Unit 3

Virtualization – Basics, Cloud vs Virtualization, Types of virtualization,

Hypervisor types; Containers – Introduction to dockers and containers,
containerization vs virtualization, docker architecture, Use cases, Learn how to
build container images, Operations on container images; Kubernetes – Need for
orchestration, container orchestration methods, Introduction to Kubernetes,
Kubernetes architecture, using YAML file, Running Kubernetes via minikube.
 Introduction
• Virtualization is an enabling technology for the different cloud computing services.

• Virtualization is a technology that enables the single physical infrastructure to function as a multiple
logical infrastructure or resources.

• Virtualization is not only limited to the hardware, it can take many forms such as memory, processor,
I/O, network, OS, data, and application.

• Before virtualization, the single physical infrastructure was used to run a single OS and its applications,
which results in underutilization of resources. The nonshared nature of the hardware forces the
organizations to buy a new hardware to meet their additional computing needs.

• After virtualization was introduced, different OSs and applications were able to share a single physical
infrastructure.
Before Virtualization
After Virtualization
 What is Virtualization ?
• Virtualization is originated in the1960s at IBM.
• Virtualization is the "creation of a virtual (rather than
actual) version of something, such as a server, a
desktop, a storage device, an operating system or
network resources".
• In other words, Virtualization is a technique, which
allows to share a single physical instance of a resource
or an application among multiple customers and
organizations.

• Virtualization allows concurrent execution of multiple OSs

(and their applications) on the same physical machine.
 Virtualization….
• Virtualization creates a virtual layer using the
hypervisor software, which manages resources assigned
to the virtual instances. The newly formed virtual
representation is known as virtual machines (VMs).

• Virtual resources = each OS thinks that it “owns”

hardware resources

• Virtualization layer =management of physical

hardware (virtual machine monitor, hypervisor)
VMM Goals: Fidelity
• Virtual machine (VM) = OS+ applications + virtual
Performance
resources (guest domain).
Safety & isolation
Virtual machines and hypervisors are two important concepts in virtualization.

• Virtual machine: A virtual machine is a software-defined computer that runs on a physical

computer with a separate operating system and computing resources (VM is an emulation or
a virtual presentation of a physical system). The physical computer is called the host
machine and virtual machines are guest machines. Multiple virtual machines can run on a
single physical machine. Virtual machines are abstracted from the computer hardware by a
hypervisor.

• Hypervisor: The hypervisor is a software component that manages multiple virtual

machines in a computer. It ensures that each virtual machine gets the allocated resources and
does not interfere with the operation of other virtual machines.
 Virtualization Vs Cloud
Virtualization Cloud
Definition Technology Methodology
Create multiple simulated environments from 1 Pool and automate virtual resources for
Purpose
physical hardware system on-demand use
Deliver packaged resources to specific users for Deliver variable resources to groups of
Use
a specific purpose users for a variety of purposes
Configuration Image-based Template-based
Lifespan Years (long-term) Hours to months (short-term)
High capital expenditures (CAPEX), low Private cloud: High CAPEX, low OPEX
Cost
operating expenses (OPEX) Public cloud: Low CAPEX, high OPEX
Scalability Scale up Scale out
Workload Stateful Stateless
Tenancy Single tenant Multiple tenants
 Advantages and Disadvantages of Virtualization
• Industries adopt virtualization in their organization because of the following benefits:
• Better resource utilization
• Increases ROI (return on investment )
• Dynamic data center
• Supports green IT
• Eases administration
• Improves disaster recovery

• While virtualization offers many benefits, it also has some drawbacks:

• Single point of failure
• Demands high-end and powerful infrastructure
• May lead to lower performance
• Requires specialized skill set
 Benefits of Virtualization
• Consolidation: It is this ability to run multiple virtual machines, with their operating systems
and applications on a single physical platform.

- Decrease cost, improve manageability (with fewer admins and with fewer electrical bills)

• Migration: Migrate the OS in the applications from one physical machine to another physical
machine.

- Greater availability of the services, improve reliability

• Security: As the OS and the applications are nicely encapsulated in a virtual machine. It
becomes more easy to contain any kinds of bugs, or any kinds of malicious behavior, to those
resources that are available to the virtual machine only, and not to potentially affect the entire
hardware system.

• Some other benefits: Debugging, Provide affordable Support for legacy OSs
Vu Pham
 Virtualization example
Consider a company that needs servers for three functions:

1. Store business email securely

2. Run a customer-facing application

3. Run internal business applications

Each of these functions has different configuration requirements:

• The email application requires more storage capacity and a Windows operating system.

• The customer-facing application requires a Linux operating system and high processing power to
handle large volumes of website traffic.

• The internal business application requires iOS and more internal memory (RAM).
• To meet these requirements, the company sets up three different dedicated physical servers for each
application. The company must make a high initial investment and perform ongoing maintenance and
upgrades for one machine at a time. The company also cannot optimize its computing capacity. It pays 100%
of the servers’ maintenance costs but uses only a fraction of their storage and processing capacities.

• Efficient hardware use: With virtualization, the company creates three digital servers, or virtual machines,
on a single physical server. It specifies the operating system requirements for the virtual machines and can
use them like the physical servers. However, the company now has less hardware and fewer related
expenses.

• Infrastructure as a service: The company can go one step further and use a cloud instance or virtual
machine from a cloud computing provider such as AWS. AWS manages all the underlying hardware, and the
company can request server resources with varying configurations. All the applications run on these virtual
servers without the users noticing any difference. Server management also becomes easier for the company’s
IT team.
 Hypervisors
• Before hypervisors are introduced, there was a one-to-one relationship between hardware and
OSs.

- This type of computing results in underutilized resources.

• After the hypervisors are introduced, it became a one-to-many relationship. With the help of
hypervisors, many OSs can run and share a single hardware.

• The virtual environment can be created with the help of a software tool called hypervisors.

• Hypervisors are the software tool that sits in between VMs and physical infrastructure and
provides the required virtual infrastructure for VMs.

• Generally, the virtual infrastructure means virtual CPUs (vCPUs), virtual memory, virtual NICs
(vNICs), virtual storage, and virtual I/O devices.
• The hypervisors are also called VMM(Virtual Machine Monitors).

• They are the key drivers in enabling virtualization in cloud data centers.

• There are different hypervisors that are being used in the IT industry.

• Some of the examples are VMware, Xen, Hyper-V, KVM, and OpenVZ.
 Types of Hypervisors

Hypervisors are generally classified into two categories:

1. Bare-metal hypervisor
or Native Hypervisor (Type 1)

2. Hosted Hypervisor (Type 2)

 Bare-metal hypervisor(Type 1)
• Type 1 hypervisor is also known as bare metal or native hypervisor.

• It can run and access physical resources directly without the help of any host OS.

• Here, the additional overhead of communicating with the host OS is reduced and offers
better efficiency when compared to type 2 hypervisors.

• This type of hypervisors is used for servers that handle heavy load and require more
security.

• Some examples of type 1 hypervisors include Microsoft Hyper-V, Citrix XenServer,

VMWare ESXi, and Oracle VM Server for SPARC.
 Bare-metal virtualization model
Bare-metal hypervisor (Type 1)

VMM (hypervisor) manages all

hardware resources and supports
execution of entire VMs.

Privileged, service VM to deal with

devices (and other configuration
and management task)

Cloud Computing and Distributed Systems Vu Pham Virtualization

 Hosted Hypervisor(Type 2)
• Type 2 hypervisors are also known as embedded or hosted hypervisors.
• This type of hypervisors requires the host OS and does not have direct access to the physical
hardware.
• These types of hypervisors are installed on the host OS as a software program.
• The host OS is also known as physical host, which has the direct access to the underlying
hardware.
• The major disadvantage of this approach is if the host OS fails or crashes, it also results in
crashing of VMs.
• So, it is recommended to use type 2 hypervisors only on client systems where efficiency is
less critical.
• Examples of type 2 hypervisors include VMWare Workstation and Oracle Virtualbox.
 Hosted Hypervisor
Hosted Hypervisor (Type 2)

In this model, at the lowest level,

there is a full fledged host OS that
manages all of the hardware
resources.

The Host OS integrates a VMM

module, that's responsible for
providing the virtual machines with
their virtual platform interface and
for managing all of the context
switching scheduling, etc.

Cloud Computing and Distributed Systems Vu Pham Virtualization

Hypervisors in the market
 Bare-metal Hypervisors
• This model is adapted by the Xen virtualization solution
(open source or Citrix Xen Server) and also by the
VMware's hypervisor, the ESX hypervisor.
(i) Xen (Open source or Citrix Xen Server)
- The VMs that are run in the virtualized environment
are referred to as domains.
- The privileged domain is called dom 0, and the guest
VMs are referred to as domUs.
- Xen is the actual hypervisor and all of the drivers are
running in the privileged domain, in dom 0.
(ii) ESX (VMware)
-Given that VMware and its hypervisors were first to market, VMware still owns the largest
percentage of virtualized server cores. So these server cores run the ESX hypervisor and also
provide the drivers for the different devices. That are going to be part of the hypervisor. To
support a third party community of developers VMware exports a number of APIs.

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 Hosted Hypervisor

Example:
• KVM (Kernel-based VM) Based on
Linux
• KVM kernel module + hardware
emulator called QEMU for hardware
virtualization

• Leverages large Linux open-source

community
 Protection Rings
• Protection rings are used to isolate the OS from
untrusted user applications. The OS can be protected
with different privilege levels.
• In protection ring architecture, the rings are arranged
in hierarchical order from ring 0 to ring 3.
• Ring 0 contains the programs that are most privileged,
and ring 3 contains the programs that are least
privileged.
• Normally, the highly trusted OS instructions will run
in ring 0, and it has unrestricted access to physical
resources.
• Ring 3 contains the untrusted user applications, and it
has restricted access to physical resources.
• The other two rings (ring 1 and ring 2) are allotted for
device drivers.
• This protection ring architecture restricts
the misuse of resources and malicious
behaviour of untrusted user-level
programs.
• For example, any user application from
ring 3 cannot directly access any physical
resources as it is the least privileged level.
• But the kernel of the OS at ring 0 can
directly access the physical resources as it
is the most privileged level.
 Types of Virtualization
The different types of virtualization are:

1) Desktop Virtualization

2) Network Virtualization
3) Storage Virtualization

4) Application Virtualization
 Server Virtualization

• Server Virtualization is the process of dividing a physical

server into several virtual servers, called virtual private
servers. Each virtual private server can run
independently.
• The concept of Server Virtualization widely used in
the IT infrastructure to minimizes the costs by
increasing the utilization of existing resources.
 Desktop Virtualization
• In this type of virtualization, we can run multiple operating
systems, each in its own virtual machine on the same system.

• Types of desktop virtualization:

1. Virtual desktop infrastructure (VDI) runs numerous virtual
machines on a central server and then hosts it to the host system
according to the user's requirements. In this way, we can access
any operating system from any device without installing the
actual operating system in their local machine.

2. Local desktop virtualization is the type that runs the hypervisor

on the local system, which allows the user to install multiple
operating systems simultaneously without affecting the host's
operating system.
 Network Virtualization
• This type of virtualization can combine multiple physical networks
into one virtual, software-based network, or it can divide one
physical network into separate, independent virtual networks.

• Types of network virtualization:

1. Software-defined networking (SDN) virtualizes hardware that

controls network traffic routing.

2. Network function virtualization (NFV) virtualizes hardware

appliances that provide network-specific functions easier to
configure and manage, e.g., firewall, etc.
 Storage Virtualization
• This virtualization enables all the storage devices on the system to be accessed and be
managed as a single storage unit pool for better maintenance.

• The management and provision of storage are made by the software.

• All the storage is formed in a shared pool from which they can be allotted to any VM on
the system.
 Application Virtualization
• In this virtualization process, the application runs without the need of
installing it into the system, as they run on a virtual environment.

• Types of virtualization:

1. Local application virtualization runs on the host device but runs

in a virtual environment, not in the hardware.

2. Application virtualization, the application is on the server-side,

and it sends some components to the host device according to the
requirement.

3. Server-based application virtualization runs only on the server-

side and sends the only interface to the client system.