The advantages of server virtualization are broadly recognized, and a major part of companies has acquired virtualization technologies. Companies are virtualizing mission-critical workloads, while they have to contemplate its security and pliability. The paper will analyze the concept of virtualization, its advantages and disadvantages, and will eventually address “VMWARE vSPHERE” product.


Modern Information Technology infrastructure performs in a completely discrepant manner comparing to the way it used to work ten years ago. Despite the data center looks analogous, meaning that there are storage and servers, the way it operates has changed essentially. Organizations currently recognize virtualized settings to be hazardous. Due to the fact that virtualization adopters became more security conscious, the companies struggled to discover the most efficient and effective methods to proactively defend virtualized settings. The current paper demonstrates that while numerous companies are leveraging security of the existing data centers to solve innovatively security and compliance problems, there is an elevating acceptance of virtualization-aware and virtualization-specific security resolutions for mission-critical applications and sized cloud-ready deployments.

The notion of virtualization was previously enlarged to the x86 server market, since companies required an innovative service. At that time, the deployment of the service began with acquisition, installation and configuration of costly hardware. Moreover, individual servers were calibrated to accommodate sharp burdens. In fact, the companies did not want their customers or end users to suffer from insufficient RAM or low quantity of disks.

Nevertheless, even though servers were sized for sharp loads, usual utilization of the majority of resource constituents, including processors, RAM and storage, were unable to deal with equipped hardware to the maximum. It practically means that companies load each individual with work to the top across all services. This was also the time when the technology was booming, while the innovative services appeared to be developing at a fast pace. In order to accommodate innovative workloads, individual servers were hired to impede prospective conflicts between resources and software.

Virtualization Technologies

A virtual machine is a software computer, which similarly to a physical computer, runs applications and operating system. The facts show that hypervisor operates as a program for operating virtual appliances, permitting computing resources consolidation. Moreover, each virtual machine and appliance incorporates its own virtual, or software-grounded hardware, incorporating a virtual CPU, hard disk, network interface, and card memory [1]. The facts demonstrate that the hypervisor has to be installed on the physical hardware in a virtualized data center, where it operates as an appliance for virtual implements. Therefore, the hypervisor equips physical hardware resources in dynamical manner to virtual appliances, since it sustains the performance of the virtual implements. The hypervisor provides virtual machines with a possibility to perform with some degree of independence from the incumbent physical hardware. For instance, a virtual appliance can be shifted from one physical host to another [1]. On the other hand, virtual disks can be shifted from one kind of storage to another, without affecting the operation of the virtual appliance. Because virtual implements are separated from particular incumbent physical hardware, virtualization gives a possibility to strengthen physical computing resources encompassing CPUs, storage, networking, and memory into resources reserves, which can be flexibly and dynamically accessible to virtual machines [1].

The facts demonstrate that physical security implements were not created to secure such virtual infrastructures as hybrid and private clouds and virtualized data centers. This “traditional” security superintendence relies on physical devices utilized on physical networks or on the circumference of the data center. They do not appear to be well-adapted to defend virtual assets for two major reasons. First, it is highly complicated and unmanageable to direct traffic from inside of the virtual infrastructure to a physical security control situated beyond the virtual setting. For instance, it might be performed technically via VLANs. Nevertheless, the dynamic character of the virtual infrastructure appears to make this resolution complicated to maintain and manage in reality [2]. Secondly, traditional circumference implements are highly efficient at exploiting and enforcing course- crystallized security regulations across a huge quantity of network traffic. It is important to complement this with fine-crystallized security regulations enfolded around each workload or group of workloads in a virtual infrastructure. In fact, this technique of security, which is also presented as micro-division, requires the use of software-grounded virtualized security superintendence unfolded within the virtual fabric itself [2].
Virtualization, or x86 server virtualization as popularized by VMware, has drastically changed the data center within the decade. The concept, which began in a form of a workstation technology essentially for testing, evolvement and labs developed into data center infrastructure for server consolidation, later into high usage with effective operating and capital spending, and currently into a fundamental ground for cloud computing. Currently, the quantity of global virtual servers has excelled the quantity of physical servers with virtualization not merely admissible in production environment but mission-crucial. Companies are not merely amalgamating racks and servers, but tools that frequently redesign the whole facilities and sites with data center strengthening and conversion and “virtual- initial” regulations, including the projecting admission, which any innovative workloads deploy in a virtual machine. In addition, the acquittal have to be equipped for exclusions, which require a physical machine [1].

Mixed Trust Zones

When virtualization shifted from test into production setting, the problems and concerns about security appeared. There is an assertion that there has been no alterations in security resolutions and security stance at the time when existent workloads changed to “P2V” (physical-to-virtual) [1]. On the contrary, other scholars revealed both operational and architectural concerns. A number of the earliest virtual security debates concerned “mixed trust zones”, outlining the hazards of hosting virtual servers of discrepant data susceptibility or Internet subjection on the analogous hypervisor occurrence (meaning physical server host). Susceptible data encountering the hazards of being ruptured should compromise a virtual server and the principal hypervisor VM isolation [1]. The facts demonstrate that the PCI Council has joined the discussion, since discrepant servers, such as ones stockpiling credit card numbers or other information of payment card industry, will habitually be preserved by physically segmented network firewalls and separated by function in accordance with the PCI Council’s Data Security Standards (DSS). In fact, the PCI Council virtualization Special Interest Group (SIG) did not provide limitations on the use of virtualization technology nor mixed trust zones. Nevertheless, the usage of mixed trust zones can broaden the extent of compliance audit to supplementary non-DSS virtual servers, which can elevate regulative and audit spending and tentative [2].

“DMS Collapsing” and Inter-VM Visibility

Mixing trust zones appeared to be pragmatic security issue as well due to inter-VM traffic visibility. The canonical exemplification stands for the “DMS collapsing” of a specific Internet-encountering three-layer web application onto a separate physical host. The distinct virtual servers for the web demonstrate that the database layer and application suspend the analogous hypervisor and virtual switch. Security virtual appliances appear to be a logical solution, positioning network security engines into VM’s, which can currently be re-placed into the virtual switch traffic [1].

North-South vs. East-West

Another option includes the string multiple VLAN, used for application tier or each zone. It supposes that each virtual switch of the physical host changes all the way up the physical network to a more pivotal accumulation layer, in which the more traditional firewall implementation is capable of inspecting and enforcing network zones. It presupposes that the inter-VM traffic appears to be directed more “north-south” on contrary to the conventional “east-west” traffic inside the virtual switch. This is not a real problem for VM traffic, which traverses discrepant hypervisor requirements, since this traffic leaves the physical host in any case [2]. Nevertheless, a three-tier application located on a shared host can result in the “hair pinning”, in which traffic exits as a physical host merely to ] revolve right around the firewall and back down to another VM on the analogous host. Because active migration (for instance VMware vMotion) and dynamical resource combination might move VM’s around regularly, it cannot be anticipated how and when inter-VM traffic will appear. A network I/O latency demonstrates that server-server traffic existing in the physical host might augment approximately 10-20 µs (or 40 percent) latency per round-trip against solid virtual switch traffic, on top of any latency introduced by the security appliances or physical switch fabric [2]. The supplemented latency might be aggravated to 100 µs or even more when greatly employed hosts have numerous VM’s lining network traffic on the physical NIC [1]. In fact, hair-pinning incorporates increase in the two-fold impact of both receiving and sending VM’s required to pass via the physical NIC. This does not presuppose that physical security implements are not appropriate, but sustain because of the appointed decreased latency.

Advantages and Disadvantages of Virtualization

The usage of virtualization technologies appears to have numerous advantages including flexibility, agility, and cost effectiveness. Nevertheless, the introduction of virtualization can also introduce new challenges. Firstly, it introduces an innovative virtual network fabric, which appears to be blind to physical security implements. Secondly, it introduces an innovative hazard surface, meaning the hypervisor. Thirdly, it induces an all-vigorous virtual administrator, subsiding and collapsing functions. Fourthly, machines turn into files, resulting in mobility, abrupt alteration and huge opportunities for theft. As the same time when IT does require modernizing their own corporate governance and security operations in the face of virtualization, the net affect of virtualization on security can appear to be highly beneficial [3]. Virtualization enhances security by making it more flexible and context-conscious. Security appears to be precise, easier to operate and control and less costly to develop on the contrary to traditional physical security when applying software-grounded security resolutions [2].

In regards with businesses with restricted funds, virtualization helps them stay on budget by neglecting the requirements to invest in huge quantities of hardware. Virtualization also assists businesses with restricted IT personnel by automating routine IT assignments and consolidating resource management. In addition, personnel enjoy the magnificence accessibility to their data anywhere and anytime, without applying any implementations [2].

Reduced IT Costs

Virtualization assists businesses in achieving cutting costs in numerous areas. Julia Lee, who appears to be a senior product-marketing manager at virtualization resolutions provider in VMware, separated the costs into three categories, including energy economy, capital expenditure economy, and operational expenditure economy. Thus, capital expenditure savings demonstrate that virtualization provides organizations with a possibility to lower their IT spending by demanding fewer hardware servers and connected resources to obtain the analogous level of computing accomplishment, accessibility and scalability [3]. Secondly, operational expenditure demonstrates that when their servers are virtualized, IT personnel can seriously lower the continuing and progressing management and administration of manual and time-expending operations through automated processes, leading to lower operational costs. Finally, data-center and energy-effectiveness demonstrate that when organizations lower the scale of their server footprint and hardware, they decrease their energy consumption, cooling power and data-center square footage, thus leading to lower costs [2].

Despite the virtualization eventually reduces IT expenses, its major disadvantage is the fact that it demands higher up-front expenditures. This is primarily caused by server costs associated with the process. In fact, servers can be efficiently changed into virtual servers; however, they are valued and priced more than conventional servers. The majority of organizations decide to spend more money to implement desktop virtualization and server, than to later invest in upgrade of desktop software and servers. Thus, while considering expenditures, businesses are supposed to observe alternatively virtualization in a form of a long-range venture. In fact, the return on investment (meaning ROI) comes over time [3].

Efficient Resource Utilization

In addition to lowered IT costs, virtualization permits businesses to gain back the major part of their investment in resources and hardware. The principal advantage of virtualization is the capability to consolidate and incorporate a number of required servers, which, in turn, permits businesses to run multiple operating system workloads and several applications on one server. Instead of 20 servers, the companies can require only one. For instance, a number of company’s clients have incorporate up to 30 or 40 workloads on a sole server, which actually provides them with a better usage of the accessible physical space [2].

On the other hand, traditional infrastructures, which utilize several servers, do not actually use the maximum of their setups. Numerous of these servers do not usually use more than 2 to 10 percent of the server hardware resources. Thus, the virtualization can help in running several virtual servers on a sole virtual host and make better usage of the available resources. This assists businesses in better management of their resources and effective utilization [1]. Virtualization empowers resource management, the crucial praxis of applied limitations, programming and separation to elevate the pliability of computing settings. One sample of resource management stands for load librations, which assist in enhancing performance and utilization. Since server workloads differ, virtualization permits the proliferation of work to underused servers. This also helps in speeding up production and assists in preventing needless stoppage [3].

Nevertheless, the disadvantage stands for the fact that not all applications and servers appear to be virtualization-friendly. The typical major reason of inability to virtualize an application or server is the fact that the application vendor did not corroborate it yet, or recommend it [1].

Nonetheless, virtualization appears to be greatly scalable. It allows businesses generate supplementary resources as requited by numerous applications, for instance by readily supplementing additional servers. It is performed on request and as-required foundation without any essential investments of money or time [3].

IT can generate innovative servers rapidly, as they do not require acquiring innovative hardware each time they have a need of a new server. Thus, when the resources are accessible, there is a possibility to design an innovative server in a limited number of clicks of a mouse [2].

In addition, the effortlessness of generating supplementary resources assists businesses in scaling, as they increase and develop. This outline can be a perfect option for small businesses, which are rapidly growing, or businesses, which are utilizing their data center for development and testing. Nevertheless, businesses should understand that one of the major objectives and benefits of virtualization is the effective use of resources. Thus, they should be cautious not to let the facility of generating servers lead to the negligence of apportioning resources. The facts demonstrate that server stretching appears to be one of the unintentional outcomes of virtualization. When administrators recognize how easy it is to augment innovative servers, they begin to add a new server to everything. The companies understand that instead of 6 to 10 servers, they are currently managing 20 to 30 servers [3].

In addition, security in a virtualized data center can also be more automatized. Virtualization security provides data center administrators with authority to equip automatically secure machines. In addition, security policies adhere to workloads when they shift, automatically establish firewall rule sets for groups of servers and automatically impose compromised isolation or out of compliance assets. Virtualization has the power to make data centers even more secure and compliant unlike their physical elements with the appropriate processes and technology.

The facts demonstrate that security professionals require acknowledging innovation and adjusting security operations to accommodate them. Otherwise, virtualization might constitute a solid security hazard. In fact, recognition of these alterations reveals that independent 3rd party, including NIST and PCI, has transfigured their recommendations and norms [3]. Their renewed identifications recognize that without relevant training and technology, virtualization and cloud systems can induce essential security and compliance lacunas. These lacunas incorporate unsecured networks, access control failures, detriment of alteration controls, innovative hazard surfaces, failures in segregation of obligations and consolidation of privilege. Virtualization security refers to these possible lacunas at the same time lowering the costs and complexity [1].

Types of Visualization

This paper primarily focuses on x86 server virtualization offered by such companies as VMware [2]. Nevertheless, there are several discrepant types of virtualization options. This part briefly outlines some of them. Despite the fact that these are discrepant types of virtualization, these kinds are generally incorporated in people’s x86 server virtualization projects [2].

Network Virtualization

VLANs, meaning virtual networks, are being used already for a long time. A VLAN stands for a collection of systems, which interface in the analogous broadcast realm, regardless of the physical settlement of each intersection. The creation and customization of VLANs to a physical networking hardware demonstrates that a network administrator can be positioned on two different hosts, meaning, for example, the one in Shanghai and the one in the New York City. These appear to be the hosts, which are actually located in the analogous physical network. The hosts will commune with each other under the specific outline. This particular withdrawal makes it easier for organizations to despoil from merely utilizing physical relationships by outlining networks and to be capable to create less costly networks, which are versatile and meet continuous business requirements [3].

Application Virtualization

Virtualization is directly related to withdrawal. When it concerns application virtualization, traditional applications appear to be enfolded into a container, which permits the application to regard that it is operating on a former sustained platform. The application utilization demonstrates that it has access to the resources, which it requires to operate properly. Regardless the fact that virtualization applications are not actually “installed” in the traditional manner, they are still performed on former systems [2].

Desktop Virtualization

Desktop and server virtualization appear to be on two sides of the analogous coin. Both incorporate virtualizations of the complete systems, but there are some principal discrepancies. Server virtualization incorporates the abstraction of server-grounded workloads from the incumbent hardware, which is later supplied to clients on a regular basis. The facts demonstrate that clients do not observe any discrepancies between a virtual and physical server. On the contrary, desktop virtualization turns the traditional desktop into virtual desktop and shifts the implementation of that customer workload to the data center. These workloads can be later approached through a number of diverse methods, including by clients [2].

WMware Site Recovery Manager

VMware Site Recovery Manager provides the industry-guiding resolutions with a possibility to empower application accessibility and variability across sites in private cloud settings [4]. It is a disastrous recuperation trial, implementation, and projected migration commodity tailor created for VMware virtualized data centers. The facts show that it strengthens the capacity of preservation counterparts and virtual machine inconsistency to equip automated calamity recovery trials and implementation as well as projected migrations of virtual machines between active locations and sites. The regulated automation amalgamated with storage duplicating outputs with incompatible abilities to meet RPO and RTO demands when contrasted to physical servers and legacy disaster recovery projects [4].

For the major part of realignments, the Site Recovery Manager infrastructure and conclusive architecture is reflected between two sites. Each site incorporates storage, which repulses between sites, meaning vSphere hosts, which equip compute resources for operating virtual machines, and finally the software, which is utilized to direct the storage, vSphere, and SRM. In addition, each site also incorporates other omnipresent infrastructure constituents, including networking, firewalls, physical servers, directory services, and authentication. In fact, the application adapts two major sites, meaning the Active/Active design and the traditional Active site/DR site design [4].

Recovery Point Objective (RPO)

Application’s RPO is an industry normal metric, which defines the indemnity sharp end or maximum acceptance of data deprivation in cases when a disaster recovery project is accomplished. RPO is outlined in a disaster repossession project itself for a selected data set or tier and appears to be later utilized as a measure to define the prosperity or collapse of an accomplished plan both actual and test [5]. A multitude and diversity of RPOs subsists different recovered data or application tiers. RPO is usually balanced in regards with minutes or hours. For instance, in one hour RPO can be connected to a tier 1 SQL Server application database. This presupposes that an upper limit of one hour of data might be ruined/destroyed or the implemented disaster recovery plan might restore data to a point within one hour or less after the disaster time. RPO is enhanced by elevating the intervening time at which data is replicated or backed up to the restoring site [5].

Recovery Time Objective (RTO)

RTO appears to be an industry normal metric, which defines the upper limit of the permitted restoring time at moments of a recovery plan execution. RTO is outlined in a disaster-restoring plan itself for a selected data set or tier that is utilized as a measuring implement to define the prosperity or collapse of an implemented plan whether actual or testing. A number of RTOs might be used for highly different applications tiers or recovered data. Similarly to RPO, RTO is usually calculated within minutes or hours. For instance, a six-hour RTO might be connected to a tier 1 SQL Server application database [4]. In fact, this presupposes an utmost of six hours might pass from the disaster time until the period when SQL Server application database is accessible again. The launching point for the RTO measuring might differ between companies but has to be precisely outlined in the disaster restoration plan. For instance, the RTO computation might be grounded on the accurate and detailed time of the disaster, which is typical for service suppliers, or it might be grounded on a company’s official statement of a disaster, rather than the disaster occasion itself, which appears to be the main launching point of data inaccessibility and application. Announcement of a disaster stands for a procedure, which affects and consequently declares itself, spending computable quantities of time. The RTO measuring might or might not be the agent in the time necessary to make a decision. In fact, RTO is typically enhanced by sound records, operations, automation, virtualization, and data integrity [4].

Fast and Reliable IT Disaster Recovery

This application allows performing permanent non-subversive testing to ensure IT disaster restoring compliance and predictability and obtain rapid and dependable recovery utilizing completely automatized workflows and supplementary Software-Defined Data Centre (SDDC) resolutions [5].

Zero-Downtime Application Mobility

It also allows moving active virtual machines between sites over metro intervals by utilizing disaster restoring plans to arrange and adapt vSphere cross-vCenter vMotion processes, eluding all stoppage [5].

Simple and Policy-Based Management

The application protects thousands of virtual mechanisms by effortlessly applying amalgamated restoring projects operated from the vSphere Web Client and using policy-stimulated cybernation/ computerization and the SDDC building design to simplify continuous administration [5].

Up to 50% Lower TCO

Finally, the application lowers the general price of ownership of disaster restoration by up to 50 percent by lowering functional expenditures via autoimmunization and decrease of capital depositions utilizing SDDC technology [5].

Therefore, the dictum “server sprawl” has originated. In addition, the companies have to accept new power and cooling costs. Moreover, given the pace of growth, data center space appeared to be an infrequent commodity. In addition, racks were appointed at a violent pace at the time when organizations combated to sustain the demand. In fact, companies deployed servers, which did not operate at peak capacity and each new service added new spending in two ways. Firstly, each hardware device required innovative capital spending because of the requirement to substitute eventually that device. Secondly, the organization’s continuous operating budget has to be accommodated to obtain new cooling and power costs.


Virtualization frequently appears to be the Holy Grail of IT infrastructures. Nevertheless, it appears to have numerous advantages and disadvantages, which are vividly demonstrated in the current paper. The capacity to divide workloads into different containers while splitting hardware resources directly results in seriously enhanced hardware use. A virtualized infrastructure demonstrates that it is important to take care of distinct workloads with emulating requirements among discrepant hosts. It provides the possibility to equip decommission of different servers, leaving merely one in place. It provides fewer possibilities for hardware failures, decreased continuous power and cooling expenditures and lower incessant costs connected to server substitution.
This appears to be a win-win situation. The paper demonstrates that physical security implements are not created to secure virtual infrastructures, including virtualized data centers and private and hybrid clouds.

In fact, these “traditional” protection controls rely on physical implements and appliances developed on physical networks or on the perimeter of the data center. Therefore, the appropriate technology and operations demonstrate that virtualization has the possibility to make data centers even more compliant and protected unlike their physical elements.

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