1. Virtualization
Chapter 30

2. Overview In this chapter, you will learn how to
Describe the concepts of virtualization
Explain why PC and network administrators have widely adopted virtualization
Describe how virtualization manifests in modern networks 2

3. Introduction 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.

4. Introduction to Virtualization (continued)
Figure 1 shows one such example: a system running Windows 7 using a program called VMware Workstation to host a virtual machine running Ubuntu Linux.
Figure 1: VMware running Linux

5. What Is Virtualization?

6. What Is Virtualization?
Most people have heard of “virtual reality.”
A “virtual” world is 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 enables you to “see” and “move” objects.
Computer virtualization is similar
“Virtual” operating system
Software computer (guest) running on hardware host
Allows multiple different operating systems to run

7. What Is Virtualization? (continued)
For most of us, the idea of virtual reality starts with someone wearing some kind of headgear and gloves, as shown in Figure 2.
Figure 2: Virtual reality training (photo courtesy of NASA)

8. What Is Virtualization? (continued)
Uses for virtual reality include teaching someone how to fly a plane or do a space walk without having to do the real thing at the beginning (Figure 3).
Figure 3: Using virtual reality to practice spacewalking (photo courtesy of NASA)

9. Computer Virtualization
Similarly, computers and networks can be virtualized.
Virtualization convinces an operating system that it’s running on its own hardware.
The virtualization software runs on a host operating system that is physically installed on a machine.
The guest operating systems are the virtual machines.
Virtualization uses hypervisors or virtual machine managers to create and manage virtual machines and their interactions with their host environments.

10. Meet the Hypervisor A normal OS uses a 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 the complex interactions between the host and guest machines.
Enter the hypervisor or virtual machine manager (VMM).

11. Meet the Hypervisor (continued)
The hypervisor handles the input and output requests an operating system would make of normal hardware.
It allocates real hardware (drives, RAM, media, etc.) from the host to the virtual machines.
It enables easy addition and removal of virtual hard drives, virtual network cards, virtual RAM, etc.
Note that the host machine allocates real RAM and CPU time to every running virtual machine. If you want to run a number of virtual machines at the same time, make sure your host machine has plenty of CPU power, and more importantly, plenty of RAM to support all the running virtual machines!

12. Meet the Hypervisor (continued)
Figure 4 shows the Hardware Configuration screen from VMware Workstation.
Figure 4: Configuring virtual hardware in VMware Workstation

13. Meet the Hypervisor (continued)
Virtualization even goes so far as to provide a virtualized BIOS and System Setup for every virtual machine. Figure 5 shows another popular virtualization program, Microsoft’s Virtual PC, showing the System Setup, just as you’d see on a regular computer.
Figure 5: System setup utility in VMware Workstation

14. Emulation versus Virtualization
Virtualization uses hardware from the host system and divides it into individual virtual machines.
It abstracts hardware that runs on the same platform.
It cannot virtualize hardware that is on a different platform (an Intel platform cannot virtualize a Sony PlayStation).
Emulation is very different.
It enables software written for a different platform to run, but it does not virtualize the hardware.

15. Emulation versus Virtualization (continued)
An emulator is software or hardware that converts the commands to and from the host machine into an entirely different platform.
For example, an emulator makes it possible to run game console software on a PC.

16. Emulation versus Virtualization (continued)
Figure 6 shows a typical emulator, Snes9X, running a game called Donkey Kong Country on a Windows system.
Figure 6: Super Nintendo emulator running on Windows

17. Sample Virtualization
The following slides take you through a quick tour of virtualization.
They show the steps involved in setting up and installing a virtual machine and its guest OS.
In this example, Windows 7 is the host OS.
VMware Workstation is the VMM.
Ubuntu is installed as the guest OS.
In this example, we’ll use the popular VMware Workstation on a Windows 7 system and create a virtual machine running Ubuntu Linux.

18. Sample Virtualization (continued)
Begin by obtaining a copy of VMware Workstation. This program isn’t free, but VMware will give you a 30-day trial. Go to to get yourself a trial copy. A freshly installed copy of VMware Workstation looks like Figure 7.
Figure 7: VMware Workstation

19. Sample Virtualization (continued)
Clicking on New Virtual Machine prompts you for a typical or custom setup (Figure 8). These settings are only for backward compatibility with earlier versions of VMware, so just click Next.
Figure 8: Selecting a Typical or Custom setup

20. Sample Virtualization (continued)
Because virtual machines are so flexible on hardware, VMware Workstation enables you to use either the host machine’s optical drive or an ISO file. I’m installing Ubuntu, so I downloaded the latest ISO image from the Ubuntu website ( and as Figure 9 shows, I’ve pointed the dialog box to that image.
Figure 9: Selecting the installation media

21. Sample Virtualization (continued)
Because VMware knows this operating system, it will automatically configure all of the virtual hardware settings—amount of RAM, virtual hard drive size, etc. You can change any of these settings, either before the virtual machine is created or at any time later. Refer back to Figure 5 to see these settings. You need to accept the size of the virtual drive, as shown in Figure 10.
Figure 10: Setting the virtual drive size

22. Sample Virtualization (continued)
Note that VMware uses a folder off the User’s Documents folder called Virtual Machines (Figure 11).
Figure 11: Entering the VM name and location

23. Sample Virtualization (continued)
VMware is very convenient, even ensuring the boot order in the virtual system setup is configured to boot first from the installation media, making the Ubuntu installation automatic (Figure 12).
Figure 12: Ubuntu installing into the new virtual machine

24. Sample Virtualization (continued)
Figure 13 shows VMware Workstation with the single VM installed but not running.
Figure 13: VMware Workstation with a single VM

25. Sample Virtualization (continued)
A VM goes through a POST process just like any computer, as shown in Figure 14. If you wish, you can even access a complete virtual System Setup by pressing the DELETE key, just as you would on a physical system.
Figure 14: POST in a virtual machine

26. Why Do We Virtualize?

27. Why Do We Virtualize? Virtualization provides two key benefits:
It reduces the number of physical machines.
Virtual machines are simply files, making it easy to manage backups, security, portability, etc.
Other important reasons include:
Power savings
Hardware consolidation
System recovery
System duplication
Research

28. Power Savings
Before virtualization, each server OS required its own 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.”

29. Hardware Consolidation
A physical high-end server represents a substantial investment in hardware— multiple processors, RAID arrays, redundant power supplies, and RAM. Setting up multiple physical high-end servers can be very expensive.
Virtualization makes it possible to increase RAM and run a number of servers on a single machine.

30. 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.

31. System Recovery (continued)
Figure 15 shows VMware's Workstation saving a snapshot.
Figure 15: Saving a snapshot

32. System Duplication VMs are simply files that can be copied.
VMs can be mass-duplicated by copying the files to the target machine.
This makes it possible to deploy numerous servers with similar baseline operating systems.
Useful in research or teaching environments

33. Research
Virtualization makes it possible to reduce the number of research and testing machines.
It can streamline the equipment necessary in these areas:
Product testing and research
Security testing and research
Development testing before production

34. Research (continued) Figure 16: Lots of VMs used for research
Today, a single hypervisor can support a large number of Windows versions on a single machine (Figure 16).
Figure 16: Lots of VMs used for research

35. Virtualization in Modern Networks

36. Virtualization in Modern Networks
The products we’ve discussed so far offer virtualization over operating systems:
VMware Workstation
Microsoft Virtual PC
They are suitable for small implementations with few virtual machines.
Large-scale implementations require a different approach.

37. Virtualization in Modern Networks (continued)
Virtualization in large-scale networks uses “bare metal” hypervisors.
No operating system is necessary.
The virtualization software IS the OS.
The hypervisor eliminates all the unnecessary OS overhead.
VMware introduced ESX in 2001.
It was an early serious large-scale bare-metal hypervisor.
It has a small storage footprint and can be installed on and booted from a USB flash drive.

38. Virtualization in Modern Networks (continued)
Figure 17 shows how we load our copy of ESX: via a small USB thumb drive. Power up the server, the server loads ESX off the thumb drive, and in short order a very rudimentary interface appears where we can input essential information, such as a master password and a static IP address.
Figure 17: USB drive on server system

39. VMMs vs. Hypervisors
A virtual machine manager (VMM) is virtual machine software that runs on top of a host operating system.
Example: VMware Workstation
A hypervisor is software that does not need a host operating system.
Example: ESX Server
These are also sometimes referred to as Type 1 hypervisors (ESX and Hyper-V) and Type 2 hypervisors, which are also called VMMs (VMware Workstation, VirtualPC, and Sun’s VirtualBox).
Other writers call both the hosted and bare-metal—or native—virtualization software products hypervisors, but make a distinction in other descriptive words (such as hosted or native).

40. Virtual Machine Managers
Many choices available for Linux, Windows, and Mac OS:
VMware Workstation
Microsoft Virtual PC
Parallels
KVM

41. Virtual Machine Managers (continued)
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

42. Virtual Machine Managers (continued)
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

43. Virtual Machine Managers (continued)
Figure 18: Windows Virtual PC

44. Virtual Machine Managers (continued)
Parallels
Most popular virtualization manager for Mac OS X (followed by VMware Fusion)
Supports all popular operating systems and even has good 3-D graphics support

45. Virtual Machine Managers (continued)
Figure 19: Parallels for Mac

46. Virtual Machine Managers (continued)
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 Oracle’s VirtualBox

47. Hypervisors
There are several choices, but two are dominant in the market:
Vmware’s ESX
Microsoft’s Hyper-V

48. Hypervisors (continued)
ESX
Market leader; offers several features:
Support for large storage (SAN and NAS)
Transparent and automatic fault tolerance
Transparent server transfer—you can move a running VM from one machine to another
Support for up to 32 CPUs, depending on the version
• Interface with large storage—ESX virtual machines easily integrate with NAS and SANs to handle massive data storage.
• Transparent fault tolerance—ESX can monitor and automatically recover failed VMs with little or no input.
• Transparent server transfer—You can move a running VM from one machine to another.
• High virtual CPUs—Most hypervisors support a limited number of virtual CPUs, usually two at most. ESX can support up to 32 CPUs, depending on the version of the vSphere product you purchase to support it.

49. Hypervisors (continued)
Microsoft’s contender in virtualization
Free product
Previously only part of Windows Server 2008—now also available as standalone product
Available for 64-bit systems