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Buddhika Siddhisena Co-Founder & CTO
THINKCube SystemsMember of LKLUG
VirtualizationThe future of computing
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What is Virtualization?
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What is Virtualization – Short
● Simple term word for a simple idea ● Run multiple “Operating System” instances
(Virtual Machines) on one physical computer● Virtualize the same OS or different OSes● Encapsulates a series of buzz words – Hypervisor,
Para virtualization, Virtual Machine, Emulation,Simulation
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WHAT is Virtualization Technology
● Virtualization Technology (VT) is an old technology thathas been revitalized recently, thanks to faster processorincrease in processing power.
● Virtualization is often achieved by either totally orpartially emulating the processor, BIOS and otherhardware devices.
● Emulating a completely different processor architectureis much slower since CPU instructions need to beemulated, compared to a native emulation.
● Guest OS is unaware of the emulation and is led tobelieve that it has the resources of the entire machineunder its control.
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WHAT is Virtualization Technology
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Some popular Emulators● Qemu is an FOSS x86/x86_64,ARM,PowePC etc. CPU emulator.
● Kvm is an extended version of Qemu to support hardware virtualization
● Bochs is an x86/x86_64 emulator that is FOSS
● Mac-on-Linux is a PPC emulator which uses native cpu emulation
● UML (User Mode Linux) enables a Linux kernel to run inside anotherLinux system as a user space application.
● PearPC is an Open Source PPC G4 emulator.
● VirtualBox is now Open Source
●VMWare a commercial, free for personal user, x86 emulator that usesnative cpu emulation
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Why Virtualize?
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Why Virtualize - Simply
Save Money $$$
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WHY Virtualize (Advantages)
● Better utilization of hardware. Today on anaverage, Servers run at less that 15% utilization.
● Better scalability. Dynamic scalability.
● Better maintainability. Lesser down time.
● Better fault tolerance.
● Better deployment / roll out. ISP now providevirtual root hosting within minutes.
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Who uses Virtualization?
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● Amazon EC2 , Google AppEngine (CloudComputing)
● Data Centers● Hosting Providers - Virtual Server● NOC● Desktop Users● You and Me
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Para Virtualization (Xen)
● In Para-Virtualization the Guest OS is ported to an idealplatform.● The Hypervisor platform provides an API which themodified kernel of the GuestOS ends up calling when tryingto access hardware.● Device drivers are virtualized by running the part thatinteracts with the device (physical driver) in a separatedomain known as Domain0.● Virtual environments are created in a separate DomainUthat doesn't have direct access to hardware.●DomainU kernels communicate with the Domain0 kernelto access hardware.
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Para Virtualization: Xen
● Xen runs at ring 0 where the normal OS would run
● Xen starts guestOS domain0 and domainU at ring 1
● User applications of the guestOS runs at ring 3
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Advantages of Para-Virtualization
High performance, often close to native speed, slowest being8% of native speed.
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Advantages of Para-Virtualization
Live migration of a VM to another physical machine with onlya few milliseconds of downtime (<100ms).
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Disadvantages of Para-Virtualization
● Guest OS should be modified to support the Para-Virtualizationplatform. Fortunately this only requires the kernel to be ported tothe platform and the applications can remain untouched. Not aproblem for an Free/Open Source OS. Now with direct hardwaresupport using Intel's VT / AMD's Pacific.● Currently X-windows only works at on Domain0 and fails at otherdomains as it requires access to the video card hardware. It is stillpossible to run X applications that is within a DomainU VM byusing a remote desktop app such as VNC. Again not a problem withVT technlogies.
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Enter FULL virtualization(Hardware virtualization)
Intel (Intel-VT) and AMD (AMD-V) nowfully support virtualization at a hardware
levelLinux Kernel officially supports Full VT via
kvm
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Software virtualization(multi-tenant virtualization)
More cost effective and scalableModify Application to support multiple
instancesSecurity is the applications responsibility
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Thank You
Use the force, read the source!