Foundation ITO

49 File Management The above figure shows the general hierarchy of the storage in an operating system. In this figure, the root directory is present at the highest level in the hierarchical structure. It includes all the subdirectories in which the files are stored. The subdirectory is a directory present inside another directory in the file storage system. The directory-based storage system ensures better organization of files in the memory of the computer system. The file management of function in the operating system (OS) is based on the following concepts: ➢ File Attributes-It specifies the characteristics of the files such as type, date of last modification, size, location on disk, etc. file attributes help the user to understand the value and location of files. File attributes are one most important feature. It is used to describe all the information regarding a particular file. ➢ File Operations-It specifies the task that can be performed on a file such as opening and closing of a file. ➢ File Access Permission-It specifies the access permissions related to a file such as read and write. ➢ File Systems-It specifies the logical method of file storage in a computer system. Some of the commonly used file’s systems include FAT and NTFS.

50 2.4 Summary • Computer hardware includes the physical parts of a computer, such as the case, central processing unit (CPU), monitor, mouse, keyboard, computer data processing unit. • Computer hardware is the physical components that a computer system requires to function. • Computer operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. 2.5 Glossary • Boot: To start up a computer. Cold boot means restarting the computer after the power is turned off. Warm boot means restarting the computer without turning off the power. • Cache: A small data-memory storage area that a computer can use to instantly re-access data instead of re-reading the data from the original source, such as a hard drive • Chip: A tiny wafer of silicon-containing miniature electric circuits that can store millions of bits of information. • Cursor: A moving position indicator displayed on a computer monitor that shows a computer operator where the next action or operation will take place. 2.6 References • https://www.crucial.com/articles/pc-builders/what-is-computer-hardware • https://web.stanford.edu/class/cs101/hardware-1.html • https://www.techtarget.com/searchnetworking/definition/hardware • https://www.guru99.com/operating-system-tutorial.html • https://www.britannica.com/technology/operating-system

51 UNIT - 3: UNIX BASICS Structure 3.0 Learning Objectives 3.1 Introduction 3.2 History of UNIX 3.3 Unix commands 3.4 Exercises 3.5 Summary 3.6 Glossary 3.7 Reference 3.0 Learning Objectives After studying this unit, you will be able to: • Identify UNIX commands • Elaborate History of Unix • Differentiate between different Versions • Exercise on basic Unix commands 3.1 Introduction UNIX is an operating system that was first developed in the 1960s and has been under constant development ever since. By operating system, we mean the suite of programs that make the computer work. It is a stable, multi-user, multi-tasking system for servers, desktops and laptops. UNIX systems also have a graphical user interface (GUI) similar to Microsoft Windows which provides an easy-to-use environment. However, knowledge of UNIX is required for operations that aren’t covered by a graphical program, or for when there are no windows in interfaces available, for example, in a telnet session. Types of UNIX

52 The Linux PenguinThere are many different versions of UNIX, although they share common similarities. The most popular varieties of UNIX are Sun Solaris, GNU/Linux, and MacOS X. The UNIX operating system The UNIX operating system is made up of three parts; the kernel, the shell and the programs. The kernel The kernel of UNIX is the hub of the operating system: it allocates time and memory to programs and handles the filestore and communications in response to system calls. As an illustration of the way that the shell and the kernel work together, suppose a user types rm myfile (which has the effect of removing the file myfile). The shell searches the filestore for the file containing the program rm, and then requests the kernel, through system calls, to execute the program rm on myfile. When the process rm myfile has finished running, the shell then returns the UNIX prompt % to the user, indicating that it is waiting for further commands. The shell The shell acts as an interface between the user and the kernel. When a user logs in, the login program checks the username and password, and then starts another program called the shell. The shell is a command line interpreter (CLI). It interprets the commands the user types in and arranges for them to be carried out. The commands are themselves programs: when they terminate, the shell gives the user another prompt (% on our systems). The adept user can customise his/her own shell, and users can use different shells on the same machine.

53 UNIX Architecture 3.2 History of Unix At the end of the 1960s, the young engineer at AT&T Bell Labs, Kenneth Thompson, worked on the Multiplexing Information and Computer Services (Multics) operating system. Multics was an experimental operating system for GE-645 mainframe, developed in the 1960s by the Massachusetts Institute of Technology, Bell Labs, and General Electric. Although Multics introduced many innovations, it had many problems. At the end of the 1960s, Bell Labs, frustrated by the slow progress and difficulties, pulled out of the project. Thus, with the help of his colleagues Dennis Ritchie, Douglas McIlroy, and Joe Ossanna, Thompson decided to experiment with some Multics concepts and redo it on a much smaller scale. Thus in 1969, the idea of the now-ubiquitous Unix was born. While Ken Thompson still had access to the Multics environment, he wrote simulations for the new file and paging system on it. Later the group continued his work on blackboards and scribbled notes. In 1969, Thompson developed a beautiful game, Space Travel, first written on Multics, then transliterated into Fortran for GECOS, and finally for a little-used PDP-7 at Bell Labs. He later decided to use the same PDP-7 for the implementation of the first UNIX. On this PDP- 7 and using its assembly language, the team of researchers, initially without financial support from Bell Labs, led by Thompson and Ritchie, developed a hierarchical file system, the concepts of computer processes and device files, a command-line interpreter, and some small utility programs. The name UNICS was coined in 1970 by the team member Brian Kernighan, who played on Multics name. UNICS, Uniplexed

54 Information, and Computing System could eventually support multiple simultaneous users and was later shortened to UNIX. In 1970 Thompson and Ritchie wanted to use Unix on a much larger machine than the PDP-7 and traded the promise of adding text processing capabilities to Unix to some financial support from Bell, porting the code for a PDP-11/20 machine. Thus, for the first time in 1970, the Unix operating system was officially named and ran on the PDP-11/20. It added a text formatting program called roff and a text editor. All three were written in PDP-11/20 assembly language. Bell Labs used this initial “text processing system,” made up of Unix, roff, and the editor, for text processing of patent applications. Roff soon evolved into troff, the first electronic publishing program with a full typesetting capability. In 1972, Unix was rewritten in the C programming language, contrary to the general notion at the time “that something as complex as an operating system, which must deal with time-critical events, had to be written exclusively in assembly language. “The migration from assembly language to the higher-level language C resulted in much more portable software, requiring only a relatively small amount of machine-dependent code to be replaced when porting Unix to other computing platforms’ made Unix available to universities and commercial firms, and the United States government under license. The license included all source code, including the machine-dependent parts of the kernel, which were written in the PDP-11 assembly code. Copies of the annotated Unix kernel sources circulated widely in the late 1970s as a much-copied book, which led to considerable use of Unix as an educational example. At some point, ARPA, Advanced Research Projects Agency, adopted Unix as a standard language for the Arpanet community. During the late 1970s and early 1980s, the influence of Unix in academic circles led to the large-scale adoption of Unix by many commercial start- ups. For example, Solaris, HP-UX, and AIX. Today, besides certified Unix systems such as those already mentioned, Unix-like operating systems such as Linux and BSD descendants (FreeBSD, NetBSD, and OpenBSD) are commonly encountered. Unix versions There are many different versions of UNIX. Until a few years ago, there were two main versions: the line of UNIX releases that started at AT&T (the latest is System V Release 4), and another line from the University of California at Berkeley (the latest version is BSD 4.4). Some other major commercial versions include SunOS, Solaris, SCO UNIX, AIX, HP/UX, and ULTRIX. The freely available versions include Linux and FreeBSD (FreeBSD is based on 4.4BSD-Lite). Many versions of UNIX, including System V Release 4, merge earlier AT&T releases with BSD features. The recent POSIX standard for UNIX-like operating systems defines a single interface to UNIX. Although advanced features differ among systems, you should be able to use this introductory handbook on any type of system. UNIX can be used the way it was originally designed, on typewriter-like terminals. Most versions of UNIX can also work

55 with window systems, which allow each user to have more than one “terminal” on a single display. 3.3 Basic UNIX Commands Sometimes, commands are also referred as “programs” since whenever you run a command, it’s the corresponding program code, written for the command, which is being executed. Unix Shell Commands ▪ clear – clear screen ▪ history – show history of previous commands Unix user’s commands These commands allow you to get basic information about Unix users in your environment. ▪ whoami – show your username ▪ id – print user identity ▪ groups – show which groups user belongs to ▪ passwd – change user password ▪ who – find out who is logged into the system ▪ last – show history of logins into the system Text file operations in Unix Most of the important configuration in Unix is in clear text files, these commands will let you quickly inspect files or view logs:

56 • cat – concatenate files and show contents to the standard output • more – basic pagination when viewing text files or parsing Unix commands output • less – an improved pagination tool for viewing text files (better than more commands) • head – show the first 10 lines of a text file (you can specify any number of lines) • tail – show the last 10 lines of a text file (any number can be specified) • grep – search for patterns in text files Unix directory management commands Navigating filesystems and managing directories: ▪ cd – change directory ▪ pwd – confirm current directory ▪ ln – make links and symlinks to files and directories ▪ mkdir – make a new directory ▪ rmdir – remove directories in Unix Unix system status commands Most useful commands for reviewing hostname configuration and vital stats: ▪ hostname – show or set server hostname ▪ w – display system load, who’s logged in and what they are doing ▪ uname – print Unix system information Reboot ▪ shutdown – graceful shutdown and reboot of your system ▪ halt – ungraceful (without stopping OS services) shutdown ▪ reboot – ungraceful reboot (without stopping OS services) Networking commands in Unix Most useful commands for inspecting network setup and exploring network connections and ports: ▪ ifconfig – show and set IP addresses (found almost everywhere) ▪ ip – show and set IP addresses (in recent Linux versions) ▪ ping – check if remote host is reachable via ICMP ping ▪ netstat – show network stats and routing information Process management Listing processes and confirming their status, and stopping processes if needed: ▪ ps – list processes

57 ▪ top – show tasks and system status ▪ kill – kill a process (stop the application running) Remote access commands ssh is really the only way to go, but it’s important to know telnet as well: ▪ telnet – clear-text (insecure) remote access protocol ▪ ssh – Secure Shell – encrypted remote access client File transfers commands Always useful to know how to copy files between servers or just download some package from the web:

58 3.4 Exercises On UNIX Commands 1. Copy all files in the current directory whose names contain the character strings \"notes\" or \"misc\" into the subdirectory \"Misc\". What commands did you use? cp *notes* Misc cp *misc* Misc or cp *notes* *misc* Misc 2. Copy all files in the current directory whose names contain the character string \"let\" into the subdirectory \"Letters\". What command did you use? cp *let* Letters cp *notes* Misc cp *misc* Misc or cp *notes* *misc* Misc 3. Delete all files which contain the sequence \"del\". What command did you use? rm -i *del* 4. List the files in the directory \"/bin\" that end in \"sh\". What command did you use? ls /bin/*sh 5. What command lists the files in the current directory that begin with upper case letters? ls -d [A-Z]* 3.5 Summary • UNIX is a computer operating system. • UNIX is a multi-user, multi-tasking operating system • UNIX was created in Bell Labs research center. • UNIX system is functionally organized at three levels: The kernel, which schedules tasks and manages storage; • UNIX systems also have a graphical user interface (GUI) similar to Microsoft Windows which provides an easy-to-use environment. 3.6 Glossary • .(dot): A shorthand expression representing the user's working directory.

59 • Application: A program or set of programs designed to perform a particular useful function or set of functions; for example, the Source Code Control System (SCCS) is an application for managing program source code. • binary file: A file created by a compilation process. Binary files contain codes that are not part of the ASCII character set and utilize all 256 possible byte values. • Call: In a programming language, a statement that invokes a subroutine, function, or procedure. 3.7 References • https://www.unixtutorial.org/basic-unix-commands • https://www.guru99.com/must-know-linux-commands.html • https://unix.org/ • https://www.techtarget.com/searchdatacenter/definition/Unix

60 UNIT - 4: SERVER OS & DESKTOP OS OVERVIEW Structure 4.0 Learning Objectives 4.1 Introduction 4.2 Basics of Windows Physical Server 4.3 Basic of Windows Virtual Server 4.4 Types of OS &editions 4.5 Difference between Windows Server OS & Windows Desktop OS 4.6 Summary 4.7 Glossary 4.8 References 4.0 Learning Objectives After studying this unit, you will be able to • Identify Windows Physical Server • Identify Windows Virtual Server • Distinguish between Windows Server OS & Windows Desktop OS • List the Types & Editions of OS 4.1 Introduction A server operating system (OS) is a type of operating system that is designed to be installed and used on a server computer. It is an advanced version of an operating system, having features and capabilities required within a client-server architecture or similar enterprise computing environment. Some common examples of server OSs include: • Red Hat Enterprise Linux • Windows Server • Mac OS X Server

61 Some of the key features of a server operating system include: ➢ Ability to access the server both in GUI and command-level interface ➢ Execute all or most processes from OS commands ➢ Advanced-level hardware, software and network configuration services ➢ Install/deploy business applications and/or web applications ➢ Provides central interface to manage users, implement security and other administrative processes ➢ Manages and monitors client computers and/or operating systems The desktop OS is the environment where the user controls a personal computer (Desktop, Notebook PC). It aids in the management of computer hardware and software resources. It supports fundamental features such as task scheduling, peripheral control, printing, input/output, and memory allocation. Five of the most common operating systems are Microsoft Windows, Apple macOS, Linux, Android, and Apple's iOS. 4.2 Basics of Windows Physical Server Essentially, Windows Server is a line of operating systems that Microsoft specifically creates for use on a server. Servers are extremely powerful machines that are designed to run constantly and provide resources for other computers. Physical servers are powerful computers usually stored in a data center for business-use cases that run operating systems and applications off their internal hardware resources. This enables them to run applications and programs that draw directly on the power of that physical server's hardware Windows Server is a group of operating systems designed by Microsoft that supports enterprise-level management, data storage, applications, and communications. Windows Server

62 Today's servers are primarily available in three forms: racks, blades and mainframes. The majority of IT teams turn to rack and blade servers to meet their server requirements. Some teams opt for mainframe computers to handle their workloads, although not nearly to the extent of rack and blade servers. Physical Server 4.3 Basics of Virtual Server Microsoft Virtual Server is a scalable server virtualization program distributed by Microsoft that enables multiple operating systems (OSs) to run on a single physical server. The program operates without third-party device drivers and provides isolation between partitions. • A virtual machine environment for Windows servers from Microsoft that supports most x86 operating systems as guests. • It is used to run multiple copies of Windows as well as Linux in a virtualized server environment. • Virtual Server was superseded by Hyper-V.

63 Virtual Server 4.4 Types of OS & Editions Some widely used operating systems are as follows- 1. Batch Operating System – This type of operating system does not interact with the computer directly. There is an operator which takes similar jobs having the same requirement and group them into batches. It is the responsibility of the operator to sort jobs with similar needs. Batch Operating System

64 Advantages of Batch Operating System: It is very difficult to guess or know the time required for any job to complete. Processors of the batch systems know how long the job would be when it is in queue • Multiple users can share the batch systems • The idle time for the batch system is very less • It is easy to manage large work repeatedly in batch systems Disadvantages of Batch Operating System: • The computer operators should be well known with batch systems • Batch systems are hard to debug • It is sometimes costly • The other jobs will have to wait for an unknown time if any job fails Examples of Batch based Operating System: Payroll System, Bank Statements, etc. 2. Time-Sharing Operating Systems – Each task is given some time to execute so that all the tasks work smoothly. Each user gets the time of CPU as they use a single system. These systems are also known as Multitasking Systems. The task can be from a single user or different users also. The time that each task gets to execute is called quantum. After this time interval is over OS switches over to the next task. Time Sharing Operating System Advantages of Time-Sharing OS:

65 • Each task gets an equal opportunity • Fewer chances of duplication of software • CPU idle time can be reduced Disadvantages of Time-Sharing OS: • Reliability problem • One must have to take care of the security and integrity of user programs and data • Data communication problem 3. Distributed Operating System – These types of the operating system are a recent advancement in the world of computer technology and are being widely accepted all over the world and, that too, with a great pace. Various autonomous interconnected computers communicate with each other using a shared communication network. Independent systems possess their own memory unit and CPU. These are referred to as loosely coupled systems or distributed systems. These system’s processors differ in size and function. The major benefit of working with these types of the operating system is that it is always possible that one user can access the files or software which are not actually present on his system but some other system connected within this network i.e., remote access is enabled within the devices connected in that network. Structure of Operating System

66 Advantages of Distributed Operating System: • Failure of one will not affect the other network communication, as all systems are independent from each other • Electronic mail increases the data exchange speed • Since resources are being shared, computation is highly fast and durable • Load on host computer reduces • These systems are easily scalable as many systems can be easily added to the network • Delay in data processing reduces Disadvantages of Distributed Operating System: • Failure of the main network will stop the entire communication • To establish distributed systems, the language which is used are not well defined yet • These types of systems are not readily available as they are very expensive. Examples of Distributed Operating systems are- LOCUS, etc. 4. Network Operating System – These systems run on a server and provide the capability to manage data, users, groups, security, applications, and other networking functions. These types of operating systems allow shared access of files, printers, security, applications, and other networking functions over a small private network. One more important aspect of Network Operating Systems is that all the users are well aware of the underlying configuration, of all other users within the network, their individual connections, etc. and that’s why these computers are popularly known as tightly coupled systems.

67 Network Operating System Advantages of Network Operating System: • Highly stable centralized servers • Security concerns are handled through servers • New technologies and hardware up-gradation are easily integrated into the system • Server access is possible remotely from different locations and types of systems Disadvantages of Network Operating System: • Servers are costly • User has to depend on a central location for most operations • Maintenance and updates are required regularly Examples of Network Operating System are Microsoft Windows Server 2003, Microsoft Windows Server 2008, UNIX, Linux, Mac OS X, Novell NetWare, BSD, etc. 5. Real-Time Operating System – These types of OSs serve real-time systems. The time interval required to process and respond to inputs is very small. This time interval is called response time. Real-time systems are used when there are time requirements that are very strict like missile systems, air traffic control systems, robots, etc. 5. Real-Time Operating System – These types of OSs serve real-time systems. The time interval required to process and respond to inputs is very small. This time interval is called response time. Real-time systems are used when there are time

68 requirements that are very strict like missile systems, air traffic control systems, robots, etc. RTOS Structure Advantages of RTOS: • Maximum Consumption: Maximum utilization of devices and system, thus more output from all the resources • Task Shifting: The time assigned for shifting tasks in these systems are very less. For example, in older systems, it takes about 10 microseconds in shifting one task to another, and in the latest systems, it takes 3 microseconds. • Focus on Application: Focus on running applications and less importance to applications that are in the queue. • Real-time operating system in the embedded system: Since the size of programs is small, RTOS can also be used in embedded systems like in transport and others. • Error Free: These types of systems are error-free. • Memory Allocation: Memory allocation is best managed in these types of systems. Disadvantages of RTOS: • Limited Tasks: Very few tasks run at the same time and their concentration is very less on few applications to avoid errors.

69 • Use heavy system resources: Sometimes the system resources are not so good and they are expensive as well. • Complex Algorithms: The algorithms are very complex and difficult for the designer to write on. • Device driver and interrupt signals: It needs specific device drivers and interrupts signals to respond earliest to interrupts. • Thread Priority: It is not good to set thread priority as these systems are very less prone to switching tasks. Examples of Real-Time Operating Systems are Scientific experiments, medical imaging systems, industrial control systems, weapon systems, robots, air traffic control systems, etc. Editions of OS • The OS translates the instructions for the CPU, so the applications instructions have to be understood by the OS before they can be translated. • Developer’s document all of their changes for this purpose, and the changes are associated with a version or edition number. • An example of Editions of Windows has been shown in the image below. 4.5 Difference Between Windows Server OS & Windows Desktop OS S.No. Categories Windows Windows Server 1 RAM Up to 2 TB (can go up Up to 24 TB to 6 TB with Windows 10 Pro for Workstation

70 Maximum 4 CPUs in 2 Number of CPUs case of Windows 10 – Pro for Workstation Edge, Cortana, 3 Features Included Microsoft Store, Timeline and more 4 Network Connections Up to 20 More than 20 (depends upon the hardware capability Free (if upgrading 5 Price from Windows 7, 8, or $500 to $6200 8.1) 6 Tasks Foreground Background 4.5 Summary • Server operating system (OS) is a type of operating system that is designed to be installed and used on a server computer. • Server of Microsoft Virtual Server is a scalable server virtualization program distributed by Microsoft that enables multiple operating systems (OSs) to run on a single physical server. 4.7 Glossary • Client: A single user of a network application that is operated from a server. • Director: A repository where all files are kept on a computer. • File: A set of data that is stored in the computer. • Input: Data that goes into a computer device.

71 4.8 References • https://www.geeksforgeeks.org/difference-between-server-os-and-client-os/ • https://www.guru99.com/operating-system-tutorial.html • https://techvidvan.com/tutorials/types-of-operating-system/ • https://computer.howstuffworks.com/operating-system3.htm

72 UNIT - 5: NETWORK BASICS Structure 5.0 Learning Objectives 5.1 Introduction 5.2 Basics of networking 5.3 Various Network Devices at TCP/IP & OSI Layer 5.4 IP Addressing & Subnetting 5.5 Network Topologies & Administration 5.6 Summary 5.7 Glossary 5.8 References 5.0 Learning Objectives After studying this unit, you will be able to • Apply Networking - Concepts • Recall Networking Features • Identify TCP/IP & OSI Layers • Recognise IP Addressing & Subnetting, Network Topologies & Administration 5.1 Introduction A computer network is a system that connects numerous independent computers in order to share information (data) and resources. The integration of computers and other different devices allows users to communicate more easily. A computer network is a collection of two or more computer systems that are linked together. A network connection can be established using either cable or wireless media. Hardware and software are used to connect computers and tools in any network. A computer network consists of various kinds of nodes. Servers, networking hardware, personal computers, and other specialized or general-purpose hosts can all be nodes in a computer network. Hostnames and network addresses are used to identify them.

73 Aim of Networking: • Programs do not have to execute on a single system because of resource and load sharing. • Reduced costs – Multiple machines can share printers, tape drives, and other peripherals. • Reliability – If one machine fails, another can take its place. • Scalability (it’s simple to add more processors or computers) • Communication and mail (people living apart can work together) • Information Access (remote information access, access to the internet, e-mail, video conferencing, and online shopping) • Entertainment that is interactive (online games, videos, etc.) • Social Networking 5.2 Networking Concepts A network consists of two or more computers that are linked in order to share resources (such as printers and CDs), exchange files, or allow electronic communications. Reliability Computer network can use the alternative source for the data communication in case of any hardware failure. Features of Networking A list of Computer network features is given below. ▪ Communication speed ▪ File sharing ▪ Back up and Roll back is easy ▪ Software and Hardware sharing ▪ Security ▪ Scalability ▪ Reliability

74 Features of Computer Network • Communication speed: Network provides us to communicate over the network in a fast and efficient manner. For example, we can do video conferencing, email messaging, etc. over the internet. Therefore, the computer network is a great way to share our knowledge and ideas. • File sharing: File sharing is one of the major advantages of the computer network. Computer network provides us to share the files with each other. • Back up and Roll back is easy: Since the files are stored in the main server which is centrally located. Therefore, it is easy to take the back up from the main server. • Software and Hardware sharing: We can install the applications on the main server; therefore, the user can access the applications centrally. So, we do not need to install the software on every machine. Similarly, hardware can also be shared. • Security: Network allows the security by ensuring that the user has the right to access certain files and applications.

75 • Scalability: Scalability means that we can add the new components on the network. Network must be scalable so that we can extend the network by adding new devices. But it decreases the speed of the connection and data of the transmission speed also decreases, this increases the chances of error occurring. This problem can be overcome by using the routing or switching devices. • Reliability: Computer network can use the alternative source for the data communication in case of any hardware failure. Types of Networks 1. Division based on the communication medium • Wired Network: As we all know, “wired” refers to any physical medium made up of cables. Copper wire, twisted pair, or fiber optic cables are all options. A wired network employs wires to link devices to the Internet or another network, such as laptops or desktop PCs. • Wireless Network: “Wireless” means without wire, media that is made up of electromagnetic waves (EM Waves) or infrared waves. Antennas or sensors will be present on all wireless devices. Cellular phones, wireless sensors, TV remotes, satellite disc receivers, and laptops with WLAN cards are all examples of wireless devices. For data or voice communication, a wireless network uses radiofrequency waves rather than wires. 4. Based on types of communication: Point to Point networks: Point-to-Point networking is a type of data networking that establishes a direct link between two networking nodes.A direct link between two devices, such as a computer and a printer, is known as a point-to-point connection. Broadcast networks: In broadcast networks, a signal method in which numerous parties can hear a single sender. Radio stations are an excellent illustration of the “Broadcast Network” in everyday life. The radio station is a sender of data/signal in this scenario, and data is only intended to travel in one direction. Away from the radio transmission tower, to be precise. 4. Based on type of architecture: P2P Networks: Computers with similar capabilities and configurations are referred to as peers. “Peer to Peer” is the abbreviation for “peer to peer.” The “peers” in a peer-to-peer network are computer systems that are connected to each other over the Internet. Without the use of a central server, files can be shared directly between systems on the network. • Client – Server Networks: Each computer or process on the network is either a client or a server in a client-server architecture (client/server). The client asks services from the server, which the server provides. Servers are high-

76 performance computers or processes that manage disc drives (file servers), printers (print servers), or network traffic (network servers) • Hybrid Networks: The hybrid model refers to a network that uses a combination of client-server and peer-to-peer architecture. E.g.: Torrent. A computer network is mainly of four types: • LAN (Local Area Network) • PAN (Personal Area Network) • MAN (Metropolitan Area Network) • WAN (Wide Area Network) Types of Computer Network LAN (Local Area Network) • Local Area Network is a group of computers connected to each other in a small area such as building, office. • LAN is used for connecting two or more personal computers through a communication medium such as twisted pair, coaxial cable, etc. • It is less costly as it is built with inexpensive hardware such as hubs, network adapters, and ethernet cables. • The data is transferred at an extremely faster rate in Local Area Network. • Local Area Network provides higher security. PAN (Personal Area Network) Personal Area Network is a network arranged within an individual person, typically within a range of 10 meters. Personal Area Network is used for connecting the computer devices of personal use is known as Personal Area Network. • Personal Area Network covers an area of 30 feet.

77 • Personal computer devices that are used to develop the personal area network are the laptop, mobile phones, media players, and play stations. PAN There are two types of Personal Area Network: Types of PAN • Wired Personal Area Network • Wireless Personal Area Network Wireless Personal Area Network: Wireless Personal Area Network is developed by simply using wireless technologies such as WiFi, Bluetooth. It is a low range network.

78 Wired Personal Area Network: Wired Personal Area Network is created by using the USB. Examples of Personal Area Network: • Body Area Network: Body Area Network is a network that moves with a person. For example, a mobile network moves with a person. Suppose a person establishes a network connection and then creates a connection with another device to share the information. • Offline Network: An offline network can be created inside the home, so it is also known as a home network. A home network is designed to integrate the devices such as printers, computer, television but they are not connected to the internet. • Small Home Office: It is used to connect a variety of devices to the internet and to a corporate network using a VPN MAN (Metropolitan Area Network) • A metropolitan area network is a network that covers a larger geographic area by interconnecting a different LAN to form a larger network. • Government agencies use MAN to connect to the citizens and private industries. • In MAN, various LANs are connected to each other through a telephone exchange line. • The most widely used protocols in MAN are RS-232, Frame Relay, ATM, ISDN, OC-3, ADSL, etc. • It has a higher range than Local Area Network (LAN). MAN

79 Uses of Metropolitan Area Network: • MAN is used in communication between the banks in a city. • It can be used in an Airline Reservation. • It can be used in a college within a city. • It can also be used for communication in the military. WAN (Wide Area Network) A Wide Area Network is a network that extends over a large geographical area such as states or countries. • A Wide Area Network is quite bigger network than the LAN. • A Wide Area Network is not limited to a single location, but it spans over a large geographical area through a telephone line, fibre optic cable or satellite links. • The internet is one of the biggest WAN in the world. • A Wide Area Network is widely used in the field of Business, government, and education. WAN

80 Examples of Wide Area Network: • Mobile Broadband: A 4G network is widely used across a region or country. • Last mile: A telecom company is used to provide the internet services to the customers in hundreds of cities by connecting their home with fiber. • Private network: A bank provides a private network that connects the 44 offices. This network is made by using the telephone leased line provided by the telecom company. 5.3 Various Network Devices at Tcp/Ip & OSI Layer TCP/IP stands for Transmission Control Protocol/Internet Protocol and is a suite of communication protocols used to interconnect network devices on the internet The TCP/IP Protocol Stack is made up of four primary layers: The Application, Transport, Network, and Link layers. Physical layer of TCP/IP model is responsible for physical connectivity of two devices. Some of the devices used in Physical layers are as follows: • Hubs: Hubs are devices commonly used to connect segments of a LAN. It contains multiple input/output ports. when signal is at any input port, this signal will be made at all output ports except the one it is coming from. • Cables: In Wired network architecture (e.g Ethernet), cables are used to interconnect the devices. some of the types of cables are coaxial cable, optical fiber cable, and twisted pair cable. • Modem: A modem converts digital signals generated by the computer into analog signals which, then can be transmitted over a cable line and transforms incoming analog signals into digital equivalents. • Repeaters: Repeaters are used in transmission systems to regenerate analog or digital signals distorted by transmission loss. Analog repeaters can only amplify the signal whereas digital repeaters can reproduce a signal to near its original quality. The Data Link layer is responsible to transfer data from one device to another devicebased on the MAC address. Some of the devices used in the Data Link layer are, some of the devices used in Physical layers are as follows:

81 • Bridges: A bridge is a type of computer network device that provides interconnection with other networks that use the same protocol, connecting two different networks together and providing communication between them. • Switch: A network switch is a multiport network bridge that uses MAC addresses to forward data at the data link layer (layer 2) of the OSI model. Some switches can also forward data at the network layer (layer 3) by additionally incorporating routing functionality. Such switches are commonly known as layer-3 switches or multilayer switches. Network Interface Card: Network interface card is an electronic device that is mounted on ROM of the com that connects a computer to a computer network, usually a LAN. It is considered a piece of computer hardware. Most modern computers support an internal network interface controller embedded in the motherboard directly rather than provided as an external component. Network Layer layer is responsible for creating routing table, and based on routing table, forwarding of the input request. Some of the Devices used in Network Layer are: • Routers: A router is a switch like device that routes/forwards data packets based on their IP addresses. Routers normally connect Local Area Network (LANs) and Wide Are Network (WANs) together and have a dynamically updating routing table based on which they make decisions on routing the incoming packets. • Brouters: A bridge router or brouter is a network device that works as a bridge and as a router. The brouter routes packets for known protocols and simply forwards all other packets as a bridge would. Brouters operate at both the network layer for routable protocols (or between network with different data link layer protocol ex. one is running on ethernet (802.3) and other network is running on Token ring (802.5)) and at the data link layer for non-routable protocols (or both network is using same data link layer protocol).

82 Routers 4. Transport Layer is responsible for end-to-end communication. Some of the transport layer devices are: • Gateways: In computer networking, a gateway is a component that is part of two networks, which use different protocols. The gateway is a protocol converter which will translate one protocol into the other. A router is a special case of a gateway. • Firewall: A firewall is a system designed to prevent unauthorized access to or from a private network, some of the functionalities of firewall are, packet filtering and as a proxy server. Application Layer is the top most layer of TCP/IP Model that provides the interface between the applications and network. The application layer is used to exchange messages. Some of the devices used in Application layer are,

83 • PC’s (Personal Computer), Phones, Servers • Gateways and Firewalls 5.4 IP Addressing & Subnetting IP addressing IP address stands for internet protocol address; it is an identifying number that is associated with a specific computer or computer network. When connected to the internet, the IP address allows the computers to send and receive information. An IP address allows computers to send and receive data over the internet. Most IP addresses are purely numerical, but as internet usage grows, letters have been added to some addresses. There are generally four types of IP addresses: public, private, static, and dynamic. While the public and private are indicative of the location of the network i.e., private being used inside a network while the public is used outside of a network on the other hand static and dynamic indicate permanency. A static IP address is one that was manually created, as opposed to having been assigned. A static address also does not change, whereas a dynamic IP address has been assigned by a Dynamic Host Configuration Protocol (DHCP) server and is subject to change. Dynamic IP addresses are the most common type of internet protocol addresses. Dynamic IP addresses are only active for a certain amount of time; after which they expire. The computer will either automatically request a new lease, or the computer may receive a new IP address. An IP address can be compared to a Social Security Number (SSN) since each one is completely unique to the computer or user it is assigned to. The creation of these numbers allows routers to identify where they are sending information on the internet. They also make sure that the correct devices are receiving what is being sent. Much like the post office needs a mailing address to deliver a package, a router needs an IP address to deliver to the web address requested. IP address

84 Subnetting Each IP class is equipped with its own default subnet mask which bounds that IP class to have a prefixed number of Networks and prefixed number of Hosts per network. Classful IP addressing does not provide any flexibility of having smaller number of Hosts per Network or more Networks per IP Class. Benefits of Subnetting • Subnetting divides broadcast domains, meaning that traffic is routed efficiently, improving speed and network performance. • A subnet mask ensures that traffic remains within its designated subnet. This reduces major congestion and reduces the load imparted on the network. With sub- networks, less distance needs to be traveled by data packets, enhancing network performance. • With different subnets within your larger network, you can be more aware of route maps. These will help you to identify potential threats. With subnets, devices will not be able to access the whole network, meaning that companies can dictate which hardware and users have access to more sensitive data. Network security can be boosted. • Sound organization is crucial within large businesses. This extends to your network and routers. With subnetting, companies have full control over their traffic and data packets. 5.5 Network Topologies & Administration Network topology refers to how various nodes, devices, and connections on your network are physically or logically arranged in relation to each other. The layout of your network is important for several reasons. Above all, it plays an essential role in how and how well your network functions. Choosing the right topology for your company’s operational model can increase performance while making it easier to locate faults, troubleshoot errors, and more effectively allocate resources across the network to ensure optimal network health. A streamlined and properly managed network topology can increase energy and data efficiency, which can in turn help to reduce operational and maintenance costs.

85 Network Topologies There are several different logical and physical network topologies from which administrators can choose to build a secure, robust, and easily maintainable topology. The most popular configurations include: • Bus network topology -Also known as backbone network topology, this configuration connects all devices to a main cable via drop lines. The advantages of bus network topology lie in its simplicity, as there is less cable required than in alternative topologies, which makes for easy installation. • Mesh network topology -A dedicated point-to-point link connects each device on the network to another device on the network, only carrying data between two devices. • Ring network topology -Two dedicated point-to-point links connect a device to the two devices located on either side of it, creating a ring of devices through which data is forwarded via repeaters until it reaches the target device. • Star network topology - The most common network topology, star topology connects each device in the network to a central hub. Devices can only communicate with each other indirectly through the central hub. • Hybrid network topology - Any combination of two or more topologies is a hybrid topology. • Tree network topology -This topology consists of a parent-child hierarchy in which star networks are interconnected via bus networks. Nodes branch out linearly from one root node, and two connected nodes only share one mutual connection.

86 • Multi-access network topology, also known as a non-broadcast multiple access network (NBMA), consists of multiple linked hosts in which data is transferred directly from one computer to another single host across a switched fabric or over a virtual circuit. 5.6 Summary • Computer network is a group of two or more interconnected computer systems • Computer networks help you to connect with multiple computers together to send and receive information. • Computer network has Switches, it works as a controller which connects computers, printers, and other hardware devices • Comuter network has different topologies like bus, ring, star, mesh etc. 5.7 Glossary • LAN: It stands for Local Area Network and covers a small area such as a small office or home. It physically connects all the computers located in the premises. • WAN: It stands for Wide Area Network and covers a wide area such as a city. • IP address: An IP address is a unique set of numbers or combination of letters and numbers that are assigned to each device on an IP network • IP: Internet protocol (IP) is the set of rules governing the format of data sent over IP networks. 5.9 References • https://www.geeksforgeeks.org/types-of-network-topology/ • https://www.javatpoint.com/computer-network-topologies • https://www.cloudflare.com/en-in/learning/network-layer/what-is-a-subnet/ • https://www.wpbeginner.com/glossary/ip-address/

87 UNIT - 6: STORAGE BASICS Structure 6.0 Learning Objectives 6.1 Introduction 6.2 Basics of storage 6.3 Basic Administration & Operation 6.4 Storage and Monitoring 6.5 Summary 6.6 Glossary 6.7 References 6.0 Learning Objectives After studying this unit, you will be able to • Define Storage • Identify the different types of storage • Recognise the features, vendor, etc. • Relate to the basic Administration & Operation of Storage and Monitoring 6.1 Introduction A storage unit is a part of the computer system which is employed to store the information and instructions to be processed. A storage device is an integral part of the computer hardware which stores information/data to process the result of any computational work. Without a storage device, a computer would not be able to run or even boot up. Or in other words, we can say that a storage device is hardware that is used for storing, porting, or extracting data files. It can also store information/data both temporarily and permanently. As computers advance, the technologies used to store data do too, with higher requirements for storage space. Because people need more and more space, want it faster, cheaper, and want to take it with them, new technologies have to be invented. When new storage devices are designed, as people upgrade to those new devices, the older devices are no longer needed and stop being used. For example, when punch cards were first used in early computers, the magnetic

88 media used for floppy disks was not available. After floppy diskettes were released, they were replaced by CD-ROM drives, which were replaced by DVD drives, which were replaced by flash drives. The first hard disk drive from IBM cost $50,000, was only 5 MB, big, and cumbersome. Today, we have smartphones that have hundreds of times the capacity at a smaller price that we can carry in our pocket. Each advancement of storage devices gives a computer the ability to store more data, and save and access data faster. 6.3 Basics of Storage Computer storage devices also known as digital storage, storage, storage media, or storage medium, a storage device is any hardware capable of holding information either temporarily or permanently. There are majorly two categories of storage devices used with computers: a primary storage device, such as RAM, and a secondary storage device, such as a hard drive. Secondary storage can be removable, internal, or external. Examples of computer storage-Today, there are three types of media storage used to store computer data: magnetic storage, optical storage, and solid-state storage. Without a storage device, a computer cannot save or remember any settings or information and would be considered a dumb terminal. Although a computer can run with no storage device, it would only be able to view information, unless it was connected to another computer that had storage capabilities. Even a task, such as browsing the Internet, requires information to be stored on your computer. Types of computer storages There are three types of storages • Primary storage • Secondary storage • Tertiary storage • Primary storage- It is also referred to as internal memory, is accessed by a computer's central processing unit (CPU). It is usually the fastest and most expensive type of memory in the computer. Primary storage uses random-access memory (RAM), cache memory, or some other specialized hardware to store data while the computer is powered on. When power is removed, RAM is wiped clean. The volatile nature of RAM means that additional storage devices are needed that continue to work when a computer is powered off. Examples of primary storages:

89 • Read Only Memory (ROM) • Random Access Memory (RAM) • Flash Memory • Cache Memory Primary Storage Secondary storage A secondary storage device refers to any non-volatile storage device that is internal or external to the computer. It can be any storage device beyond the primary storage that enables permanent data storage. A secondary storage device is also known as an auxiliary storage device, backup storage device, tier 2 storage, or external storage. These devices store virtually all programs and applications on a computer, including the operating system, device drivers, applications and general user data. The Secondary storage media can be fixed or removable. Fixed Storage media is an internal storage medium like a hard disk that is fixed inside the computer. A storage medium that is portable and can be taken outside the computer is termed removable storage media. The main advantage of using secondary storage devices is: • In Secondary storage devices, the stored data might not be under the direct control of the operating system. For example, many organizations store their archival data or critical documents on secondary storage drives, which their main network cannot access to ensure their preservation whenever a data breach occurs. • Since these drives do not interact directly with the main infrastructure and can be situated in a remote or secure site, it is unlikely that a hacker may access these drives unless they're physically stolen.

90 Computers use main memory such as random-access memory (RAM) and cache to hold data that is being processed. However, this type of memory is volatile, and it loses its data when the computer is switched off. General-purpose computers, such as personal computers and tablets, need to store programs and data for later use. Therefore, secondary storage is needed to keep programs and data long term. Secondary storage is non-volatile and able to keep data as long-term storage. They are used for various purposes such as backup data used for future restores or disaster recovery, long-term archiving of data that is not frequently accessed, and storage of non-critical data in lower-performing, less expensive drives. Types of Secondary Storage Device Here are the two types of secondary storage devices, i.e., fixed storage and removable storage. Types of Storages 1. Fixed Storage-Fixed storage is an internal media device used by a computer system to store data. Usually, these are referred to as the fixed disk drives or Hard Drives. Fixed storage devices are not fixed. These can be removed from the system for repairing work, maintenance purposes, and also for an upgrade, etc. But in general, this cannot be done without a proper toolkit to open up the computer system to provide physical access, which needs to be done by an engineer. Technically, almost all data, i.e., being processed on a computer system, is stored on some built-in fixed storage device. We have the following types of fixed storage: • Internal flash memory (rare) • SSD (solid-state disk) units • Hard disk drives (HDD)

91 2. Removable Storage Removable storage is an external media device that is used by a computer system to store data. Usually, these are referred to as the Removable Disks drives or the External Drives. Removable storage is any storage device that can be removed from a computer system while the system is running. Examples of external devices include CDs, DVDs, Blu-ray disk drives, and diskettes and USB drives. Removable storage makes it easier for a user to transfer data from one computer system to another. The main benefit of removable disks in storage factors is that they can provide the fast data transfer rates associated with storage area networks (SANs). We have the following types of Removable Storage: • Optical discs (CDs, DVDs, Blu-ray discs) • Memory cards • Floppy disks • Magnetic tapes • Disk packs • Paper storage (punched tapes, punched cards) Classification of Secondary Storage Devices The following image shows the classification of commonly used secondary storage devices. Secondary Storage Classification Tertiary storage: Tertiary storage is also known as nearline storage because it is \"near to online “, involves a robotic mechanism that will mount (insert) and dismount removable mass

92 storage media into a storage device according to the system's demands; such data are often copied to secondary storage before use. Typically, it involves a robotic mechanism which will mount (insert) and dismount removable mass storage media into a storage device • It is a comprehensive computer storage system that is usually very slow, so it is usually used to archive data that is not accessed frequently. • This is primarily useful for extraordinarily large data stores, accessed without human operators Removable Media Drives Examples: • Magnetic Tape • Optical Disc • Off-line Storage Magnetic Tape • A magnetically coated strip of plastic on which data can be encoded. • Tapes for computers are similar to tapes used to store music. • Tape is much less expensive than other storage mediums but commonly a much slower solution that is commonly used for backup. Optical Disc Optical disc is any storage media that holds content in digital format and is read using a laser assembly is considered optical media. The most common types of optical media are • Blu-ray (BD)

93 • Compact Disc (CD) • Digital Versatile Disc (DVD) Off-line Storage Also known as disconnected storage. • It is a computer data storage on a medium or a device that is not under the control of a processing unit. • It must be inserted or connected by a human operator before a computer can access it again. • It must be inserted or connected by a human operator before a computer can access it again. Examples: • Floppy Disk • Zip diskette • USB Flash drive 6.4 Basic Administration & Operation - Storage and Monitoring Storage Monitoring-Monitoring forms the basis for performing management operations. Monitoring provides the performance and availability status of various infrastructure components and services. It also helps to measure the utilization and consumption of various storage infrastructure resources by the services. This measurement facilitates the metering of services, capacity planning, forecasting, and optimal use of these resources. Monitoring events in the storage infrastructure, such

94 as a change in the performance or availability state of a component or a service, may be used to trigger automated routines or recovery procedures. • Configuration Monitoring • Availability Monitoring • Capacity Monitoring • Performance Monitoring • Security Monitoring Such procedures can reduce downtime due to known infrastructure errors and the level of manual intervention needed to recover from them. Further, monitoring helps in generating reports for service usage and trends. Additionally, monitoring of the data center environment parameters such as heating, ventilating, and air-conditioning (HVAC) helps in tracking any anomaly from their normal status. A storage infrastructure is primarily monitored for Monitoring Configuration-Monitoring configuration involves tracking configuration changes and deployment of storage infrastructure components and services. It also detects configuration errors, non-compliance with configuration policies, and unauthorized configuration changes. Monitoring Availability-Availability refers to the ability of a component or a service to perform its desired function during its specified time of operation. Monitoring availability of hardware components (for example, a port, an HBA, or a storage controller) or software component for example, a database instance or an orchestration software involves checking their availability status by reviewing the alerts generated from the system. For example, a port failure might result in a chain of availability alerts. A storage infrastructure commonly uses redundant components to avoid a single point of failure. Failure of a component might cause an outage that affects service availability, or it might cause performance degradation even though availability is not compromised. Continuous monitoring for expected availability of each component and reporting any deviation help the administrator to identify failing services and plan corrective action to maintain SLA requirements. Monitoring Capacity-Capacity refers to the total amount of storage infrastructure resources available. Inadequate capacity leads to degraded performance or even service unavailability. Monitoring capacity involves examining the amount of storage infrastructure resources used and usable such as the free space available on a file system or a storage pool, the numbers of ports available on a switch, or the utilization of allocated storage space to a service. Monitoring capacity helps an administrator to ensure uninterrupted data availability and scalability by averting outages before they occur. For example, if 90 percent of the ports are utilized in a particular SAN fabric,

95 this could indicate that a new switch might be required if more servers and storage systems need to be attached to the same fabric. Monitoring usually leverages analytical tools to perform capacity trend analysis. These trends help to understand future resource requirements and provide an estimation of the time required to deploy them. Monitoring Security-Monitoring a storage infrastructure for security includes tracking unauthorized access, whether accidental or malicious, and unauthorized configuration changes. For example, monitoring tracks and reports the initial zoning configuration performed and all the subsequent changes. Another example of monitoring security is to track login failures and unauthorized access to switches for performing administrative changes. IT organizations typically comply with various information security policies that may be specific to government regulations, organizational rules, or deployed services. Monitoring detects all operations and data movement that deviate from predefined security policies. Monitoring also detects unavailability of information and services to authorized users due to security breach. Further, physical security of a storage infrastructure can also be continuously monitored using badge readers, biometric scans, or video cameras. 2) Storage Alerting An alert is a system-to-user notification that provides information about events or impending threats or issues. Alerting of events is an integral part of monitoring. Alerting keeps administrators informed about the status of various components and processes. For example, conditions such as failure of power, storage drives, memory, switches, or availability zone, which can impact the availability of services and require immediate administrative attention. Other conditions, such as a file system reaching a capacity threshold, an operation breaching a configuration policy, or a soft media error on storage drives, are considered warning signs and may also require administrative attention. Monitoring tools enable administrators to define various alerted conditions and assign different severity levels for these conditions based on the impact of the conditions. Whenever a condition with a particular severity level occurs, an alert is sent to the administrator, an orchestrated operation is triggered, or an incident ticket is opened to initiate a corrective action. Alert classifications can range from information alerts to fatal alerts. Information alerts provide useful information but do not require any intervention by the administrator. The creation of a zone or LUN is an example of an information alert. Warning alerts require administrative attention so that the alerted condition is contained and does not affect service availability. For example, if an alert indicates that a storage pool is approaching a predefined threshold value, the administrator can decide whether additional storage drives need to be added to the pool. Fatal alerts require immediate attention because the condition might affect the overall performance or availability. For example, if a service fails, the administrator

96 must ensure that it is returned quickly. As every IT environment is unique, most monitoring systems require initial set-up and configuration, including defining what types of alerts should be classified as informational, warning, and fatal. Whenever possible, an organization should limit the number of truly critical alerts so that important events are not lost amidst informational messages. Continuous monitoring, with automated alerting, enables administrators to respond to failures quickly and proactively. Alerting provides information that helps administrators prioritize their response to events. 3) Storage Reporting-Like alerting, reporting is also associated with monitoring. Reporting on a storage infrastructure involves keeping track and gathering information from various components and processes that are monitored. The gathered information is compiled to generate reports for trend analysis, capacity planning, chargeback, performance, and security breaches. Capacity planning reports contain current and historic information about the utilization of storage, file systems, database tablespace, ports, etc. Configuration and asset management reports include details about device allocation, local or remote replicas, and fabric configuration. This report also lists all the equipment, with details, such as their purchase date, lease status, and maintenance records. Chargeback reports contain information about the allocation or utilization of storage infrastructure resources by various users or user groups. Performance reports provide current and historical information about the performance of various storage infrastructure components and services as well as their compliance with agreed service levels. Security breach reports provide details on the security violations, duration of breach and its impact. Reports are commonly displayed like a digital dashboard, which provide real time tabular or graphical views of gathered information. Dashboard reporting helps administrators to make instantaneous and informed decisions on resource procurement, plans for modifications in the existing infrastructure, policy enforcement, and improvements in management processes. 6.5 Summary • Storage unit is a part of the computer system which is employed to store the information and instructions to be processed. • Storage device is an integral part of the computer hardware which stores information/data to process the result of any computational work. • Storage in computer is of primary and secondary storages 6.6 Glossary • SSD: The SSD reads and writes data using flash memory

97 • Bandwidth: The amount of data that can be moved between two pieces of hardware in a given period of time. • Bus: A path in a computer used to move data. A data bus is described in terms of its width (in bits) and its speed (in megahertz). • Cache: A type of memory that holds recently accessed data, which is designed to speed up subsequent access to the same data. 6.6 References • https://www.techtarget.com/searchstorage/definition/storage • https://www.sciencedirect.com/topics/social-sciences/computer-storage-devices • https://www.dummies.com/article/technology/computers/basic-skills/computer- storage-202126 • https://testbook.com/learn/computer-storage-devices/

98 UNIT - 7: VIRTUALIZATION FUNDAMENTALS Structure 7.0 Learning Objectives 7.1 Introduction 7.2 Basics of Virtualization 7.3 Microsoft Virtualization Basics 7.4 Summary 7.5 Learning Activity 7.6 Glossary 7.7 References 7.0 Learning Objectives After studying this unit, you will be able to • Relate to the concept of Virtualization • Recall History of Virtualization • Identify Features, Vendors • Use Microsoft Virtualization products: ▪ Hyper-V ▪ ESX host ▪ VCentre 7.1 Introduction Today’s x86 computer hardware was designed to run a single operating system and a single application, leaving most machines vastly underutilized. Virtualization lets you run multiple virtual machines on a single physical machine, with each virtual machine sharing the resources of that one physical computer across multiple environments. Different virtual machines can run different operating systems and multiple applications on the same physical computer. While others are leaping aboard the virtualization bandwagon now, VMware is the market leader in virtualization. Our technology is production-proven, used by more than 170,000 customers, including