Mike Meyers’ CompTIA Network+ ® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005 ) © 2012 The McGraw-Hill Companies, Inc. All

Mike Meyers’ CompTIA Network+® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005)

© 2012 The McGraw-Hill Companies, Inc. All rights reserved.

VirtualizationVirtualization

Chapter 17



ObjectivesObjectives• Describe the concepts of virtualization• Explain why PC and network administrators

have widely adopted virtualization• Describe how virtualization manifests in

modern networks



OverviewOverview



Introduction to virtualizationIntroduction to virtualization

• Virtualization is the “next big thing” in the computer industry– Virtualization creates a complete environment for a

guest operating system to function as if it were installed on its own computer

– Guest environment is called a virtual machine (VM) – Individual machines or entire networks can be

virtualized



Figure 17.1 VM running Linux



Three parts to Chapter 17Three parts to Chapter 17

• What is virtualization?• Why do we virtualize?• Virtualization in modern networks



What is virtualization?



• What is virtualization?– Most people have heard of “virtual reality”

• “Virtual” world created by software, with sight & sound provided by video and audio equipment

• Primarily used for gaming, flight simulation, etc.• Equipment such as goggles and special gloves

enable you to “see” and “move” objects– Computer virtualization is similar

• “Virtual” operating system



Figure 17.2 Virtual reality training



Figure 17.3 Using virtual reality to practice spacewalking(Image courtesy of NASA)



• Computer virtualization– “Virtualizes” computers and networks

• Virtualization convinces an operating system that it’s running on its own hardware

• Runs on a host operating system that physically is installed on a machine

• Guest operating systems are the virtual ones• Uses hypervisors or virtual machine managers to

create and manage virtual machines and their interactions with their host environments



• Meet the hypervisor– Single OS uses program called a supervisor

• Handles very low-level interaction among hardware and software (i.e., task scheduling, allotment of time and resources, etc.)

– Full virtualization requires an extra layer of programming to manage complex interactions of hosts and guest machines

– Enter the hypervisor or virtual machine manager (VMM).



• Meet the hypervisor (cont.)– Hypervisor handles input and output

requests an operating system would make of normal hardware

– Allocates real hardware to virtual machines (drives, RAM, media, etc.) in a balance with each other and the host

– Enables easy addition and removal of virtual hard drives, virtual network cards, virtual RAM, etc.



Figure 17.4 Configuring virtual hardware in

VMware Workstation



Figure 17.5 Configuring virtual hardware in Microsoft’s Virtual PC



• Emulation vs. virtualization– Virtualization uses hardware from the host

system and divides it into individual virtual machines

• Abstracts hardware that is the same platform• Cannot virtualize hardware for a different platform

(Intel vs. a Sony PlayStation) for a VM– Emulation is very different

• Enables software written for a different platform to run – does not virtualize hardware



• Emulation vs. virtualization (cont.)– An emulator is software or hardware that

converts the commands to and from the host machine into an entirely different platform

• For example, running game console software on a PC



Figure 17.6 Emulator running on Windows



• Sample virtualization– Following slides take you through a quick

tour of virtualization• Setting up and installing a virtual machine and its guest OS

– Uses Windows 7 as the host OS– Uses VMware Workstation as the VMM– Installs Ubuntu as the guest OS



Figure 17.7 VMware Workstation



Figure 17.8 Selecting a Typical or Custom setup



Figure 17.9 Installation media



Figure 17.10 Setting the virtual drive size



Figure 17.11 Entering VM name and location



Figure 17.12 Ubuntu installing into the new virtual machine



Figure 17.13 VMware Workstation with a single VM



Figure 17.14 POST in a virtual machine



Why do we virtualize?



• Why do we virtualize?– Two important reasons:

• Reduce number of physical machines• Ease of managing virtual machines as files (backups,

security, portability, etc.)– Other important reasons include:

• Power saving• Hardware consolidation• System recovery• System duplication• Research



• Power saving– Before virtualization, each server OS needed

to be on a unique physical system– With virtualization, you can place multiple

virtual servers on a single physical system, reducing electrical power use

– Expanding this electricity savings over an enterprise network or on a data center is cost effective and “green”



• Hardware consolidation– Not cost effective to use a high-end server

with multiple processors, RAID arrays, redundant power supplies, and RAM for only one server

– Virtualization makes it possible to increase RAM and run a number of servers on a single server



• System recovery– The most popular reason for virtualization is

to keep a high uptime percentage– If a system goes down, you need to quickly

restore the system from a backup– Virtualization makes it possible to shut down

the VM and reload an alternative copy– Snapshots enable you to make a point-in-

time exact copy of the virtual machine that can be used in case of an emergency restore



Figure 17.15 Saving a snapshot



• System duplication– Takes advantage of the fact that VMs are

simply files that can be copied– VMs can be mass-duplicated by copying the

files to the target machine– Useful for:

• Mass-deploying numerous servers with similar baseline operating systems

• Lab or teaching environments



• Research– Offers opportunity to reduce research and

testing machines through virtualization– Useful for:

• Product testing and research• Security testing and research• Development testing before production



Figure 17.16 Lots of VMs used for research



Virtualization in modern networks



• Virtualization in modern networks– Products discussed so far offer virtualization

over operating systems• VMware Workstation• Microsoft Virtual PC

– Suitable for small implementations with few virtual machines

– Large-scale implementations require a different approach



• Virtualization in modern networks (cont.)– Virtualization in large-scale networks uses

“bare metal” hypervisors• No operating system necessary• Virtualization software IS the OS• Eliminates all the unnecessary OS overhead

– VMware introduced ESX in 2001• Early serious large-scale bare metal hypervisor• Small storage footprint – can be installed on and

booted from a USB flash drive



Figure 17.17 USB drive on server system



• VMMs vs. hypervisors– Virtual machine managers (VMMs) are

virtual machine software that runs on top of a host operating system

• Example is VMware Workstation – Hypervisor is software that does not need a

host operating system• Example is ESX Server



• Virtual machine managers– Many choices available for Linux, Windows,

and Mac OS:• VMware Workstation• Microsoft Virtual PC• Parallels• KVM



• VMware Workstation– Industry leader in virtualization– Comes in versions for Linux and Windows– Offers features such as VMTools that make

interactions between guest and host OS seamless



• Virtual PC– Microsoft VMM that runs over various

iterations of Windows– Free product– Some limitations

• Officially supports Windows VMs, but Linux VMs can be installed and managed



Figure 17.18 Windows Virtual PC



• Parallels– Most popular virtualization manager for

Mac OS X (followed by VMware Fusion)– Supports all popular operating systems,

and even has good 3D graphics support



Figure 17.19 Parallels for Windows



• KVM– Open-source virtualization product

from Red Hat– Represents Linux/Unix world– Supports a few non-x86 processors – Other open-source contenders include

Xen and Sun’s VirtualBox



• Hypervisors– Several choices, but there are two dominant

heavyweights in market:• VMware’s ESX• Microsoft’s Hyper-V



• ESX– Market leader; offers several features:

• Support for large storage (SAN and NAS)• Transparent and automatic fault tolerance• Transparent move of running VM from one server to

another• Support for up to 32 CPUs, depending on version



• Hyper-V– Microsoft’s contender in virtualization

• Free product• Previously only part of Windows Server 2008 – now

also available as stand-alone product • Available for 64-bit systems



• Virtual switches– Addresses problems with multiple VMs,

but limited NICs on host– Allows all VMs to communicate with each

other, the host, and the network (and Internet)

– All get their own IP address information– Two primary methods: bridging and virtual

switching



• Virtual switches (cont.)– Bridging gives each virtual NIC a connection

to the real NIC• Alternative method of bridging is to install physical

NICs for each VM – each virtual NIC gets a connection to its own dedicated physical NIC

– Virtual switch enables VMs to communicate only with each other with no outside connection



Figure 17.20 Bridged NICs



Figure 17.21 Dedicated bridged NICs



Figure 17.22 Virtual switch



• Virtual PBX– Older hardware PBX boxes replaced with

“virtual” ones– Virtual PBX is software running on a

computer– All the benefits of virtualization– Many popular PBX software applications– Also “cloud” versions of virtual PBX



Figure 17.23 Asterisk running on a system



• Network as a Service (NaaS)– Cloud service offering virtualized networks,

servers, and services– Saves on reduced infrastructure and

hardware costs – costs pennies on the dollar– Ideal for small businesses that need a large

network service

Documents

Mike Meyers’ CompTIA Network+ ® Guide to Managing and Troubleshooting Networks, Third Edition (Exam N10-005 ) © 2012 The McGraw-Hill Companies, Inc. All