start menu improvements.
Enhanced multimedia support for digital video,
audio, and pictures.
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Windows 2000/XP Operating System
The offline folders feature enables users
to copy and synchronize documents from
the network to the local system so that
they can be accessed when the computer
is not connected to the network.
The Internet Printing Protocol (IPP)
enables users to print to a URL and
manage printers through a web browser
interface.
Built-in disk defragmenters and other
tools and utilities help users maintain and
manage the operating system.
It supports Kerberos security (developing
standard for authenticating network users),
and the features of a Windows 2000
domain as an Active Directory client.
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Linux
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Linux Operating System
Linux is sometimes referred to as "UNIX Lite", and it is designed to run on
Intel-compatible PCs.
However, Linux will run on other machines as well.
Linux brings the advantages of UNIX to home and small business computers.
The following are a few of the most popular types:
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Red Hat Linux
Fedora Core
Linux Mandrake
Caldera eDesktop and eServer
Debian GNU/Linux
Corel Linux
Turbo Linux
Ubuntu
CentOS
SuSe
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Linux Clients / Servers
Windows clients can access Linux
servers without client software if the
UNIX servers run Samba, which is a
program that uses the Server
Message Block (SMB) application
layer protocol.
Windows computers use SMB for
file access across the network.
Samba permits them to see the
Linux file system.
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