Transcript Virtualization

Virtualization and Cloud Computing
Vera Asodi
VMware
© 2010 VMware Inc. All rights reserved
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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History
 1960’s - IBM implemented virtualization as a way to logically partition
mainframe computers into separate virtual machines to enable
multitasking.
 1960’s - MIT – Project ‘MAC’ – aimed to design and implement a better
time sharing system.
 1990’s – VMware invented x86 based architecture virtualization.
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Virtual Machine
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Traditional vs. Virtual Architecture
Traditional Architecture
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Virtual Architecture
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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Virtual Center
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Types of Virtualization
Hosted
VMM
APP
Bare Metal
APP
Host OS
 VMware player
 Sun VirtualBox
 VMware workstation  QEMU
 Microsoft virtual PC  KVM
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VMM
 VMware ESX
 Microsoft Hyper-V
 XEN
Types of Virtualization (cont.)
Hosted
 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
Bare Metal
 Better performance with lower
overhead
 Highly efficient direct I/O passthrough architecture for network and
disk
 Complete control over hardware
 Advanced features like live migration
available
 Suitable for production environments
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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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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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The Difficulty of Virtualization
Traditional Architecture
Ring 3
User Apps
Bare Metal Virtualized Architecture
Ring 3
User Apps
Ring 2
Ring 2
Ring 1
Ring 1
Guest OS
Ring 0
VMM
Ring 0
OS
Host Computer
System Hardware
Host Computer
System Hardware
The problem: the guest OS runs in ring 1, while some privileged
instructions need to run in ring 0.
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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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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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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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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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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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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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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.
vNICs
 The hypervisor passes the instructions to the
registers of the physical NIC.
Hypervisor
 When physical NIC interrupts, hypervisor injects
the interrupt into guest.
pNIC
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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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I/O Virtualization - Paravirtualization
 Add virtual NIC driver into guest (frontend).
 Implement the virtual NIC in the hypervisor
(backend).
vNICs
 Everything works just like in the emulation
case…
Hypervisor
 …except – protocol between frontend and
backend
pNIC
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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 doesn’t 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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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.
vNICs
 Host cannot access NIC anymore.
Hypervisor
 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.
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pNICs
I/O Virtualization – SR-IOV
 Single Root I/O Virtualization
 Contains a physical function controlled by the
host, used to create multiple virtual functions.
vNICs
 Each virtual function is assigned to a guest (like
in direct assignment).
Hypervisor
 Each guest thinks it has full control of the NIC,
accesses registers directly (like in direct access).
 The NIC does multiplexing/demultiplexing of
traffic.
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pNIC
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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Live Migration
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PROC
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Global Performance Optimization
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Imbalanced
Balanced
Giant Computer
Heavy Load
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Global Power Optimization
20% Average
Power Savings
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HP
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ProLiant
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OVER
OVER
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TEMP
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2D 4B 6H 8F
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PLAYER
8F 6H 4B 2D
ONLINE
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DIMMS
9i 7C 5E 3G 1A
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1A 3G 5E 7C 9i
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Live Migration
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1
Continue until n
is small enough 2
(depends on the
desired downtime)
n
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State
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1
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POWER
SUPPLY
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1A 3G 5E 7C 9i
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ONLINE
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1
1
INTER
LOCK
DIMMS
9i 7C 5E 3G 1A
2D 4B 6H 8F
PROC
HP
ProLiant
DL380G6
2
OVER
TEMP
1A 3G 5E 7C 9i
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HW/SW Separation
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Cloud Computing
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Cloud Computing
 Abstract the technology infrastructure
 The user doesn’t have to know
 There is a compute power out there available for use
 Flexible * Dynamic * On Demand * Efficient
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Principles of Cloud Computing
Internal Cloud
 The user should focus on the Application
 All the rest is taken care of by the Cloud Provider
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Types of Clouds
 SaaS – Software as a Service
 IaaS – Infrastructure as a Service
 PaaS – Platform as a Service
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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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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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PaaS
 Platform as a Service
 Example: Google’s 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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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
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