Overview of System Virtualization

Overview of System Virtualization

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  Andre Odendaal SYSTEM VIRTUALIZATION 1
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  Section Agenda • Definition • Real Benefits • History • Hypervisor Architecture • Hardware Virtualization Assistance • Considerations • Conclusion 2
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  Definition • Definition: Abstractionof the hardware resources into multiple execution environments • Comes from need to make more effective use of hardware • Approaches – Full - Hardware is completely emulated by the virtual machine – Paravirtualization - The virtual machine provides an API and the guest OS is modified to run on the virtual machine From Silberschatz, Galvin & Gagne Operating System Concepts © 2005 3
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  Real Benefits • Notjust for – Development & Testing – Consolidating physical servers • It’s a change in IT infrastructure – Creates hardware independence and mobility – Isolation from conflicts and service availability – Manage downtime and disaster recovery • Creating new opportunities From VMWare Virtualization Overview © 2006 – SaaS (Software as a Service) – IaaS (Infrasture as a Service) 4
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  History • 1964 -IBM developed Control Program-40 (CP-40) which emulated the System/360 architecture for multiple users. • 1972 – IBM released VM/370 for the System/370 which included virtual machine support, real device support and greater hardware exploitation. IBM also developed versions of MVS, UNIX, DOS/VSE and PC/DOS to run under VM • 1970’s – Virtualization is eclipsed by microcomputers • 1981 – IBM announced Extended Architecture (XA) which, among other things, had specialized I/O processors that were part of the hardware • 1999 - VMWare Workstation is released • 2001 - VMware ESX Server is released • 2003 - The first public release of Xen was made available • 2007 - Sun announced the Sun xVM • 2008 – Sun acquired VirtualBox 5
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  Hypervisor Technology • Apopular method of virtualization is paravirtualization using a hypervisor to manage the guest OS also called Virtual Machine Monitor (VMM) • The term hypervisor comes from the hyper call made by the guest OS to the virtual machine which is similar to a supervisor call made by an operating system to the Kernel • The hypervisor manages the operation levels of the guest OS by creating a virtual kernel mode and virtual user mode. Privileged instructions are paravirtualized and are validated and executed by the hypervisor on either the hardware or the host OS 6
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  Hypervisor Technology • Hosted – Hypervisor installed on host OS and manages guest OS – Provides the broadest range of hardware configurations • Hypervisor (Bare-metal) – First layer on top of the hardware – Provides greater scalability, robustness and performance From VMWare Virtualization Overview © 2006 7
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  Hardware Virtualization Assistance •Hardware can also be optimized for virtualization. Example include: – Virtual Memory – Memory Management Units – IO Virtualization • Hardware supporting virtualization – IBM – System/370 – Intel – x86 Intel VT – AMD – x86 AMD V – Sun – UltraSPARC 8
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  Hardware Virtualization Assistance •The Popek and Goldberg • Initially the x86 architecture Formal Requirements for was unsuitable for Virtualizable Third Generation virtualization Architectures are a set of – Ring compression (unable to requirements for sufficient change privilege level in 64-bit hardware virtualization mode) – Equivalence – A program – Ring aliasing (system calls running under VMM should reveal privilege level) exhibit the same behaviour if – Address Space Compression run on the machine directly (VMM address space isn’t – Resource Control – The VMM protected) should be in complete control – Non-Privileged Sensitive of the virtualized resources Instructions (some system calls – Efficiency – Major of machine are not privileged) instructions should be allowed – Silent Privilege Failures (some to execute with VMM system calls fail without intervention trapping) 9
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  Considerations • Management Complexity – Be prepared and have a plan – Make use of ITIL (Information Technology Infrastructure Library) for years of best practice • Pitfalls – Hardware Failure • All your eggs in one basket – Over commitment • Over or under use of resources – Operational Processors • VM sprawl vs. Server sprawl – Skills shortage • Virtualization requires specific skills (Configuration, Tuning & Troubleshooting) 10
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  Conclusion • Virtualization isa broad IT initiative • Requires management to be successful • Long history at all sectors of IT (Hardware, Operating System, Virtual Machines) 11
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  References • Bob DuCharmeThe Operating Systems Handbook © 2001 • Silberschatz, Galvin & Gagne Operating System Concepts © 2005 • VMWare Virtualization Overview © 2006 • IBM Introduction to the New Mainframe: z/VM Basics © 2007 • IBM IBM Systems Virtualization © 2005 • Barham, Dragovic, Fraser, Hand, Harris, Ho, Neugebauery, Pratt, Wa rfield Xen and the Art of Virtualization © 2003 • Fisher-Ogden Hardware Support for Efficient Virtualization • Business Trends Quarterly Virtualization: Big Picture Q1 2007 • Business Trends Quarterly The Pros and Cons of Virtualization Q1 2007 12
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  Questions Thank you 13