Operating System Virtualization

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Operating System Virtualization

• Adam Nofsinger

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OS Virtualization

• What is it?
• Brief History
• Why use it?
• Virtualization Software
• Shortcomings
• Future Tech

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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

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Virtualization

• OS Virtualization (Virtual Machines)
• Separate OS from Physical Hardware
• Host OS ? Guest OS

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Virtualization Techniques

• How does Guest OS get to Hardware?

Guest OS
Virtual Layer
Host OS
Hardware Processor Memory NIC Disk
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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
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Virtualization Techniques

• Hypervisor
• Vmware ESX Server, Parallels

OS
OS
OS
Hypervisor Software
Hardware
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Virtualization Techniques

• Para-Virtualization
• Xen, Vmware Tools

Guest OS (Modified)
Guest OS (Modified)
Guest OS (Modified)
Virtual Monitor
Host OS
Hardware
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One Slide History

• 1960s
• IBMs 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

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Why OS Virtualization?

• Multi-Platform Testing
• 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

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Why OS Virtualization?

• Isolation
• Virtual Machine from Host OS / Other VMs
• Safe for untrusted applications.
• Partitioning of Services
• Server Environment more stable.
• Some Applications dont play w/ Others
• Encapsulation
• One VM ? One File/Folder on Disk
• Typically easy to migrate.

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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

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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.

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Virtualization Software

• Vmware
• Server
• Player
• Workstation
• ESX Server
• Qemu
• Xen
• Microsoft Virtual PC/Server
• Connectix

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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

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Vmware Player

• Demo Time!

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Vmware WorkStation

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

http//www.vmware.com/img/ws5_large4.png
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http//www.vmware.com/img/ws5_large3.png
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Vmware ESX Server

• Intended for Enterprise-Level Servers
• Partitioning
• Hypervisor
• Runs on Bare Metal (Hardware Layer)
• Live Migration

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QEMU

• Demo Time!

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Xen

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

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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)

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Other Offerings

• Bochs IA-32 Emulator
• http//bochs.sourceforge.net/
• Linux-VServer
• http//linux-vserver.org/
• Virtuozzo gt Server Virtualization, 200 -
  4000
• http//www.swsoft.com/en/products/virtuozzo/
• OpenVZ gt Open Source Virtuozzo
• http//openvz.org/
• Parallels Workstation 2.0 gt Hypervisor-Powered,
  49 / license
• http//www.parallels.com/
• TRANGO RTOS Hypervisor, ARM, MIPS, PowerPC,
  etc.
• http//www.trango-systems.com/

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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

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General Shortcomings

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

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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
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Future Tech

• AMD VT (aka Pacifica)
• Similar to Intel
• Additions to x86 Architecture to better support
  VMs

http//enterprise.amd.com/Downloads/Pacifica_en.pd
f
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References

• Amit Sing, An Introduction to Virtualization
• http//www.kernelthread.com/publications/virtuali
  zation/
• Vmware, Virtualization Overview
• http//www.vmware.com/virtualization/
• Vmware, Virtualization White Paper
• http//www.vmware.com/pdf/virtualization.pdf
  pdf
• Cambridge University Systems Research Group, Xen
  Website
• http//www.cl.cam.ac.uk/Research/SRG/netos/xen/
• Microsoft, Virtual PC Website
• http//www.microsoft.com/windows/virtualpc/default
  .mspx
• Bochs Website
• http//bochs.sourceforge.net/
• Gabriel Torres, Intel Virtualization Technology
  (VT) Explained
• http//www.hardwaresecrets.com/printpage/263
• AMD, Pacifica Virtualization Technology
• http//enterprise.amd.com/Downloads/Pacifica_en.pd
  f pdf