Download UNIT – II – Virtualization

Cloud Computing – UNIT - II
VIRTUALIZATION
Virtualization
• Hiding the reality
• The mantra of smart computing is to
intelligently hide the reality
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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
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
Actual
System
Simulated
Env
Simulated
Env
Simulated
Env
GUEST
Software
GUEST
Software
• 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
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 With
Reducing 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 AMDV)
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
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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