Unit-2

Virtualization
Intro.Cloud Computing(CC)
202046710
Prof.Mahek Gohil
GCET IT
✓ Outline
✔ Introduction to Virtualization

 Characteristics of Virtualized Environment

 Taxonomy of Virtualization Techniques

 Virtualization and Cloud Computing

 Pros and Cons of Virtualization

 Technology Examples

 Implementation Levels of Virtualization

 Virtualization Structures/Tools and Mechanisms

 Types of Hypervisors

 Virtualization of CPU, Memory, and I/O Devices, Virtual Clusters and Resource Management
Why we need virtualization?

 Each physical hardware for each server

 High Cost
 Power consumption
 Down Time of a server
 Machine Crashing
 High Infrastructure
 Less Utilization of resource
The Traditional Server

Web Server App Server DB Server Email

Windows Linux Linux Windows
IIS Glassfish MySQL Exchange
And if something goes wrong ...

Web Server App Server DB Server Email

Windows Linux Linux Windows
IIS Glassfish MySQL Exchange
The Traditional Server
 System Administrators often talk about servers as a whole unit that includes the hardware, the
OS, the storage, and the applications.

 Servers are often referred to by their function i.e. the Exchange server, the SQL server, the
File server, etc.

 If the File server fills up, or the Exchange server becomes overtaxed, then the System
Administrators must add in a new server.

 Unless there are multiple servers, if a service experiences a hardware failure, then the service
is down.

 System Admins can implement clusters of servers to make them more fault tolerant. However,
even clusters have limits on their scalability, and not all applications work in a clustered
environment.
The Traditional Server
 Pros
 Easy to conceptualize
 Fairly easy to deploy
 Easy to backup
 Virtually any application/service can be run from this type of setup

 Cons
 Expensive to acquire and maintain hardware
 Not very scalable
 Difficult to replicate
 Redundancy is difficult to implement
 Vulnerable to hardware outages
 In many cases, processor is under-utilized
Introduction to Virtualization
 Virtualization is a technique to divide the computer resources logically. It’s achieved by
abstracting away the underlying complexity of resource segregation.
 Virtualization is a technique how to separate a service from the underlying physical delivery of
that service. It is the process of creating a virtual version of something like computer
hardware.
 Virtualization helps us to create software-based or virtual versions of a computer resource.
These computer resources can include computing devices, storage, networks, servers, or even
applications
 In other words, one of the main cost-effective, hardware-reducing, and energy-saving
techniques used by cloud providers is Virtualization. Virtualization allows sharing of a single
physical instance of a resource or an application among multiple customers and organizations
at one time.
Introduction to Virtualization

The virtualization reference model.

Working of Virtualization
 Hypervisor software facilitates virtualization. A hypervisor sits on top of an operating system
but we can also have hypervisors that are installed directly onto the hardware. Hypervisors
take physical resources and divide them up so that virtual environments can use them.
 The machine on which the virtual machine is going to create is known as Host Machine and that
virtual machine is referred as a Guest Machine
Virtualization
 Pros
 Resource pooling
 Highly redundant
 Highly available
 Rapidly deploy new servers
 Easy to deploy
 Reconfigurable while services are running
 Optimizes physical resources by doing more
with less

 Cons
 Slightly harder to conceptualize
Characteristics of virtualization environments
Characteristics of virtualized environments
1. Increased Security: The ability to control the execution of a guest program in a
completely transparent manner opens new possibilities for delivering a secure, controlled
execution environment. All the operations of the guest programs are generally performed
against the virtual machine, which then translates and applies them to the host programs
2. Managed Execution: In particular, sharing, aggregation, emulation, and isolation are the
most relevant features.
3. Sharing: Virtualization allows the creation of a separate computing environment within the
same host.
4. Aggregation: It is possible to share physical resources among several guests, but
virtualization also allows aggregation, which is the opposite process.
5. Portability: The concept of portability applies in different ways according to the specific
type of virtualization considered. In the case of a hardware virtualization solution, the guest is
packaged into a virtual image that, in most cases, can be safely moved and executed on top of
different virtual machines.
Characteristics of virtualized environments

Functions enabled by managed execution

Taxonomy of Virtualization Techniques

 Execution virtualization:
 Execution virtualization includes all techniques that aim to emulate an execution
environment that is separate from the one hosting the virtualization layer.
 All these techniques concentrate their interest on providing support for the execution of
programs, whether these are the operating system, a binary specification of a program
compiled against an abstract machine model, or an application.
 Therefore, execution virtualization can be implemented directly on top of the hardware by
the operating system, an application, or libraries dynamically or statically linked to an
application image
Taxonomy of Virtualization Techniques

A taxonomy of virtualization techniques.

Taxonomy of Virtualization Techniques

 All the current systems support at least two different execution modes: supervisor mode
and user mode. The first mode denotes an execution mode in which all the instructions
(privileged and non-privileged) can be executed without any restriction.
 This mode, also called master mode or kernel mode, is generally used by the operating
system (or the hypervisor) to perform sensitive operations on hardware level resources.
Taxonomy of Virtualization Techniques

 In user mode, there are restrictions to control the machine-level resources. If code running in
user mode invokes the privileged instructions, hardware interrupts occur and trap the
potentially harmful execution of the instruction.
 Despite this, there might be some instructions that can be invoked as privileged instructions
under some conditions and as non-privileged instructions under other conditions.
 The distinction between user and supervisor mode allows us to understand the role of the
hypervisor and why it is called that. Conceptually, the hypervisor runs above the supervisor
mode, and from here the prefix hyper- is used.
 In reality, hypervisors are run in supervisor mode, and the division between privileged and
non-privileged instructions has posed challenges in designing virtual machine managers. It is
expected that all the sensitive instructions will be executed in privileged mode, which
requires supervisor mode in order to avoid traps.
Types of Virtualization
 Hardware-level virtualization:
Hardware-level virtualization, also known as
system virtualization, is a technique that allows
multiple operating systems to run concurrently
on a single physical machine by creating virtual
machines (VMs) that mimic the underlying
hardware.
 https://youtu.be/tPBcmgtNmv0?si=0CYNoQU-
dPAwCtGh
Types of Virtualization
Types of Virtualization
 Hardware Virtualization:
 Hardware-level virtualization is a virtualization technique that provides an abstract execution
environment in terms of computer hardware on top of which a guest operating system can be
run.
 In this model, the guest is represented by the operating system, the host by the physical
computer hardware, the virtual machine by its emulation, and the virtual machine manager
by the hypervisor. The hypervisor is generally a program or a combination of software and
hardware that allows the abstraction of the underlying physical hardware
 Hardware-level virtualization is also called system virtualization, since it provides ISA to
virtual machines, which is the representation of the hardware interface of a system. This is to
differentiate it from process virtual machines, which expose ABI to virtual machines.
Types of Hardware Virtualization
Types of Hardware Virtualization
VMware Workstation VMware ESXi QEMU
Type: Desktop hypervisor (Type 2) Type: Bare-metal hypervisor (Type Type: Emulator and virtualizer.
1)

Installation: Installed on top of an Installation: Installs directly on the Purpose: Emulates different CPU
existing operating system hardware, replacing the host OS architectures and can also be used
for virtualization when combined
with KVM (Kernel-based Virtual
Machine) on Linux.

Use Cases: Development and Use Cases: Production Use Cases: Cross-platform software
testing, running multiple operating environments, data centers, remote development, testing on different
systems on one machine, learning offices, disaster recovery architectures, and Android
server management, product emulation.
demos, staging for vSphere
Taxonomy of Virtualization Techniques

A taxonomy of virtualization techniques.

Operating system-level virtualization

 Operating System-Level Virtualization, also known as containerization, is a lightweight

virtualization approach that enables multiple isolated user-space instances (containers) to
run on a single host OS kernel. Each container shares the host system's kernel but operates as
if it were an independent OS.
 Examples of operating system-level virtualizations are FreeBSD Jails, IBM Logical Partition
(LPAR), SolarisZones and Containers, Parallels Virtuozzo Containers, OpenVZ, iCore Virtual
Accounts, Free Virtual Private Server (FreeVPS), and others.
 The services offered by these technologies differ, and most of them are available on Unix-
based systems. Some of them, such as Solaris and OpenVZ, allow for different versions of the
same operating system to operate concurrently.
Operating system-level virtualization Characteristics

 Lightweight:
 Containers are more lightweight compared to traditional VMs because they share the host OS
kernel.
 Reduced overhead in terms of CPU and memory usage

 Isolation:
 Containers provide process and file system isolation using namespaces.
 Each container has its own isolated user space, network interfaces, and process tree.

 Efficiency:
 Containers start and stop much faster than VMs.

 Better resource utilization as they share the OS kernel and libraries.

Operating system-level virtualization Characteristics

 Portability:
 Containers package applications with all their dependencies, making them portable across
different environments.

 Security:
 While containers provide isolation, they share the host OS kernel, which may pose security
risks.
 Additional security mechanisms (e.g., SELinux, AppArmor) are often used to enhance container
security.
Technologies
1. Kubernetes 2.LXC (Linux Containers) 3.Podman 4.rkt (Rocket) 5.Docker

 Docker: Provides tools to create, deploy, and manage containers.

Development Testing Deployment Maintaince

Programming Language-Level Virtualization

 Programming Language-Level Virtualization involves creating a virtual environment for

executing code that abstracts the underlying hardware and operating system. This type of
virtualization is primarily concerned with running code written in a specific programming
language within a managed runtime environment, which can provide various services such as
garbage collection, exception handling, and dynamic typing.
Technologies and Examples

1. Java Virtual Machine (JVM)

2. Common Language Runtime (CLR) Supports multiple languages (C#, VB.NET, F#)
3. Python Interpreter
4. JavaScript Engines
5. PHP Zend Engine
6. Ruby MRI (Matz's Ruby Interpreter)
Application-level virtualization

 Application-level virtualization is a technique allowing applications to be run in runtime

environments that do not natively support all the features required by such applications. In
this scenario, applications are not installed in the expected runtime environment but are run
as though they were.

 Examples:
1. Vmware ThinApp 2. App-V 3. Turbo 4. BoxedApp 5. Microsoft App-V (Application
Virtualization)etc
Storage Virtualization
 Storage virtualization is an array of servers that are managed by a virtual storage system. The
servers aren’t aware of exactly where their data is stored and instead function more like worker
bees in a hive. It makes managing storage from multiple sources be managed and utilized as a
single repository. storage virtualization software maintains smooth operations, consistent
performance, and a continuous suite of advanced functions despite changes, breaks down, and
differences in the underlying equipment.
Types of Storage Virtualization
Storage Virtualization
 SAN (Storage Area Network): A network of storage devices that provides block-level storage to servers.
 NAS (Network Attached Storage): A storage device connected to a network that provides file-level
storage to clients.
 Software-Defined Storage (SDS): Abstracts storage resources using software, separating the storage
hardware from the management software.
 Examples: VMware vSAN, Ceph, and Microsoft Storage Spaces Direct
Network Virtualization
 The ability to run multiple virtual networks with each having a separate control and data plan.
It co-exists together on top of one physical network. It can be managed by individual parties
that are potentially confidential to each other. Network virtualization provides a facility to
create and provision virtual networks, logical switches, routers, firewalls, load balancers,
Virtual Private Networks (VPN), and workload security within days or even weeks.
Desktop virtualization

 This is the kind of virtualization in which the data is collected from various sources and
managed at a single place without knowing more about the technical information like how data
is collected, stored & formatted then arranged that data logically so that its virtual view can
be accessed by its interested people and stakeholders, and users through the various cloud
services remotely.
 Many big giant companies are providing their services like Oracle, IBM, At scale, Cdata, etc.
 Virtual desktop infrastructure (VDI)
 Remote desktop services(RDS)
 Desktop-as-a-Service (DaaS)
Types of Desktop virtualization
Types of Desktop virtualization

https://blog.temok.com/desktop-virtualization/
Software Virtualization
 Software virtualization is just like a virtualization but able to abstract the software
installation procedure and create virtual software installations.
 Virtualized software is an application that will be "installed" into its own self-contained unit.
 Example of software virtualization is VMware software, virtual box etc.
What is a hypervisor?
What is a hypervisor?

 A hypervisor is a software that you can use to run multiple virtual machines on a single physical
machine. Every virtual machine has its own operating system and applications.
 The hypervisor allocates the underlying physical computing resources such as CPU and memory
to individual virtual machines as required. Thus, it supports the optimal use of physical IT
infrastructure.
 It recreates a hardware environment in which guest operating systems are installed. There are
two major types of hypervisor: Type I and Type II
Why is a hypervisor important?

 Hypervisors are the underlying technology behind virtualization or the decoupling of

hardware from software. IT administrators can create multiple virtual machines on a single
host machine. Each virtual machine has its own operating system and hardware resources
such as a CPU, a graphics accelerator, and storage. You can install software applications on a
virtual machine, just like you do on a physical computer.
 The fundamentals of virtual machines and other virtualization technologies have enabled cloud
computing services in enterprise applications. They allow you to scale computing services
efficiently on limited hardware infrastructure.
 For example, different business departments can run different workloads separately by
using multiple virtual machines on a single server.
How does a hypervisor work?

 System administrators install the hypervisor software on physical servers.

 The hypervisor loads the virtual machine images to create multiple virtual operating
systems.
 The physical machine is known as a host, and the virtual operating systems are guests.
 The hypervisor relays requests for processing power, memory, storage, and other resources
to the host machine in several ways, including API calls.
What are the types of hypervisors?

 There are two types of hypervisors, each differing in architecture and performance.
1. Type 1 hypervisor
2. Type 2 hypervisor
Type 1 hypervisor
 The type 1 hypervisor sits on top of the metal server and has direct access to the hardware
resources.
 The type 1 hypervisor is also known as a bare-metal hypervisor.
 The host machine does not have an operating system installed in a bare-metal hypervisor
setup. Instead, the hypervisor software acts as a lightweight operating system.
 The type 1 hypervisor is very efficient.
 It can directly manage and allocate resources for multiple virtual machines without going
through the host operating system.
 These types of hypervisors are also more secure, as the absence of a host operating system
reduces the risks of instability.
List of type 1 hypervisors

1.Proxmox VE
 Proxmox VE (PVE), short for Proxmox Virtual Environment, is an open source
virtualization platform based on Debian. It supports both container-based virtualization
with LXC and full virtualization with KVM.
 Developer: Proxmox Server Solutions.
 License: GNU AGPL v3.
 Latest version: Proxmox 8.1.
List of type 1 hypervisors

2.KVM
 KVM, short for Kernel-based Virtual Machine, is a virtualization module within the
Linux kernel allowing it to work as a bare-metal hypervisor.
 KVM was developed by Avi Kivity at Qumranet (a tech startup company that would be
acquired by Red Hat in 2008) in mid-2006 and it was merged into the mainline Linux
kernel in 2007 (version 2.6.20).
 Developer: The Linux Kernel community.
 License: GNU GPL or LGPL.
List of type 1 hypervisors

3.LXC
 LXC, short for Linux Containers, is an open source OS-level virtualization platform
designed for developing Linux container technologies.
 Developer: Virtuozzo, IBM, Google, Eric Biederman and others (kernel); Daniel Lezcano,
Serge Hallyn, Stéphane Graber and others (userspace).
 License: GNU LGPLv2.1+.
 Latest version: LXC 5.0.
List of type 1 hypervisors

4.VMware ESXi
 VMware ESXi or VMware ESXi Hypervisor, formerly VMware ESX, is an enterprise-
class, bare-metal hypervisor part of VMware’s vSphere virtualization suite. It includes
its own kernel and other vital OS components. It was renamed from VMware ESX to
VMware ESXi in version 4.1 in 2010.
 Developer: VMware, acquired by Broadcom in November 2023.
 License: proprietary.
 Latest version: VMware ESXi 8.0 Update 2.
List of type 1 hypervisors

5.OpenStack
 OpenStack is an open source cloud platform, deployed both in public and private cloud.
It was first developed by Rackspace Hosting and NASA in 2010.
 Developer: Open Infrastructure Foundation and community.
 License: Apache License 2.0.
 Latest version: OpenStack Bobcat, 2023.2.
List of type 1 hypervisors

6.Red Hat Virtualization (RHV)

 RHV, short for Red Hat Virtualization, is an enterprise virtualization platform based on
KVM and Red Hat Enterprise Linux. It was formerly known as Red Hat Enterprise
Virtualization.
 Developer: Red Hat.
 Latest version: RHV 4.4.
List of type 1 hypervisors
7.Hyper-V
 Hyper-V or Microsoft Hyper-V is a bare-metal hypervisor, developed by Microsoft.
 Developer: Microsoft.
8.XEN
 XEN or XEN Project is a bare-metal hypervisor originally developed by the University of
Cambridge’s Department of Computer Science and Technology (former Computer
Laboratory), led by the senior lecturer Ian Pratt and his PhD student Keir Fraser, in
2003. XEN is currently developed and maintained by the Linux Foundation with support
from companies such as Intel, Citrix and AMD.
 Developer: Linux Foundation with support from some companies.
 License: GNU GPL.
 Latest version: Xen 4.18.
Type 2 hypervisor
 The type 2 hypervisor is a hypervisor program installed on a host operating system. It is also
known as a hosted or embedded hypervisor. Like other software applications, hosted
hypervisors do not have complete control of the computer resources. Instead, the system
administrator allocates the resources for the hosted hypervisor, which it distributes to the
virtual machines.
 The hypervisor and its hosted virtual machines are dependent on the stability of the host
operating system.
 When the virtual machine requests computing resources, the hypervisor cannot directly access
the underlying hardware but relays the request to the host operating system.
List of type 2 hypervisors
1.VirtualBox
 VirtualBox or Oracle VM VirtualBox, formerly known as Innotek VirtualBox, Sun
VirtualBox and Sun xVM VirtualBox, is a free, open source hosted hypervisor.
 It was originally created by Innotek, which was later acquired by Sun Microsystems in
2008 (acquired by Oracle in 2010).
 Developer: Oracle Corporation.
 License: GPLv2 and proprietary license.
 Latest version: VirtualBox 7.0.1
List of type 2 hypervisors
2.QEMU
 QEMU is a free, open source hosted hypervisor, originally written by Fabrice Bellard
and licensed under the GNU General Public License. It is currently developed and
maintained by the QEMU team. QEMU can be used as a machine emulator and as a
virtualizer.
 Developer: QEMU team: Peter Maydell and others.
 License: GPLv2 and other licenses.
 Latest version: QEMU 8.2.2.
List of type 2 hypervisors
3. VMware Workstation Player
 VMware Workstation Player, formerly VMware Player, is a hosted hypervisor for
running virtual machines on Microsoft Windows or Linux PC. VMware Player and
VMware Workstation were combined within a single package in 2015. It has a free
version for non-commercial, personal use and a commercial license for commercial
organizations.
 Developer: VMware, acquired by Broadcom in November 2023.
 License: proprietary.
 Latest version: VMware Workstation 17.0 Player.
 Instruction Set Architecture
Application binary interface

Hosted (left) and native (right) virtual machines. This figure provides a graphical
representation of the two types of hypervisors
A hypervisor reference architecture.
What is a cloud hypervisor?
 Cloud providers usually use bare-metal hypervisors to allocate virtualized hardware
resources to users.
 For example, Amazon Elastic Compute Cloud (Amazon EC2) allows organizations to scale their
cloud computing capacities with Xen-based hypervisors.
 It provides a cost-effective cloud solution where businesses only pay for the compute resources
needed to run their AWS workload.
Types of Hardware Virtualization
Technology examples
 Xen: paravirtualization:
 Xen is an open-source initiative implementing a virtualization platform based on
paravirtualization. Initially developed by a group of researchers at the University of Cambridge
in the United Kingdom.
 Xen-based technology is used for either desktop virtualization or server virtualization, and
recently it has also been used to provide cloud computing solutions by means of Xen Cloud
Platform (XCP).
 Recently Xen has been advanced to support full virtualization using hardware-assisted
virtualization.
Technology examples
 Xen: paravirtualization:

Xen architecture and guest OS management.

Binary Translation with Full Virtualization
 Depending on implementation technologies, hardware virtualization can be classified into two
categories: full virtualization and host-based virtualization.
 Full virtualization does not need to modify the host OS. It relies on binary translation to trap
and to virtualize the execution of certain sensitive, non-virtualizable instructions. The guest
OSes and their applications consist of non-critical and critical instructions. In a host-based
system, both a host OS and a guest OS are used. A virtualization software layer is built between
the host OS and guest OS. These two classes of VM architecture are introduced next.
1. Full Virtualization
2. Binary Translation of Guest OS Requests Using a VMM
Full Virtualization

A full virtualization reference model.

1.Full Virtualization
 With full virtualization, noncritical instructions run on the hardware directly while critical
instructions are discovered and replaced with traps into the VMM to be emulated by software.
 Both the hypervisor and VMM approaches are considered full virtualization.
 Why are only critical instructions trapped into the VMM?
 This is because binary translation can incur a large performance overhead. Noncritical
instructions do not control hardware or threaten the security of the system, but critical
instructions do.
 Therefore, running noncritical instructions on hardware not only can promote efficiency, but
also can ensure system security.
2.Binary Translation of Guest OS Requests Using a VMM
Binary Translation of Guest OS Requests Using a VMM
 This approach was implemented by VMware and many other software companies. As shown in
Figure , VMware puts the VMM at Ring 0 and the guest OS at Ring 1. The VMM scans the
instruction stream and identifies the privileged, control- and behavior-sensitive instructions.
When these instructions are identified, they are trapped into the VMM, which emulates the
behavior of these instructions. The method used in this emulation is called binary translation.
 Therefore, full virtualization combines binary translation and direct execution. The guest OS is
completely decoupled from the underlying hardware. Consequently, the guest OS is unaware
that it is being virtualized.
 The performance of full virtualization may not be ideal, because it involves binary translation
which is rather time-consuming.
KVM (Kernel-Based VM)
 Kernel-based Virtual Machine (KVM) is an open source virtualization technology built into
Linux®. Specifically, KVM lets you turn Linux into a hypervisor that allows a host machine to
run multiple, isolated virtual environments called guests or virtual machines (VMs).
How does KVM work?

 KVM converts Linux into a type-1 (bare-metal) hypervisor.

 All hypervisors need some operating system-level components—such as a memory manager,
process scheduler, input/output (I/O) stack, device drivers, security manager, a network stack,
and more—to run VMs. KVM has all these components because it’s part of the Linux kernel.
 Every VM is implemented as a regular Linux process, scheduled by the standard Linux scheduler,
with dedicated virtual hardware like a network card, graphics adapter, CPU(s), memory, and
disks.
KVM features

 Security: KVM uses a combination of security-enhanced Linux (SELinux) and secure

virtualization (sVirt) for enhanced VM security and isolation.

 Storage: KVM is able to use any storage supported by Linux, including some local disks
and network-attached storage (NAS). Multipath I/O may be used to improve storage and provide
redundancy. KVM also supports shared file systems so VM images may be shared by multiple
hosts.

 Hardware support: KVM can use a wide variety of certified Linux-supported hardware
platforms.

 Memory management: KVM inherits the memory management features of Linux, including
non-uniform memory access and kernel same-page merging. The memory of a VM can be
swapped, backed by large volumes for better performance, and shared or backed by a disk file.
KVM features

 Live migration: KVM supports live migration, which is the ability to move a running VM
between physical hosts with no service interruption.

 Performance and scalability: KVM inherits the performance of Linux, scaling to match
demand load if the number of guest machines and requests increases.

 Scheduling and resource control: In the KVM model, a VM is a Linux process, scheduled
and managed by the kernel. The Linux scheduler allows fine-grained control of the resources
allocated to a Linux process and guarantees a quality of service for a particular process.

 Lower latency and higher prioritization: The Linux kernel features real-time
extensions that allow VM-based apps to run at lower latency with better prioritization
(compared to bare metal)., and shared or backed by a disk file.
Review questions
1.What is virtualization and what are its benefits?
2. What are the characteristics of virtualized environments?
3. Discuss classification or taxonomy of virtualization at different levels.
4. Discuss the machine reference model of execution virtualization.
5. What are hardware virtualization techniques?
6. List and discuss different types of virtualization.
7. What are the benefits of virtualization in the context of cloud computing?
8. What are the disadvantages of virtualization?
9. What is Xen? Discuss its elements for virtualization.
10. Discuss the reference model of full virtualization.
11. Discuss the architecture of Hyper-V. Discuss its use in cloud computing