1. © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public ITE PC v4.0 Chapter 1 1 Operating Systems CCNA Discovery 1– Chapter 2

2. ITE PC v4.0 Chapter 1 2 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Purpose of an OS  The purpose of an Operating System is to manage the computer system’s data, hardware, software and resources  The OS provides an interface between the user and the computer hardware  The OS acts like a translator between the hardware and user applications

3. ITE PC v4.0 Chapter 1 3 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Parts of an Operating System  All Operating Systems share these 3 components: 1.Kernel 2.Shell 3.File System

4. ITE PC v4.0 Chapter 1 4 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Parts of an OS: The Kernel  The kernel is the part of the OS code that interacts directly with the computer hardware  It is the core of the OS  The kernel consists of a piece of code that is loaded into memory after boot-up  The kernel code tells the computer how to manage hardware, memory, system processes and applications  On Linux and Unix, there is often a file named kernel  Windows systems have many files with name kern or kernel, which are part of the kernel

5. ITE PC v4.0 Chapter 1 5 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Parts of an OS: The Shell  The shell is the part of the OS code that interacts with users and applications  The shell is like a bridge between the user, applications and the kernel, it interprets keyboard strokes, mouse clicks, and other input from the user  The shell also organizes and displays output for the user  There are 2 types of Shells GUI: graphical user interface CLI: command line interface

6. ITE PC v4.0 Chapter 1 6 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public The GUI vs. the CLI  GUI Characteristics: –The user interacts with graphical elements, like windows, menus and icons, using a keyboard, and mouse –makes tasks easier for the user –takes up more disk space –uses more memory and processing power  CLI Characteristics –The user interacts with a text-based screen using text commands –NOS’s rely mostly on the CLI

7. ITE PC v4.0 Chapter 1 7 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Parts of an OS: The file system  The file system determines how and where files are saved on the disk (hard drive) –Windows and Linux both use a hierarchical file system Files are put in logical containers, and stored in an upside-down tree structure The containers in Windows are called folders and subfolders The containers in Linux are called directories and subdirectories  The type of file system used also determines: –Whether files can be secured from other users or programs –How data is physically arranged on a drive –How files are named (ex. Maximum length, illegal characters) –The format for specifying a path, or route, to a file’s destination

8. ITE PC v4.0 Chapter 1 8 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public FAT File Systems  FAT (file allocation table) is one common type of file system used by OS’s  A FAT table is like a map of files on the hard drive  The FAT table references disk clusters –A cluster is the basic unit of measurement for file storage –A file can be stored on many different clusters, but a cluster can only contain data from 1 cluster  There are 3 different types of FAT file systems: FAT FAT 16 FAT 32

9. ITE PC v4.0 Chapter 1 9 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public File System Types FAT : the early DOS systems used the original FAT system Only 8 character filenames are supported, and there is no support for large drives FAT 16 :for use on disk partitions up to 4 GB If you use FAT 16 on larger disks, it just creates larger clusters Windows 3.x used FAT 16 FAT 32 : for use on partitions up to 2 terabytes, it uses smaller cluster sizes FAT 32 was created to minimize the wasted space of FAT 16 Windows 9.x can use FAT 16, or FAT 32 Windows XP can use FAT 32 or NTFS Windows NT, Windows 2000 can use FAT16, FAT32 or NTFS NTFS – new technology File System is a newer, more secure file system, which can be used by Windows 2000, NT, XP, Vista and Server

10. ITE PC v4.0 Chapter 1 10 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Operating System Functions  Operating Systems are designed to have complete control of local hardware resources  They are designed to work with one user at a time.  In order to work with Network Resources an OS needs a redirector –Special software that lets the OS manage network resources –It can be part of the OS or installed as a network client

11. ITE PC v4.0 Chapter 1 11 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public  Originally, OS’s were designed for stand-alone PCs, so they only allowed 1 user to access files and resources  Desktop computers grew in popularity in the 80’s, and companies began to install LANs (local area networks) to connect these desktop PCs, in order to share data and resources  As networks grew in popularity, there became a need to provide file security, user privileges, and shared resources on LANs  Specialized operating systems were created to meet these needs: the Network Operating System (NOS)  With the growth of networking and the Internet, the line has blurred between a strict OS and a true NOS, many modern OS’s have NOS characteristics OS Evolution

12. ITE PC v4.0 Chapter 1 12 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public OS vs. NOS  A NOS is a specialized OS that is designed to: 1.Provide file security 2.Allow multiple user access to resources 3.Provide for user privileges 4.Allows network resources to be treated as local  A NOS is usually run on a server, due to its higher processing and memory requirements –The server provides a centralized point for file storage, shared resources, and security –Users access the server from client machine, which run a regular OS

13. ITE PC v4.0 Chapter 1 13 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Operating System Capabilities Most Modern OS’s share these capabilities  Multitasking – more than one application running at the same time  Multiuser – more than one user sharing applications or hardware at the same time  Multithreading – a program that is broken down into smaller parts and run at the same time Some OS’s also support:  Multiprocessing – more than one processor working at the same time

14. ITE PC v4.0 Chapter 1 14 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public OS Types There are many different OS’s available: –Microsoft Windows: XP, Vista, 2003 Server –UNIX-Based: IBM AIX, Hewlett Packard HPUX, and Sun Solaris –BSD - Free BSD –Linux-Based (Many varieties) –Macintosh OS X –Non-Unix Proprietary: IBM OS/400, z/OS

15. ITE PC v4.0 Chapter 1 15 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public OS Licensing  Most OS’s require the user to purchase and agree to a commercial license, which allows you to install it on only 1 computer –Users are not allowed to modify the code in any way –Structure support is available for a fee –Development is very structured and changes occur slowly  Some OS’s, like Linux and BSD, operate under the GNU Public licensing –GNU OS’s operate using free software –The GPL allows end-users to modify and enhance the code, if they desire, to better suit their environment. –The OS can evolve and change quite quickly

16. ITE PC v4.0 Chapter 1 16 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public OS Requirements  Each OS has specific hardware requirements that are needed to run it –RAM amount –Hard drive support –Processor speed and type –Video Resolution  Most OS’s will specify both a minimum and a recommended hardware requirement list –System performance at the minimum hardware requirement is usually poor and only sufficient to support the OS and no other functionality –The recommended hardware is usually the better option and is more likely to support standard additional applications and resources.

17. ITE PC v4.0 Chapter 1 17 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Choosing an OS  Many factors must be considered when choosing an appropriate OS: –Does it support the user’s requirements –Does it support the applications that will be run –Does the computer have the necessary hardware to run the OS –What resources and support will be needed to support the OS  You should always consider the TCO (total cost of ownership) when purchasing an OS. This includes: –Cost to buy and install it –All costs required to support it

18. ITE PC v4.0 Chapter 1 18 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Disk Partitions  An OS is installed in a defined section of the hard disk, called a disk partition.  Partitioning : involves dividing a disk into sections or logical divisions –Each partition has its own File System –Each partition CAN have its own OS –A disk can have 1 or more partitions

19. ITE PC v4.0 Chapter 1 19 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Disk Partitioning  One of the techniques available to help protect data is to divide the hard drive into multiple partitions: –1 partition for data –1 separate partition for the OS  Typically a network server is configured with multiple partitions before installing a NOS 1.Provides for more security and fault tolerance 2.Data and system files should be kept on separate partitions 3.Creating a separate swap partition will speed up a server’s performance  Enables an OS to be upgraded without the risk of losing data  Simplifies backup and recovery of data files

20. ITE PC v4.0 Chapter 1 20 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Partition Types –Primary partition – the 1st main partition The active partition, or bootable partition that contains a bootable OS Always labeled with a C on a windows system Only the primary partition on a hard drive can be bootable Win 2000 supports more than 1 primary partition per disk There can up to 4 primary partitions in a windows/Linux PARTITION TABLE –This would require 4 separate disks –Extended partition – an additional partition, which uses all of the available disk space not used by the primary partition its really just a placeholder for logical drives There can only be 1 extended partition in a windows/Linux Partition table –Logical Drives: a section created inside an extended partition, which can store data There can be up to 23 logical drives in an extended partition each logical drive gets its own a drive letter Separates information, makes data retrieval faster Can install multiple OS on the same computer

21. ITE PC v4.0 Chapter 1 21 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Partition Table  The partition table is stored in the MBR of a hard disk, and contains partition information  Linux and Windows both use a DOS type partition table –Stored in the MBR, in the boot sector of the hard disk The 1 st sector of a hard disk with an OS on it MBR has a program that finds the 1 st sector of a bootable OS and turns control over to that OS –Contains information about which partitions are bootable  Windows and Linux partition Tables Support –Up to 4 primary partitions In Linux, Numbered 1 to 4 (1 to 3 reserved for Primary) –1 extended partition In Linux, Numbered 4 –23 logical drives In Linux numbered 5 and up  Unix uses a partition table called a VTOC, which supports up to 8 partitions

22. ITE PC v4.0 Chapter 1 22 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Installing an OS  There are various methods for installing an OS.  The method selected for installation is based on : –system hardware –OS being installed –user requirements There are 4 basic options for installing an OS: –Clean Install –Upgrade Install –Multi-boot –Virtualization

23. ITE PC v4.0 Chapter 1 23 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Clean Install  Done a new system or when an upgrade is not possible  deletes all data on the partition where the OS is installed and requires application software to be reinstalled

24. ITE PC v4.0 Chapter 1 24 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Upgrade Install  Can be done when you stay with the same OS platform  system configuration settings, applications and data are preserved  old OS files are replaced with the new OS files

25. ITE PC v4.0 Chapter 1 25 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Multi-Boot  Each OS is contained within its own partition and can have its own files and configuration settings  A start-up menu let the user select the desired OS to boot  Only one OS can run at a time and it has full control of the hardware.

26. ITE PC v4.0 Chapter 1 26 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Virtualization  Enables multiple copies of an OS to be run on a single set of hardware (creates virtual machines)  A technique that is often deployed on servers  Each virtual machine can be treated as a separate computer  Enables a single physical resource to appear to function as multiple logical resources.

27. ITE PC v4.0 Chapter 1 27 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Pre-Installation Checklist A pre-installation checklist helps ensure that the installation process is successful. 1.Verify that all hardware is certified to work with the selected OS. 2.Verify that the hardware resources meet or exceed the published minimum requirements. 3.Confirm that the appropriate installation medium is available – ex. CD or DVD 4.If doing an Upgrade: –Use system diagnostic tools and utilities to ensure the current OS installation is in good condition, free of malicious or damaging files and codes –Complete a full backup of all important files. 5. If performing a clean-install, verify that all application software is available for installation.

28. ITE PC v4.0 Chapter 1 28 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Configuring a Computer for the Network  A network is a group of devices, such as computers, that are connected to each other for the purposes of sharing information and resources.  To physically connect to a network, a computer must have: 1. a network interface card (NIC) 2. a IP network configuration An IP address – a unique address that identifies the computer on a network. Subnet mask- a number used to identify the network on which the computer is connected. Default gateway- the IP address for the device that the computer uses to access the Internet or another network.

29. ITE PC v4.0 Chapter 1 29 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Configuring IP  IP addresses can be assigned in 2 different ways: –Dynamically The computer requests an address from a pool of addresses assigned by another device within the network When the computer is finished with the address it is returned to the pool for assignment to another computer Usually this is done with DHCP services (a DHCP server running DHCP software) –Manually The IP address is entered into the properties of the NIC by the network administrator This is a static address and is permanently assigned to that computer.

30. ITE PC v4.0 Chapter 1 30 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Installation of an Operating System  Prepare your computer to participate in the network DHCP server

31. ITE PC v4.0 Chapter 1 31 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Computer Naming  Some network operating systems and network services use names instead of IP addresses  Each computer on the network should also have a unique name  A computer name provides a user friendly name, making it easier for users to connect to shared resources such as folders and printers  Names must be manually assigned to each device, although some tools do exist to help automate the naming process

32. ITE PC v4.0 Chapter 1 32 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Maintaining the OS  Once an operating system (OS) or application is installed, it is important to keep it up to date with the latest patches.  A patch is a piece of program code that can correct a problem or enhance the functionality of an application program or OS  Patches are provided by the manufacturer to repair a known vulnerability or reported problem.  Computers should be continually updated with the latest patches unless there is a good reason not to do so.

33. ITE PC v4.0 Chapter 1 33 © 2007 Cisco Systems, Inc. All rights reserved.Cisco Public Windows Updates  Updates to Windows can be configured in several different ways: –Automatic Install Updates are automatically downloaded and installed –Prompt for Permission Updates are automatically downloaded, but the user must choose whether or not to install them –Manual Major patches, like Service Packs should be manually downloaded and installed