Virtualization allows multiple operating systems and applications to run on a single hardware device by dividing the resources virtually. It provides isolation, encapsulation, and interposition. There are two types of hypervisors - Type 1 runs directly on hardware and Type 2 runs on an operating system. Virtualization can be applied to servers, desktops, applications, networks, and storage to improve utilization, security, and manageability.

1. Virtualization

2. Virtualization
• Virtualization is a technology that helps us to install different
Operating Systems on a hardware. They are completely separated
and independent from each other.
• This blend of virtualization technologies - or virtual infrastructure -
provides a layer of abstraction between computing, storage and
networking hardware, and the applications running on it
• Virtualization - Various techniques and methods of creating a
virtual (rather than actual) version of something, such as:
– Computer hardware platform
– Operating System (OS) – Virtual Machine or VM
– Storage device
– Network resources

3. Virtualization (cont.)
Hardware
‘Nonvirtualized’ system
A single OS controls all hardware
platform resources
Virtualized system
It makes it possible to run multiple Virtual
Containers on a single physical platform
Hardware

4. History of Virtualization
• Virtualization is an approach that was developed by the pioneers
of computing systems, IBM and Boroughs (now Unisys) back in
the ancient days of computing, the 1960s.
• It involved using unused computing resources to create an
artificial, but useful, view of system capabilities.
• In the 80’s and early 90’s the industry moved from leveraging
singular mainframes to running collections of smaller and
cheaper x86 servers. As a result the concept of virtualization
become less prominent. That changed in 1999 with VMware’s
introduction of VMware workstation.

6. Virtual Machines (VM)
• A machine with virtualization software can host
numerous applications, including those that run
on different operating systems, on a single
platform.
• Software that supports multiple operating systems
on a single computer.
• Each operating system is it’s own “virtual machine”
with it’s own:
– Operating system, RAM, Storage
• Shared CPU
• The host operating system can support a number of virtual machines, each of
which has the characteristics of a particular OS.
• The solution that enables virtualization is a virtual machine monitor (VMM), or
hypervisor

7. Virtual Machines (cont.)
Virtual
Machine
Server
• Instead of being stored on the local computer,
the VMs may be stored on a remote server.

8. • A hypervisor is a piece of computer software, firmware or hardware that creates
and runs virtual machines. (i.e virtual machine manager or virtual machine
monitor
• Host machine: The computer that runs and has one or more virtual machines.
• Each virtual machine is called a guest machine.

9. Role of a Hypervisor
• The explanation of a hypervisor up to this point has been fairly
simple: it is a layer of software that sits between the hardware and
the one or more virtual machines that it supports. Its job is also
fairly simple. The three characteristics are,
• Provide an environment identical to the physical environment
• Provide that environment with minimal performance cost
• Retain complete control of the system resources

10. Classes of Hypervisors
• There are two classes of hypervisors, and their names,
Type 1 (Native of Bare Metal Hypervisor) and
• Type 2 (Hosted Hypervisor), give no clue at all to their
differences. The only item of note between them is how
they are deployed, but it is enough of a variance to point
out.

11. Type 1 Hypervisors
• Type 1 hypervisors run directly on the server hardware without an
operating system beneath it.
• Because there is no intervening layer between the hypervisor and
the physical hardware, this is also referred to as a bare-metal
implementation.
• Without an intermediary, the Type 1 hypervisor can directly
communicate with the hardware resources in the stack below it,
making it much more efficient than the Type 2 hypervisor.
• Guest operations are handed off and, as such, a guest cannot
affect the hypervisor on which it is supported.
Example: VMware ESXi, XenServer

13. Type 2 Hypervisors
• A Type 2 hypervisor itself is an application that runs a top a traditional operating
system.
• Often Type 2 hypervisors are easy to install and deploy because much of the
hardware configuration work, such as networking and storage, has already been
covered by the operating system.
• Type 2 hypervisors are not as efficient as Type 1 hypervisors because of
thisextra layer between the hypervisor itself and the hardware.
• Type 2 hypervisors are also less reliable because there are more points of
failure: anything that affects the availability of the underlying operating system
also can impact the hypervisor and the guests it supports.
• A well-known example of a hosted hypervisor is Oracle VM VirtualBox. Others
include VMWare Server and Workstation, Microsoft Virtual PC, KVM, QEMU and
Parallels.

15. Features of Virtualzation
• Partitioning: In a single physical system by partitioning the
available resources it supports multiple applications and operating
systems.
• Isolation: Each virtual machine runs in an isolated manner from its
host system and other virtual machine. Its benifit is if any VM
crashes, the other VM and the host system are not affected.
• Encapsulation: Each VM is encapsulates its file system. It works
like an independant guest software configuration.
• Interposition: In VM all the new guest actions are performed
through the monitor. these actions are done without the knowledge
of the OS.

16. Types of Virtualization
• Today the term virtualization is widely applied to a
number of concepts, some of which are described
below:
– Server Virtualization
– Client & Desktop Virtualization
– Services and Applications Virtualization
– Network Virtualization
– Storage Virtualization

17. Server Virtualization
• It is virtualizing your server infrastructure where you do not have to
use any more physical servers for different purposes.
• With server virtualization one physical machine is divided many virtual
servers. At the core of such virtualization is the concept of a
hypervisor (virtual machine monitor). Server virtualization has a large
number of benefits for the companies making use of the technology.
Among those frequently listed:
– Increased Hardware Utilization – This results in hardware saving, reduced
administration overhead, and energy savings.
– Security – Clean images can be used to restore compromised systems.
Virtual machines can also provide sandboxing and isolation to limit attacks.
– Development – Debugging and performance monitoring scenarios can be
easily setup in a repeatable fashion. Developers also have easy access to
operating systems they might not otherwise be able to install on their
desktops.

18. Application/Desktop Virtualization
• Virtualization is not only a server domain technology. It is being put to a number of uses
on the client side at both the desktop and application level.
• Such virtualization can be broken out into four categories:
– Local Application Virtualization/Streaming
– Hosted Application Virtualization
– Hosted Desktop Virtualization
– Local Desktop Virtualization
Client & Desktop Virtualization : This is similar to server virtualization, but this time is on
the user’s site where you virtualize their desktops. We change their desktops with thin
clients and by utilizing the datacenter resources.
Services and Applications Virtualization: The virtualization technology isolates
applications from the underlying operating system and from other applications, in order to
increase compatibility and manageability. For example – Docker can be used for that
purpose.

19. Client & Desktop Virtualization
Services and Applications Virtualization

20. Network Virtualization
• It is a part of virtualization infrastructure, which is used especially if you are
going to visualize your servers. It helps you in creating multiple switching,
Vlans, NAT-ing, etc.
• Network virtualization involves platform virtualization, often combined with
resource virtualization. Network virtualization is categorized as either
external, combining many networks, or parts of networks, into a virtual unit,
or internal, providing network-like functionality to the software containers on
a single system.
• Virtual Private Networks (VPNs) have been a common component of the
network administrators’ toolbox.
• Virtual LANs (VLANs) are another commonly used network virtualization
concept.

21. The following illustration shows the VMware schema:

22. Storage Virtualization
• This is widely used in datacenters
where you have a big storage and it
helps you to create, delete,
allocated storage to different
hardware. This allocation is done
through network connection. The
leader on storage is SAN.
• Storage virtualization refers to the
process of abstracting logical
storage from physical storage.
• General benefits of storage virtualization
include:
– Migration.
– Utilization
– Management