1. Operating System Virtualization
Adam Nofsinger

2. OS Virtualization What is it? Brief History Why use it?
Virtualization Software
Shortcomings
Future Tech

3. Virtualization Definition:
Broadly describes the (beneficial) separation of a resource or service from the typical physical means of providing it.
Examples:
Virtual Memory
Virtual Private Networks
Java Virtual Machine

4. Virtualization OS Virtualization (Virtual Machines)
Separate OS from Physical Hardware
Host OS  Guest OS
Host OS
Guest OS
Virtual Layer
Hardware

5. Virtualization Techniques
How does Guest OS get to Hardware?
Guest OS
Virtual Layer
Host OS
Hardware
Processor – Memory – NIC – Disk

6. Virtualization Techniques
Virtual Monitor
Qemu, Vmware Player, Microsoft Virtual PC
Sometimes called Emulation, e.g. x86 Emulation
Guest OS
Guest OS
Guest OS
Virtual Monitor
Host OS
Hardware

7. Virtualization Techniques
Hypervisor
Vmware ESX Server, Parallels* OS OS OS
Hypervisor Software
Hardware

8. Virtualization Techniques
Para-Virtualization
Xen, Vmware Tools*
Guest OS
(Modified)
Guest OS
(Modified)
Guest OS
(Modified)
Virtual Monitor
Host OS
Hardware

9. One Slide History 1960s 1980s 1990s - Present
IBM’s Mainframe Computers (e.g. IBM S/360)
Compatible Time Sharing System (CTSS)
1980s
Desktop PC  Virtualization on Backburner
1990s - Present
IA-32 Server Hardware  High Profit Market
Virtualization  Increased Hardware value.
Vmware Introduces Workstation

10. Why OS Virtualization? Multi-Platform Testing Emulated Hardware
Only need one set of Hardware
Resource saver on purchases (time/money)
Can cut setup time
Emulated Hardware
Same Hardware on All Test Environments
Hardware Simulation
Limited Resource Environments

11. Why OS Virtualization? Isolation Encapsulation
Virtual Machine from Host OS / Other VMs
Safe for “untrusted” applications.
Partitioning of Services
Server Environment more stable.
Some Applications don’t play w/ Others
Encapsulation
One VM  One File/Folder on Disk
Typically easy to migrate.

12. Why OS Virtualization? OS Debugging
Crash on Developing OS do not (typically) affect Host OS.
Debug
Memory dumps
CPU Registers
Serial / Parallel Port dumps
Multiple OS Instances Simultaneously
Infrastructure Testing
Win 98  Linux  OpenBSD  Win 2K

13. Why OS Virtualization? Legacy Applications
Server Application Virtualization Testing
Some application commonly on VMs
Portability Requirements Lessen
Down with Host OS!
Virtualization is Fun!
Gain Experience with new OS.
Help a business transition to Open-Source.

14. Virtualization Software
Vmware
Server
Player
Workstation
ESX Server
Qemu
Xen
Microsoft Virtual PC/Server
Connectix

15. Vmware Server Currently Free! (But Geared toward Server)
Unique Features vs. Workstation
Remote Administration
Consoles
Web Interface
VMs can Run as Service
Slow to Administrate
Especially GUI style (e.g. X, Windows)
Can make VMs for Vmware Player

23. Vmware Player
Demo Time!

24. Vmware WorkStation Geared more toward Software Developers
Features vs. Vmware Server
Multiple Snapshots
Cloning
Movie Recording
Teams & VPNs
$200/license

26. Vmware ESX Server Intended for Enterprise-Level Servers Hypervisor
Partitioning
Hypervisor
Runs on “Bare Metal” (Hardware Layer)
Live Migration

27. QEMU
Demo Time!

28. Xen Open-Source, Linux Para-Virtualization Live Migration Very Fast
Have to use Modified Guest OS
Kernel Modifications
Windows?
Live Migration

29. Microsoft Virtual PC / Server
The VM Software Formerly Known as Connectix Virtual PC
Runs on x86 or Power PC Architecture
PC: $130
Server: $100 - $200 (#of processor)

30. Other Offerings Bochs IA-32 Emulator http://bochs.sourceforge.net/
Linux-VServer
Virtuozzo => Server Virtualization, $200 - $4000+
OpenVZ => Open Source Virtuozzo
Parallels Workstation 2.0 => Hypervisor-Powered, $49 / license
TRANGO – RTOS Hypervisor, ARM, MIPS, PowerPC, etc.

31. General Shortcomings
Virtual Machine cannot represent real scenario 100% accurately.
Especially true with Para-Virtualization.
Most situations  close enough.
Guest OS Hardware Requirements.
Host needs more RAM, HD Space, etc.
Sometimes just to operate

32. General Shortcomings Intel IA-32  Virtualization Problems
More on this in a bit (Vanderpool)
Some Hardware not supported
USB (Sometimes)
3D Graphics Cards
Etc.

33. Future Tech Intel VT (aka “Vanderpool”)
Virtual Machine Extensions (VMX)
10 new virtualization specific instructions
VMXON, VMXOFF
VMLAUNCH, VMRESUME
BIOS / VMM application in the works OS OS OS
Virtual Layer
Virtual CPU
Virtual CPU
Virtual CPU

34. Future Tech AMD VT (aka “Pacifica”) Similar to Intel
Additions to x86 Architecture to better support VMs

35. References Amit Sing, An Introduction to Virtualization
Vmware, Virtualization Overview
Vmware, Virtualization White Paper
[pdf]
Cambridge University Systems Research Group, Xen Website
Microsoft, Virtual PC Website
Bochs Website
Gabriel Torres, Intel Virtualization Technology (VT) Explained
AMD, “Pacifica” Virtualization Technology
[pdf]