2010 VMware Inc. All rights reserved Virtualization and Cloud
Computing Vera Asodi VMware
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2 What is Virtualization? Virtualization is a technology that
allows you to transform hardware into software Virtualization
allows you to run multiple operating systems simultaneously on a
single computer
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3 History 1960s - IBM implemented virtualization as a way to
logically partition mainframe computers into separate virtual
machines to enable multitasking. 1960s - MIT Project MAC aimed to
design and implement a better time sharing system. 1990s VMware
invented x86 based architecture virtualization.
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4 Virtual Machine
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5 Traditional vs. Virtual Architecture Traditional
ArchitectureVirtual Architecture
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6 Benefits of Virtualization Encapsulation - VMs can be
described in a file Possible to snapshot Easy to move Enables
running multiple operating systems Consolidation & use of
unused computation power Resource management High availability
& disaster recovery Create Base Environment Safe testing of new
software Easy Management
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7 Virtual Center
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8 Types of Virtualization VMM Host OS VMM APP HostedBare Metal
APP VMware player VMware workstation Microsoft virtual PC Sun
VirtualBox QEMU KVM VMware ESX Microsoft Hyper-V XEN
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9 Virtualization installs like application rather than like OS
Can run alongside conventional applications Avoid code duplication
OS already has process scheduler, memory management, device support
etc. More suitable for personal users Better performance with lower
overhead Highly efficient direct I/O pass- through architecture for
network and disk Complete control over hardware Advanced features
like live migration available Suitable for production environments
Types of Virtualization (cont.) HostedBare Metal
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10 Running a VM The Virtual Machine Monitor (VMM) or Hypervisor
is the software layer that runs the VMs. There are several ways of
doing that.
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11 Emulation Emulation: Do what the CPU does in SW. Example:
addl %ebx, %eax is emulated as: enum {EAX=0, EBX=1, ECX=2, EDX=3,
}; unsigned long regs[8]; regs[EAX] += regs[EBX]; Pro: simple Con:
slow Instead of emulation, it would be more efficient to run the VM
directly on the host CPU.
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12 The Difficulty of Virtualization Traditional
ArchitectureBare Metal Virtualized Architecture Guest OS VMM User
Apps Host Computer System Hardware Ring 3 Ring 2 Ring 1 Ring 0 User
Apps Host Computer System Hardware Ring 3 Ring 2 Ring 1 Ring 0 OS
The problem: the guest OS runs in ring 1, while some privileged
instructions need to run in ring 0.
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13 Trap and Emulate Run the VM directly on the host CPU. Trap
and emulate sensitive instructions. Pros: Efficient Cons: Harder to
implement Need hardware support - not all sensitive instructions
cause a trap when executed in a non-privileged mode.
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14 Binary Translation Run the VM directly on the host CPU. The
VMM takes a block of binary instructions that are about to be
executed and dynamically translates it into safe instructions.
Translation: Most of the instructions translate identically.
Sensitive instructions are translated into safe ones. Pros: More
efficient than emulation No need for hardware support Cons: Less
efficient than trap and emulate Hard to implement
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15 Paravirtualization The OS of the VM is modified so that it
calls the hypervisor when it has to execute sensitive instructions.
Pros: Efficient No need for hardware support Cons: Need a modified
version of the guest OS, that is aware to the fact that it runs on
a VM.
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16 Running a VM - Summary Emulation and binary translation: No
need for modification of HW or guest OS. Emulation slow, binary
translation more efficient. Trap and emulate: HW modification is
required. Improved performance. Paravirtualization: OS modified and
aware. Improved performance. The technologies used in the industry
are mainly trap and emulate and binary translation, or a
combination of both.
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17 I/O Virtualization Types of I/O: Block (hard disk) Network
User input: keyboard, mouse Sound Video Most performance critical:
Block Network
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18 NIC Network Interface Card The NIC is responsible for
transmitting and receiving packets through the network. The packets
that are transmitted and received are written in the memory. There
are registers to which the driver writes the instructions to the
NIC. The NIC sends interrupts to the host when it finishes its
task.
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19 I/O Virtualization - Emulation Hypervisor implements a
virtual NIC (by the specification of a real NIC, e.g., Intel,
Realtek, Broadcom). NIC registers are variables. The hypervisor
passes the instructions to the registers of the physical NIC. When
physical NIC interrupts, hypervisor injects the interrupt into
guest. Hypervisor vNICs pNIC
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20 I/O Virtualization Emulation (cont.) Pros: Unmodified guest
(guest already has drivers for Intel NICs). Cons: Slow every access
to every NIC register causes a VM exit (trap to hypervisor).
Hypervisor needs to emulate complex hardware.
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21 I/O Virtualization - Paravirtualization Add virtual NIC
driver into guest (frontend). Implement the virtual NIC in the
hypervisor (backend). Everything works just like in the emulation
case except protocol between frontend and backend Hypervisor vNICs
pNIC
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22 I/O Virtualization Paravirtualization (cont.) Paravirtual
protocol: Instead of writing to registers, guest calls the
hypervisor, passes it start address and length as arguments
Hypervisor knows what it should do Paravirtual protocol can be
high-level, e.g., ring of buffers to transmit (so NIC doesnt stay
idle after one transmission), and independent of particular NIC
registers Pro: fast no need to emulate physical device Con:
requires guest driver
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23 I/O Virtualization Direct Access Pull NIC out of the host,
and plug it into the guest. Guest is allowed to access NIC
registers directly, no hypervisor intervention. Host cannot access
NIC anymore. Pros: As fast as possible Cons: Need NIC per guest
(plus one for host). Cannot encapsulate guest packets, monitor or
modify them at the hypervisor level. Hypervisor vNICs pNICs
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24 Hypervisor I/O Virtualization SR-IOV Single Root I/O
Virtualization Contains a physical function controlled by the host,
used to create multiple virtual functions. Each virtual function is
assigned to a guest (like in direct assignment). Each guest thinks
it has full control of the NIC, accesses registers directly (like
in direct access). The NIC does multiplexing/demultiplexing of
traffic. vNICs pNIC
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25 I/O Virtualization SR-IOV (cont.) Pros: As fast as possible
Need only one NIC (as opposed to direct assignment) Cons: Few
hypervisors fully support it Expensive Requires new hardware Cannot
encapsulate guest packets, monitor or modify them at the hypervisor
level.
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26 Live Migration
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27 Global Performance Optimization Heavy Load Lighter Load
Imbalanced Giant Computer Balanced Giant Computer
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28 PWRAPPs Global Power Optimization 20% Average Power
Savings
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29 Live Migration State 11 22 nn Continue until n is small
enough (depends on the desired downtime)
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30 HW/SW Separation
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31 Cloud Computing
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32 Cloud Computing Abstract the technology infrastructure The
user doesnt have to know There is a compute power out there
available for use Flexible * Dynamic * On Demand * Efficient
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33 Principles of Cloud Computing The user should focus on the
Application All the rest is taken care of by the Cloud Provider
Internal Cloud
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34 Types of Clouds SaaS Software as a Service IaaS
Infrastructure as a Service PaaS Platform as a Service
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35 SaaS Software as a Service Examples: Gmail, Salesforce.com
The cloud provider provides a SW that is available for use over the
internet. The user only pays for usage rather than buy the SW. The
user does not have to worry about installation, upgrades, and the
infrastructure needed for the SW.
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36 IaaS Infrastructure as a Service Example: Amazon EC2 The
cloud provider provides the user a computer with CPU, memory,
storage, network, etc. that is available for use through the
internet. The user pays for the CPU cycles and network usage. The
user does not have to buy the HW and provide the space, electricity
maintenance, etc. Very suitable for startups.
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37 PaaS Platform as a Service Example: Googles App Engine The
cloud provider provides not only the infrastructure but also the
application stack (e.g. JVM, web server, development and testing
tools). The user needs only to add the code.
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38 Benefits of Cloud Computing Tap into external computing
power quickly, as needed Accessible using standard internet
protocols Consumption based pricing - reduced costs Lower
maintenance costs High availability Scalability Improved economics
due to shared infrastructure Eco-friendly
