On the Evolution of Virtualization and Cloud Computing: A Review

Abstract

Cloud computing, the technology that makes it possible for computing resources to be provisioned to clients / subscribers over long distances, as well as its component technology – virtualization, which makes it possible for multiple guest systems to co-reside on a single host machine and share the computing resources of the host, have both become very popular technologies that have witnessed giant improvements in the 21 st century. This is a review paper that presents an overview of the technologies of virtualization and cloud computing, tracing their history and evolution down a timeline to what they have today, and providing pointers to prospects of future advancements to virtualization and cloud computing.

Full text

Journal of Computer Sciences and Applications, 2014, Vol. 2, No. 3, 40-43
Available online at http://pubs.sciepub.com/jcsa/2/3/1
© Science and Education Publishing
DOI:10.12691/jcsa-2-3-1
On the Evolution of Virtualization and Cloud
Computing: A Review
Awodele Oludele, Emmanuel C. Ogu*, Kuyoro ‘Shade, Umezuruike Chinecherem
Department of Computer Science and Information Technology, School of Computing and Engineering Sciences, Babcock University,
Ilisan-Remo, Ogun State. Nigeria
*Corresponding author: ecoxd1@yahoo.com
Received November 27, 2014; Revised December 20, 2014; Accepted December 25, 2014
Abstract Cloud computing, the technology that makes it possible for computing resources to be provisioned to
clients / subscribers over long distances, as well as its component technology – virtualization, which makes it
possible for multiple guest systems to co-reside on a single host machine and share the computing resources of the
host, have both become very popular technologies that have witnessed giant improvements in the 21st century. This
is a review paper that presents an overview of the technologies of virtualization and cloud computing, tracing their
history and evolution down a timeline to what they have today, and providing pointers to prospects of future
advancements to virtualization and cloud computing.
Keywords: virtualization, cloud computing, computing resources, clients / subscribers
Cite This Article: Awodele Oludele, Emmanuel C. Ogu, Kuyoro „Shade, and Umezuruike Chinecherem, “On
the Evolution of Virtualization and Cloud Computing: A Review.” Journal of Computer Sciences and
Applications, vol. 2, no. 3 (2014): 40-43. doi: 10.12691/jcsa-2-3-1.
1. Introduction
With the successful delivery of the first message over
the Advanced Research Projects Agency Network
(ARPANet) at the peak of the American Cold War, it was
instilled in the minds of the over 1000 witnesses present
that a technological revolution was soon to be born. The
possibility of remote access to files was confirmed. On
January 1, 1983, with the successful establishment of the
first TCP/IP communication, the internet was birthed [1].
The advent of the Internet was welcomed and found its
first use in research and academics. But as the internet
grew over the years, it gradually crawled out of the
domain of research and academics to playing vital roles in
healthcare and in the workings of various governments
and economies [2,3], and this helped to further convince
cynics that this new technology had come to stay.
2. Technological Evolution
The birth of the internet was however, foretold about
two decades earlier when John McCarthy, speaking at the
MIT Centennial in 1961 was quoted as saying, “If
computers of the kind I have advocated become the
computers of the future, then computing may someday be
organized as a public utility just as the telephone system is
a public utility... The computer utility could become the
basis of a new and important industry. [4]” Little did he
know that it wasn‟t going to be very long before this
dream of his came to reality.
By the 1970s, mainframe users saw the first
implementation of virtualization and symmetric
multiprocessing, where different users could use the
resources of a single machine to execute different processes
concurrently. But as the Internet continued to expand,
organizations, researchers and academicians began to
grapple with concerns relating to the high cost of
computers at the time and only sparsely intermittent
computational needs; they could not justify investing at
high costs in a computer that would be idle for most of the
time. To assuage theseconcerns, entrepreneurs came up
with the idea of “renting” time, making it possible for
organizations and users to either own or subscribe to
computing resources at much lower costs [5].
It now became possible for users to access large-scale
mainframe computer systems from thin clients/terminal
machines, often referred to as “static terminals” (see Figure 1)
because they were used mainly for communications but
had no internal processing capabilities. This idea helped to
enhance the efficiency of expensive mainframe systems
and reduce idle periodsby allowing multiple users to share
both the physical access to the computer from multiple
terminals as well as the processing resources (CPU time);
thus, allowing for greater returns on investment for
companies that practiced such [6]. It is this technology
that evolved through various nomenclatures – such as
Remote Job Entry in the 1950s [7], Shared and Dedicated
Web Hosting (which are forms of Virtual Web Hosting)
around 1995 to 1997 [8,9], Virtual Private Server (VPS)
Hosting around 1998 [10], Grid/Utility Computing [5,11]
– to become Cloud Computing (CC) about three decades later.
Following the standardization of the Internet and its
protocols in the 1990s, around 1995, the company –

41 Journal of Computer Sciences and Applications
SalesForce began hosting and distributing customer
relationship management software over the internet on a
subscription basis. The company hosted a platform on
their servers that enabled application developers to build
applications that could be hosted on these servers. This
was one of the pioneer instances of hardware
virtualization, which loosely means, “hosting a computer
inside another computer”, and cloud computing [12].
Figure 1. Early years of Cloud Computing [13]
3. Cloud Computing
Cloud Computing (CC) is defined by the United States
National Institute of Standards and Technology (NIST) as
“a model for enabling ubiquitous, convenient, on-demand
network access to a shared pool of configurable
computing resources (e.g., networks, servers, storage,
applications, and services) that can be rapidly provisioned
and released with minimal management effort or service
provider interaction; having characteristics of on-demand
self-service, broad network access, resource pooling, rapid
elasticity and payment per usage of various business
models. [14]” Cloud computing services are delivered
through three standardized service models: the
Infrastructure as a Service (IaaS), Platform as a Service
(PaaS) and the Software as a Service (SaaS) Models.
Figure 2 illustrates the service models of cloud computing,
and some popular services that are provided through these
models.
Figure 2. Cloud Computing Service Models[15]
The first / foundational layer of Cloud Computing is the
IaaS layer. The products here relate to hardware and
associated services such as: general processing, servers,
storage devices, database management, and all other
hardware related services that are offered as a service to
the end user. The next layer is the PaaS layer upon which
developers can build and test applications that run on the
IaaS, either for the IaaS layer itself or for the SaaS layer
above it. The topmost layer is the SaaS, and this deals
exclusively with applications for end users [16].
CC service models today are deployed either as Private
Clouds (cloud infrastructure provisioned for exclusive use
by a single organization comprising multiple consumers),
Community Clouds (cloud infrastructure provisioned for
exclusive use by a specific community of consumers from
organizations that have shared concerns such as: mission,
security requirements, policies, and compliance
considerations), Public Clouds (cloud infrastructure
provisioned for open use by the general public) or Hybrid
Clouds (cloud infrastructure comprising two or more
distinct cloud infrastructures, whether private, community,
or public, that remain unique entities, but are bound
together by standardized or proprietary technology
enabling data and application portability, such as cloud
bursting for load balancing, between clouds). The
interactions between these various modes of deployment
are illustrated in Figure 3 [16].
Figure 3. IaaS Deployment Variants[16]
4. Virtualization
Virtualization is the technology that allows multiple
Virtual Machines (also called guest machines) to run on a
single physical machine (also called host machine) and
share the resources of the physical machine [17]. This
makes it possible for a single physical server to host many
guest virtual machines (VMs), operating systems, and
applications without the additional cost and complexity
that result from running these multiple physical machines
individually [18].
Virtualization could occur in various forms. It could be
server-based [22], system based [19], storage virtualization
[27], desktop virtualization [28] or network virtualization
[26]. It could also be hypervisor-based (if a piece of software
known as a hypervisor or virtual machine monitor is used
to achieve virtualization) or non-hypervisor-based.
Despite variations in organization and architectural
implementations, the following core components are
generic to virtualization as shown in Figure 4 below:
Figure 4. Core Components in Virtualized Architectures (Source: [19])

Journal of Computer Sciences and Applications 42
Virtualization is a very fundamental technology that
lies at the heart of the operations of modern Cloud
Computing Infrastructure [19]. This technology is
important to cloud computing because it provides the
abstraction that cloud computing enjoys by taking a
physical resource such as a server and dividing it into
virtual resources called virtual machines (multiple
subscribers). In case of server consolidation, many small
physical servers are replaced by one larger physical server,
to increase the utilization of costly hardware resources
such as CPU time [20]. The interactions that take place
between the technologies of virtualization and cloud
computing are illustrated in Figure 5.
Figure 5. Virtualization and Cloud Computing[21]
The abstraction from the hardware state provided by
virtualization allows not only multiple operating systems
to coexist on the same hardware, but for one VMM to run
on multiple different networked physical systems
concurrently [19].
5. Cloud Computing in the 21st Century
Two additional factors that have significantly
distinguished this new technology from its predecessors
and greatly altered its market dynamics in recent years are
the speed, dynamism and “far-reach” of the Internet,
which makes it possible to transport and deliver
computational resources at high speeds, across long
distances, and at reduced cost; and the ubiquity of
personal computers coupled with the tendency to own
computers that satisfy “peak” against “average” need for
computational power, directly leaving a good reserve of
computational resources idle [5].
Today, Cloud computing is gradually coming to bear in
reality as the most formidable path to business and
organizational growth and has gained rapid interest and
prominence over the past decade. The reason for this rapid
growth cannot be far-fetched. Cloud computing simply
makes very efficient and flexible, the task of scaling
different business services to meet very dynamic business
needs; the shared infrastructure and services they provide
make it a more prudent venture when compared with other
traditional approaches of hosting each of these
infrastructure and services locally.
[22], revealed that 90% of organizations had started
implementing Server Virtualization in some form as a part
of their IT Infrastructure. This opens the mind to the
reality that CC may actually hold the key to formidable
business and organizational growth; and the reason for this
is simply because CC enhances the flexibility and efficiency
associated with scaling different business services to meet
very dynamic business needs [23].
Today, virtualization and cloud computing find its use
in business model simulation and testing, computer aided
designs of business models, and business process
migration, fault tolerance enhancements and backups [13].
6. Prospects for Virtualization and Cloud
Computing
Some of the prospects which to virtualization and CC
have been revealed in researches by [13], [24] and [25] to
include: more favourable policy enactments and
implementations, ubiquity, centralized storage and access-
on-demand, data portability across various cloud
platforms, increased consumer-base for private and public
clouds, less security concerns and more standardization.
An October 2014 survey carried out by Forrester
Consulting on behalf of Infosys revealed by 81% of
companies surveyed that cloud computing is no longer
driven by cost savings anymore, but by agility, simplicity
and a unified view of IT. This result is expected to
increase exponentially within the next few years as more
organizations are expected to turn to the cloud for these
reasons.
7. Challenges of Virtualization and Cloud
Computing
Because Virtualization and Cloud Computing are in
what seems to be a symbiotic relationship, it would be no
gainsaying that challenges faced by one would equally
affect the other. The most prevalent challenge of
virtualization and cloud computing relate to security. A lot
of research has gone into the finding and characterizing
these challenges in recent years. One of such researches
was by [23]. Figure 6 below summarizes the findings of
the research:
Figure 6. Various categories of Cloud Security threats [23]
8. Conclusion
Virtualization and Cloud Computing have come to stay
and have carefully carved a niche for themselves in the

43 Journal of Computer Sciences and Applications
world of business and IT generally. With the many
advantages and possibilities provided by these two
technologies, and the exciting prospects that have been
envisaged, it would be safe to say that these are
technologies that would continue to revolutionize and
transform many areas of human endeavour for years to
come.
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