Cloud Computing – UNIT - II

VIRTUALIZATION

Virtualization

• Hiding the reality • The mantra of smart computing is to

intelligently hide the reality• Binary-> Assembly->High level• UI hides the business logic• DNS names hide the IP addresses• URL hides the web resource• API hides functionality• JVM hides the intermediate code

Before we understand Virtualization

• How do you run Multiple Operating Systems on the same box?

• Can they interact with each other ?• Can they share each other’s resources such as

memory, hard disk, network etc ?• Can you run all of them together (in one

shot?)• How easy it is to switch between them ?

STEP BY STEP UNDERSTANDING OF

VIRTUALIZATION

Hard Disk Partitioning

WIN 7

UBUNTU

RED HAT

OS Virtualizes the Hardware

Device Drivers

HARDWARE

CPU Virtualization (x86)

Clustering and Failover• Node 1 and Node 2 have same

content either through shared or replicated mode.

• One node is active and the rest is passive.

• Heartbeat keeps track of the presence of the node

• Node 1 goes down, no heartbeat• The services are transferred and

rendered from Node 2• This is transparent and hence

virtual to the client

Java Virtual Machine• Class loader loads the java

classes/interfaces• Execution Engine executes

the methods contained in the loaded classes

• Run time data areas store run time data like stack.

• Each class execution is done by means of a java thread.

Virtualization Wikipedia Definition

Virtualization, in computing, refers to the act of creating a virtual (rather than actual) version of something, including but not limited to a virtual computer hardware platform, operating system (OS), storage device, or computer network resources.

Concept Of Virtualization

• Simulated Environment (a Virtual Machine) provides the environment required to run he Guest Software

• The Guest Software can be complete OS to specific programs• Simulated Environment can control the guest environment in terms of

access and lifetime• The Guest Program thinks that it is running in an actual system not a

simulated environment

Actual System

SimulatedEnv

GUEST Software

SimulatedEnv

GUEST SoftwareSimulated

Env

Basic Architecture

• Hypervisor allows multiple Guest OSs share the Hardware via Host OS.

• Mostly the Hypervisor is run inside the HOST OS• Example : Guest Windows 7 Prof SP1 running on a HOST

Ubuntu 13.1• In some cases, the Hypervisor is inside the Host OS itself

Hypervisor (Virtual Machine Monitor)

• Directly runs on the hardware of the host

• Shares the hardware resources with multiple VMs

• Manages CPU, memory and Network interface between different VMs

• Runs at ring 0

Virtual Machine

• Software implementation of a computing environment

• A computing environment is a software process which can host an OS or a program

• Computing Environment emulates – A processor architecture– Memory – Secondary Storage

TYPES OF VIRTUALIZATION

CPU Virtualization

• CPU is shared between multiple Guest OSs

• Hypervisor does the translations of commands between Guest OSs and the CPU

• Guest OS cannot reside on Ring 0 makes the more complex

Full Virtualization

• Guest OS in Ring 1, Hypervisor in Ring 0

• Hypervisor traps the Guest OS Privileged commands and does the binary translation of the command.

• No change in Guest OS required• Reduced performance due to this

translation process (Virtualization overhead)

Full Virtualization WithReducing Virtualization Overhead

• Guest OS runs on Ring 0 (which is an improvement)

• Ring -1 introduced which runs the Hypervisor

• No binary translation is required as Guest OS can run Privileged instructions directly on the H/W.

• For I/O calls, Hypervisor is used.• Improves performance • Needs change in CPU Arch

(provided by intel-VT and AMD-V)

Para Virtualization• A software hypervisor is installed

on a Physical server• The guest OS is modified to

make Hypervisor calls• These Hypervisor calls (CPU and

memory access) are directly send to the hardware

• I/O calls are routed through regular Hypervisor

• The Hypervisor is not overloaded

• Overhead in modifying OS Kernel

Network Virtualization

To Summarize….

Benefits of Virtualization

• Server Consolidation• Testing and Development• Dynamic Load Balancing • Disaster Recovery• Pre-loaded VMs for specific needs • Virtual Desktops• Reduces installation and configuration time of the

data center• Improves data center efficiency

Virtualization and the Cloud

• Cloud computing requires many many servers to carry out varied activities

• Creating phyiscal servers is expensive and not scalable• Hence, virtualization is a natural fit • Scalability is a major use case in Cloud computing, it is

easy to create/clone VMs and increase capacities• If there are node failures, it is easy to bring up a VM

from nowhere• Maintaining a VM is easier than maintaining a physical

box.

Thank You