Technology

Abstract
This paper tries to review the different network, server and storage virtualization techniques and how the concept of virtualization may be used to address the problems of massive data growth coupled with increased infrastructure complexity while at the same time supporting the cost and performance goals of a modern enterprise. This paper has also discussed the future of virtualization concept.

Introduction
Virtualizations are technologies designed to provide a certain layer of abstraction between systems hardware and the underlying softwares. This concept provides a logical view of Information Systems resources rather than their physical view. Its roots can be traced back to disk portioning which divided a physical server into multiple logical servers. When this server division occurs, each logical server will be capable of running an operating system and systems applications independently (John Waters, 2007)

According to David, Wade and Dave (2006, p4) this concept allows a computer systems resources to be systematically divided or shared by various multiple environments simultaneously. These same environments may interoperate or not and they may not even be aware that they are running within the virtual environments (David, Wade, Dave, 2004, p4)

Todays physical abstraction occurs in several ways, for instance, servers and their workstations no longer need a dedicated physical hardware which is always required to run independent entities because they can easily run within a virtual machine. When these components run as virtual machines, computers hardware is emulated and this particular scenario is presented to an operating system as if the hardware was intact and it truly existed. This technology removes the dependence that the computers operating systems had with their underlying hardware (Chris  Erick, pxx111).
It is also possible to run multiple Virtual management with different operating systems on the same machine simultaneously.

It is mostly a technique employed by different organizations owning at least three servers that are used to consolidate and make better use of the server resources. A well designed virtualization solution consists of servers, storage devices and virtualization softwares that reduce the number of server boxes, mitigate on the likely possibilities of hardware failures and reduces system downtime (Jim Kerr)

Types of Virtualization techniques
There are three different categories of virtualization, there is the storage virtualization, network virtualization and the server virtualization (John Waters, 2007).

Storage Virtualization
This is basically the amalgamation of physical storage devices and it is mostly used in enterprise set ups. Here multiple storage devices are combined into one logical device which appears as a single storage device to users. By using logical resources, there is an abstraction that is created by hiding the complexities associated with the storage devices in use. This abstraction has been found to significantly improve on the management and administration of these storage devices (Whei-Jen Chen et al, 2009).

When storage is treated as a single logical identity regardless of the hierarchy of physical media devices present, applications installed are capable of reading or writing into a single pool rather than the individual devices. Virtual devices reduce the physical one to one devices between storage devices and servers. Storage virtualization may occur on three levels server level, storage network and the storage systems level.

Server level Here virtualization may be implemented by the software that resides on the server itself and it is usually meant for storage devices present. With this particular software, the operating system forces the present server to behave as if it is communicating with a device type but it is just communicating to a virtual disk at this level and it also enables a user to add server and storage capacity easily without disrupting the existing operations (HP, 2008)

Storage Network Level This is an open standard that aids in delivering the many to many  functionality that are critically needed in order to meet the storage requirements, some of the functionalities here may include scaling, virtualization, automation, simplification, interoperability finally investment protection. This particular level also supports management features and the IO price performance which is demanded in modern competitive IT environments and at the same time it avails storage component investment protection that is necessary in reducing capital expense.

Storage System level At this particular level virtualization is implemented on storage array controllers independently of the host. These controllers have the capability of creating virtual disks, snapshots and clones in collaboration with management software. This process is centrally managed in aid of a storage management server and a web browser (HP, 2008)

Network Service Virtualization
Network Service Virtualization negates the need to acquire separate network devices each and every time a service is required from the network. Its value to the organizations and Chief Information Officer is tremendous with the service capable of bringing flexible management interfaces because the network operations have the options of managing many network services instances. Second, network equipment acquisition costs is reduced substantially since network service delivery is shifted away from physical devices to software images that extend network access without necessarily deploying special hardware in each instance that a service is needed. Third, it is easy to extend a network service hence increasing application performance (Nicholas John Lippis, 2007, p6).

Virtualized Network Its building block partitions a network into various logical networks that consists of unique attributes which may include, switching, routing, bandwidth, security e.t.c. Its architecture consists of three components (Nicholas John Lippis, 2007, p7)

Controlling Network Access Here the users are authenticated with authorization. These specific components identifies authorized users and automatically places them to their appropriate logical partition.

Isolating Paths This preserves network isolation across the entire organization. It also maintains traffic which has been partitioned over a routed infrastructure, it also maps isolated paths to virtual LANs and virtual services.

Virtual services  This service provides access to shared or dedicated network services which may involve DHCP, VOIP call management, DNS e.t.c

Server Virtualization
This may be defined as the creation of digital abstractions that represent real physical servers. Server utilization improves on tests and development environments. Physical server may be easily combined into some virtual units housed within few servers in which these virtual servers may continue to provide substantial benefits to their physical counterparts in a reduced physical package which eventually results into hardware and other investments savings (CDW-G, p2)

Server consolidation helps in eliminating obsolete computer systems hardware, it also reduces systems administration overheads and it simplifies disaster recovery scenarios and may as well improve on the overall system availability (Peter Weilnau, 2005, p2)

A virtual machine can be a partition of a certain virtual server which may consist of CPU, memory, network and other resources such as disks which support one operating system installed in a virtual environment. Virtualization infrastructure must consist of host server which runs a virtualization operating system. The virtual host partitions virtual machines so that they may be used by other operating systems in which the host operating system controls the server and the virtualization softwares divides those resources among the many virtual machines and this results into a single server platform running a host operating system that is also capable of acting on behalf of various servers which run a variety of operating systems (CDW-G, p2) and according to Paul Venezia (2007,p25), organization that do not deploy virtualization techniques stand to spend excessive amounts in maintaining their datacenters with a number of organizations already having made the switch towards this concept and also going with innovations within the computer industry, it has already been proved that server virtualization comes with numerous benefits.

Fig 1.0 Diagram depicting server virtualization
Benefits of Virtualization
Enterprises are increasingly being faced with challenges in storing  managing data in todays business environment. Some of these challenges include shrinking IT budget, aggressive competition, economic viability, internal headcount restraints and search of new creative approaches and also some common problems most IT professionals are faced with everyday include costs associated with purchasing additional storage which involves physical space and environmental costs, the operational time, time taken in order to bring the storage into service, administration costs associated with storage allocation, manpower to manage the storage concepts and increasing demand for data integration within a multivendor environment.

When the concept of virtualization is properly utilized, these problems reduce significantly and time, cost and space are economically utilized for the enterprise in order to provide for it the desired value (HP, 2008, p10)

Time
Virtualization within the controller level is likely to offer peak performances, for instance there are some applications that come with features such as the automatic load balancing, this helps the administrator in micro managing data placement, data replication and performance tuning in which these particular benefits enable the IT administrators in decreasing the time required in maintaining and managing their storage while at the same time increasing the power and availability of their available storage environment.

Cost Reduction
This concept also has the capability of reducing the total cost of ownership while still utilizing the existing assets and this has been cited as one of the top reasons most organizations are virtualizing servers.

There is also increased administrators productivity. When applications run in Virtual Machines, when spikes  surges happens or occurs, there is an automatic restarting on the new hardware with the net results being fewer emergency time for administrators, this concept is very easy to build.

Reclaimed Network ports
With most servers using at least two Ethernet port as well as two fiber channels, these ports are sometimes under utilized, Virtual Machines within the network share the ports allowing the re-use of network connectivity per every unplugged physical server (forester consulting, 2009,p9).

Reclaimed Data center capacity
By consolidating servers, space is reclaimed within the data center environment and this in turn also saves on the power bill.

Enhanced Business Continuity and Disaster Recovery
When an organization invests in virtualization they achieve faster application recovery with improved predictability. With virtualization organizations have realized that

There is an improved service level for more system Critical applications are always protected by expensive solutions and the concept also allows failed systems to automatically restart on newer systems.

Virtual machines run almost anywhere Due to their portability virtual machines are easy copied into another location for disaster recovery purposes and the virtual machines may be started on any server that has the users virtualization software installed and running.

Virtual infrastructure protect physical systems enterprises have deployed virtual infrastructure as a backup to their physical servers. By this, enterprises are converting their back up images of their primary systems into virtual machines and they have the option of restarting applications on virtual infrastructure (forester consulting, 2009, p9).

Faster time to market for new Applications
Virtualization enables an expedient response to customer requests much faster than the traditional physical servers. Virtualization is quick because

A lot of steps are eliminated from the build process The process of setting up a server, mounting racks, installing fiber channel, requires technicians and takes a lot of time to complete. In a virtualized environment there is no procurement, physical set up and all steps only take a matter of minutes.

Applications Move rapidly from test to production After an application has been successfully tested administrators have to transport the end product to the production environment, when virtual servers are deployed the same virtual machines that went through quality assurance can be easily copied to the production environment and started right up (forester consulting, 2009,p11)

Future of Virtualization and its impact on Information Technology and Communication
Modern systems are developed on a tiered infrastructure whereby the client, server, applications, and storage are combined into a single functional stack. The various layer of the system are separated and they can be easily changed independently in order to employ best-of-breed technology, but a drawback towards that independence is that the applications installed have to cope with an increasing variety of platform configurations (EMC2, 2008, p20).

In creating a next generation infrastructure, services have to be separated first from the underlying hardware where they reside, this creates standard service interface across the Information Technology stack. With this separation, virtualization will allow the hardware resources to be grouped according to their capacity, computation and connectivity that are coherently managed across an enterprise infrastructure. Now, when this infrastructure has been virtualized, there is the potential of handling significant changes online without disrupting the servers, network and storage equipments (EMC2, 2008, p21)

There is also the Xen virtualization technology that allows users to run many operating systems on a single physical machine with an emphasis on its security, performance and isolation. By the virtue of Xen being an open source project it has a feature known as paravirtualization, this is a feature that that enables making changes to operating systems that run on top of Xen and it also improves on performances and simplifies the Xen feature itself (Diomidis  Georgios, 2009, p155)

According to Toby, Anthony and Robert (2009, p189)Virtualization makes it possible and easy to move to Software As a Service (Saas) oriented system because it is easer for independent software vendors to adopt Saas in the growth of virtualization. This has made it possible to access online services such as QuickBooks which is worlds number one small business accounting software with features such as online banking, there is I-Phone and BlackBerry capabilities, this enable more than 130,000 businesses that subscribe to services such as QuickBooks to manage their enterprises anywhere with or without a computer and they are also able to access Google Apps and Google Apps premier edition. These services relate to virtualization directly or indirectly and are know to impact heavily on Information Technology (Toby, Anthony, Robert, 2009, p189).

Conclusion
Virtualization is a new concept that modern enterprises use to maximize their use of computing resources. A well designed solution mitigates possible hardware failures and comes with proper techniques in place that significantly reduce the risks of downtime.

With virtualization being addressed at all levels of modern technologies, most powerful application of this technology can be found at the network, server and storage systems level and with modern solutions, different enterprise across the world can take advantage and deploy the various solutions available that are designed specifically for open ended systems.

With this particular concept in hand, organizations whether big or small may try deploy this particular technology in order to understand fully its benefits as it is known to reduce cost of maintaining the IT budget which also takes a huge chunk of the corporations budget.