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A Virtualization Model for Cloud ComputingSouvik Pal1,Suneeta Mohanty2, P. K. Pattnaik3 and G.B.Mund4

Email: souvikpal22@gmail.com1,2,3,4KIIT University, Bhubaneswar, India

Email: {smohantyfcs@kiit.ac.in, patnaikprasantfcs@kiit.ac.in,mund@kiit.ac.in}

Abstract—Cloud Computing is now a very emerging field inthe IT industry as well as research field. The advancement ofCloud Computing came up due to fast-growing usage ofinternet among the people. Cloud Computing is basically on-demand network access to a collection of physical resourceswhich can be provisioned according to the need of cloud userunder the supervision of Cloud Service providerinteraction.From business prospective, the viable achievements of CloudComputing and recent developments in Grid computing havebrought the platform that has introduced virtualizationtechnology into the era of high performancecomputing.Virtualization technology is widely applied tomodern data center for cloud computing. Virtualization isused computer resources to imitate other computer resourcesor whole computers. This paper provides a Virtualizationmodel for cloud computing that may lead to faster access andbetter performance. This model may help to combine self-service capabilities and ready-to-use facilities for computingresources.

Index Terms—Cloud Computing, Virtual Machine,Virtualization, Hypervisor.

I. INTRODUCTION

Cloud Computing or Internet Computing is a model orinfrastructure that delivers applications as services over theInternet and also provides services that involve hardwareand system software in the data centers [1]. Cloud is a typeof distributed and parallel system comprising of a collectionof interconnected and virtualized computers which aredynamically provisioned and presented as one or more unifiedcomputing resources based on service-level agreement [2].For simplicity, A Cloud itself an infrastructure or frameworkthat comprises a pool of physical computing resources i.e. aset of hardware, processors, memory, storage, networks andbandwidth, which can be organized on Demand into servicesthat can grow or shrink in real-time scenario [3].

In this era of immense usage of internet throughout theglobe, virtualization technology is the key feature of CloudComputing. Virtualization technology creates an environmentthat enables on-demand and convenient network access to ashared collection of configurable physical resources (i.e. setof hardware, processors, memory, storage and bandwidth)and as well as helps the creation of individual VirtualMachines (VM) according to the need of the cloud user. Thispaper leads to a Virtualization model which elaborates theVirtualization layer, job deployment onto the VMs, and theinterconnection between cloud user, hypervisor and VirtualMachines.

A. Brief HistoryIn this era of rapidly growing usage of internet throughout

the world, Cloud Computing has become the icon of Internet-centric business place in the IT industry. The CloudComputing is not a totally new technology; it is basically ajourney through distributed, cluster and grid computing. Inthe case of cluster computing [4], many clusters were formed.A cluster is an aggregation of homogeneous computersinterlinked with each other by high-speed networks [5] andallocated in a centralized way.Sometimes, it is not feasible fora single computer to execute massive compute and dataintensive tasks. When a huge computational task is neededto execute, the individual computers may form a cluster toshare computational workload and they function as a singlevirtual machine. The advantage is that failure of a nodedoesn’t put any impact over the system because some anotherstandby node will do the needful task. But the drastic changesin the no. of service-oriented requests, lack of sufficientadditional resources, centralized resource handling are theissues of cluster computing. We need to discuss the updatingissues in Grid Computing [6].

Grid computing is the combination of computers fromvarious administrative domains to meet a common target andmay disappear after the completion of the task. It is analogousto power grid [7]. In an electrical grid scenario, there are threephases namely, Generation, Transmission and Distribution.But the users don’t need to know either the location of powerplant or the process by which users getting the power.Likewise, in grid computing, the end users do not know aboutthe underlying processes and resources. A massivecomputing task is assigned to a grid and the grid shares outthe task into sub tasks, which are independently consignedto a range of nodes. It’s all done by Job-scheduling Process[8]. Like cluster computing, Failure of a node doesn’t affectthe whole process. But it’s a different task to organize andmaintain heterogeneous systems. The grid resources incurunnecessary overheads in terms of stability. In compared tocluster and grid computing, clouds are highly scalable,capable of both centralized & distributed resource handling,loosely coupled and provide on-demand computation &application service. Cloud computing is basically known ascomputing over internet. Cloud computing is an enhancementof distributed and parallel computing, Cluster Computing andGrid computing. In this advanced era, not only user able touse a particular web based application but also that may bein active participation in its computational procedure by eitheradopting ,demanding or pay-per-use basis [9][10].

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B. Traditional versus Virtualization ApproachVirtualization is used computer resources to imitate other

computer resources or whole computers. A virtualizationenvironment that enables the configuration of systems (i.e.compute power, bandwidth and storage) as well as helps thecreation of individual Virtual Machine has become theessential technology of cloud computing environments.Virtualization provides a platform for optimizing complex ITresources in a scalablemanner (efficiently growing), which isideal for delivering services. At a fundamental level,virtualization technology enables the abstraction ordecoupling of the application payload from the underlyingphysical resource [2] that means Physical resources can bechanged or transformed into virtual or logical resources on-demand which is called Provisioning.

In traditional approach, there are mixed hardwareenvironment, multiple management tools, frequent applicationpatching and updating, complex workloads and multiplesoftware architecture. But comparatively in cloud data centerfar better approach like homogeneous environment,standardize management tools, minimal application patchingand updating, simple workloads and single standard softwarearchitecture [11].

The paper organized as follows:In the section 2, we have discussed the deployment models.Section 3 has given the idea of conventional cloud servicemodels. And in the section 4, we have given a proposedVirtualization mapping model.Section 5elaborates themapping approach &lastly, section 6 leads to future work.

II. CLOUD DEPLOYMENT MODELS

Depending on the requirement of services and theapplications, cloud models are categorized into four types[12]:

Public Cloud: Public cloud is an open cloud where thecomputer resources and same infrastructure used by multipleusers. Usable standardized workload for applications, highscalability, testing and developing applications, securitystrategy are the basic criterion of public cloud. Email-systemis a good example of public cloud. For example, when end-users use mail services say Yahoo or Gmail account, theyneed to have only a computer and internet connection. Userneed not to know about the underlying process. They arejust using the cloud. All the maintaining, testing anddeveloping task are done by Yahoo or Google itself.

Private Cloud: Private cloud is a particular organization-based Cloud where the computer resources and infrastructureare handled by an organization and highly virtualized data-center is located inside the client’s firewall. It has specificworkloads and provides well-managed environment,optimized usage of computing resources, security andcompliance. Quality of Service (QoS) is managed andcontrolled by the organization itself. For example, AmazonVirtual Private Cloud (VPC) is a private cloud, which offers

clients isolated AWS (Amazon Work Space) and protectionby Virtual Private Network (VPN) connections.

Hybrid Cloud: Combination of private cloud and publiccloud makes a hybrid cloud. The vendors use the physicalresources from public cloud on the basis of need of theclouduser and return the resources when it is of no use. Let usconsider a scenario: Suppose a company want to use a SaaSApplication, which would meet the considerations of thecompany, i.e. Security and standardize usage throughout thecompany. The SaaS provider creates a private cloud for theparticular company inside their firewall so that the entirecompany can use the cloud as a standard. Now they providethe company with a Virtual Private Network (VPN) for gettingmore security [13]. Hence, we can see that. Combining theadvantages of private and public cloud, we can create a hybridcloud.

Community cloud: In case of joint venture application, asame cloud infrastructure needs to be constructed and sharedby several organizations jointly, so that they can use thesame framework as well as policies, services, requirements,applications, and concerns [14]. Community cloud is highlyscalable and reduces cost complexity. The third-party vendoror any one of the vendors within the community may hostand maintain the community cloud infrastructure.

III. CLOUD SERVICE

End-users or clients use the cloud services according totheir needs. Cloud Service Providers (CSPs) deliver theservice on-demand basis. In this section, we are going todiscuss different types of services [12]providedby the CSPsas shown in the figure [1].

Resources as a Service (RaaS)[12]:At the bottom-mostlayer of the cloud service stack, there would be a collectionof physical Resources such asstorage, servers,bandwidth,data center space, and networks,which may beaccessed and shared by multiple CSPs. In the current scenario,resource virtualization is the key feature of Cloud computingand fast growth of hardware and computing resourcevirtualization facilitates the service providers for using RaaSservice when they are in need of the particular service. As forexample of RaaS, Amazon S3 may the best example.

Hypervisor Monitoring Environment (HME) [12] is like amiddleware, which persists in between IaaS and physicalresources (RaaS layer). The main functionality of this layer isto allocate the hardware resources and computing resourcesfrom the base-layer i.e. RaaS across multiple Virtual Machinesand to monitor the accesses of Virtual machines. We willelaborately discuss about this layer in the next section.

Infrastructure as a Service (IaaS): IaaS deals withinfrastructure on which RaaSmay get expanded itself due toresource virtualization. IaaSprovides virtualization technologywhich involves the provisioning of infrastructure to the cloudusers. Clients may rent infrastructure services rather thanbuying those servicesto reduce the cost complexity andresource virtualization may facilitate to get those services.Amazon EC2 is the common example of IaaS.

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Fig. 1. Cloud Service Model

Platform as a Service (PaaS):PaaS has the capability toprovide independent platform having deployment capabilitiesand it may be capable of executing multiple application onsingle platform concurrently. The user may be free to createhis applications which can be run over the service provider’sinfrastructure. Google Apps is the example of PaaS.

Software as a Service (SaaS): SaaS provides the platformfor software usage. Clients just use the software servicewithout the overhead of running, maintaining and updatingthe software. It helps to reduce the cost complexity becauseclients need not to be concerned about all those issues.Salesforce.com can be example of SaaS.

IV. PROPOSED VIRTUALIZATION MAPPING MODEL

In the paper, we have proposed an enhanced service modelwhich involves in mapping of Virtual machines onto the hostmachines. While accessing operating system, network, datastorage or software applications through the Internet fromthe service provider, cloud users have to send requestaccording to their needs and the hardware and computingresources are provisioned and VMs are mapped by thehypervisor administrator as shown in the figure [2].

A. Distributed Resources of Physical Hosts:At the base level of the cloud stack, there would be a

pool of resources of physical hosts in the distributed manner.Physical hosts is nothing but a collection of processors,memory, CPU Cores, storage which are provisioned to theuser and logically presented as a several numbers of VMsthrough the process of resource virtualization.

B. Hypervisor Monitoring Environment (HME):Over the physical hosts, there are Hypervisor Monitoring

Environment layer that consists of hypervisor, resourcevirtualization, VMs and hypervisor administrator. We have

considered a service scenario to increase theunderstandability of this particular layer. Suppose a clouduser needs an infrastructure-based service. While requestingfor infrastructure and resources, hypervisor is available fromthe booting time of the system to manage the allocation ofphysical and computing resources from the resource lateracross multiple VMs which would be mapped depending onthe availability of the physical hosts.

Hypervisor: Hypervisor is basically a mainframe operatingsystem which allows other operating systems to run on thesame system concurrently [12]. Accesses of VMs are controlsby the hypervisor. Hypervisors may be categorized in threetypes [13]:

Native Hypervisor: These types of hypervisor aredesigned to reside directly over the hardware platform forproviding better performance.

Embedded or Bare Metal Hypervisor:To get highperformance and to reduce the time complexity, embeddedhypervisors are integrated with processors on a separatechip.

Host Hypervisor: These kinds of hypervisors act asseparate software layer over both operating system andhardware to get improved performance.

Virtualization Layer:One of the most important layers ofcloud stack is Virtualization which mainly deals with network,storage and computation virtualization. The basic conceptof Virtualization is to hide underlying infrastructure by creatinga logical interface. Resources are virtualized and logicallyrepresented in this layer.

Network Virtualization: Network Virtualization involvesin implementing virtual networks within the physical serverfor switching between all the virtual servers instead of multi-pathed or multiplexed network channels by directly trunkingthem to WAN transport and multiple HBAs and NICs may beneeded for each application provided with a high speed singleEthernet connection [3].

Storage Virtualization: The key driver of storagevirtualization, storage networking and server virtualizationwas Fibre Channel (FC) and FC-based Storage Area Networks(FC-SAN) which facilitated storage connectivity (very highspeed) and storage solutions like point-to-point replicationand server-less back-up [3]. It also helps to optimize theperformance of the servers onwhich multiple applicationsare running and this technique has enabled numerousadvancements in the datacenter.

Computation Virtualization: Computation Virtualizationleads to virtualization of computing resources. Computingresources like server Virtualization and operating systemVirtualization has enabled the transformation from the server-centric traditional computing to network and Internet-centriccomputing. Operating system and server Virtualization createthe virtual (logical) servers which are free from constraints ofthe underlying physical location and physical infrastructureand the virtualization may facilitate to move the workloadsfrom source VM instance to target VM instance in real-timewhich is calledLive Migration [3][15].

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Fig. 2. Virtualization Model for Cloud Computing

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Virtual Machine (VM): Virtual Machines are like the interfaceto the user, which have own operating system (Guest OS)hosted by the host OS. Instead of interacting with a singlecomputer, Virtual Machines should have the capability tofacilitate the aggregation of system and computing resourcesfrom multiple machines and they should present a consistentand unified view to the users and the applications. The basicresponsibility of VMs would beto support multiple OS andapplication instances and to provide greater scalability andbetter performance.

Hypervisor Administrator:In a Cloud ComputingEnvironment, hypervisor administrator may have the mainresponsibility to control over the accesses of VMs. It shouldmonitor how the computing and system resources aredistributed and circulated for Virtualization and how Virtualmachines are mapped to the host machines so that the dataand computing resources can easily be retrieved from theresource pool by the CSPs or the cloud user. In the bootingtime of the system, hypervisor is accessible and hypervisoradministrator may regulate the allocation of system andcomputing resources and VMs are mapped to the hostmachine according to need of the user or theapplication.Hypervisor administrator should have thecapability to manage both the resources within the server(locally) and as well as the resources located in the otherservers connected to the network [3].

C. Platform Service:Platform service should have ability to create FCAPS-

oriented (Fault, Configuration, Account, Performance, andSecurity) virtual servers [3] which should allow to host theguest operating systems and to execute the user-applications.

Integration-Service Platform: This block can have theresponsibility to integrate the resources for multipleapplications and for the guest operating system. There wouldbe different kinds of guest operating systems; hence thisshould be platform independent.

Platform and OS Usage and Services: In that block,virtual servers may load and host the preferred choice ofoperating systems that allow the loading and executing theuser-application. In a cloud platform, application developerscreate and deploy applications and do not necessarily needto know the underlying resources or infrastructure.

Performance Measurements & UpdateConfiguration:Virtual servers can have the responsibility tomanage performance measurements, performanceoptimization, fault management and reliability and accounting.This block allows the service developers to make self-managed and self-configuring business workflows.

D. Software Service:This layer may provide ready-to-use software service and

the clients need not to take any overhead for buying andmaintaining the software [12]. Cloud users need not to knowthe underlying architectureof cloud infrastructure; they justuse and access the software. Basic blocks of software servicesmay facilitate the creation, delivery and usage of the softwares

which are discussed below [3]. Services Creation Platform: This block may provide

the tools which can be used for creation of applications.Applications are termed as collection of services and theycan be created and distributed over the virtual servers createdand controlled by the Platform service.

Services Delivery Platform: Services delivery platformcan necessarily defined as a workflow engine that should becapable of execution of the application and it should be ableto manage the orchestration of multiple distributable workflowelements.

Legacy Integration Services: This block may providethe services which can support integration of legacy or existingapplication. Support for inheritance or legacy of previousapplication is the key responsibility of that block.

E. Broker Service:Cloud brokers are like the agents between the virtual

environment and business service layer. The main goal ofthe cloud broker is to make optimal arrangement of virtualenvironment into CSPs which is configured and managed bythe service manager. In count to serving local requests, cloudbroker would have the responsibility for the federation ofremote sites [16]. Like the Virtualization layer, there arenetwork brokers, storage broker, and computation broker andthey have their each responsibility to look after theVirtualization respectively. They should be able to movethroughout the virtual environmentand also remote sites untilthe configuration and arrangement is satisfied. In addition,cloud brokers has

F. Business Service:Business service layer provides different aspects of

business controls and conditions like Business servicemanagement, Identity creation and validation, Authenticationand Access Control Management, Service level agreement,and Renewal service management.

Business Service Management:This block may help tomanage the service orchestration, service conditions, andprocess management. Service manager should be able toderive a collection of desired resources and their configuration,and also placement constraints according to licensing, cost,confidentiality etc. Process management has the authority toschedule and to manage the processes. Service manager hasalso the responsibility to monitor the deployed services andto adjust their capacity (number of VM instances).

Identity Creation and Validation:Creation of user-identity and its validation is the key responsibility of thisblock. When a new user comes up in the market, he needs tocreate his identity and this module may identify propervalidation for deployment of user-application.

Authentication and Access Control Management:Authentication should have the responsibility for effectivegovernance and proper management of their authenticatedprocess. Access control management service enables policiesand rules for access control in reply to a request from a clientwho is in need of resources and this block should also

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responsible for OS access control and network access control. Service Level Agreement (SLA):SLA management is

key aspect of Business Service. SLA is concerned aboutbusiness-aligned rule and policies. Distributed resources likenetwork, storage and network are provisioned but shouldnot be the cause of a SLA violation of any applicationexecuting with greater than predefined threshold line. Hence,service agreement should be maintained to keep the rules ofan organization.

Renewal Service Management:Renewal servicemanagement is responsible for renewal of policies, rules andaccess controls. Validation and updated SLAs should alsobe under the renewal service. This service basically a smoothinteracting medium for Internet-centric business place whereboth clients and CSPs could interact for their business andIT Infrastructure.

V. A MAPPING APPROACH

In this paper, we will discuss a mapping approach of VirtualMachines onto host machines depending on the availabilityof the distributed resources [17].We have defined our system as S where the set of Virtualmachines (V) are to be mapped onto the set of physical hostmachines (H); and pool of physical resources are denoted byP.P = {CPU cores, Memory, Storage, I/O, Bandwidth,Networking}.

According to the user-needs like IT infrastructure,platform service or software usage, VM instances are createdby the hypervisor administrator who controls the mappingof VMs.We have considered VS as Virtual Machine set:VS = V1 + V2 + …. + Vm = ViVi = { vc, vm, vr}Wherevc = Number of CPU Coresvm = Main Memoryvr = Storage Capacitym = Number of Virtual MachinesNow we considered HS as a Set of host machines:HS = H1+ H2 +…. + Hn= HiHi = {hc, hm, hr}Wherehc = Number of CPU Corehm = Main Memoryhr = Storage Capacityn = Number of host machines.Now we divide the host set into two subsets:HS = HSa + HSb ( a + b = n).

WhereHSa = Set of physical machines having available resources

to host VMs and on which VMs can be mapped.HSb = Set of remaining physical machines not having

enough resources to host VMs and on which VMs cannotbe mapped.Let f:Vi HSa be the Function which maps VM instance to

the set of physical machines having enough resources tohost the VM. There may be either one to one mapping ormany to one mapping. In one to one mapping, one VMinstance may be mapped onto one host machine and in manyto one mapping, many VM instances may be mapped ontoone host machine. Function f: Vi Hi describes theone to onemapping and function f: Vi Hi maps many to one mappingfrom the host set HSa based on the requirements and workloadof the use.In this way, VM instances may be mapped ontohost machine using the virtualization mapping diagram shownin the figure [2].

VI. FUTURE DIRECTION

Cloud mapping model may provide good and efficientquality services to the customers, in spite of that this modelhas constraints and that could be taken as future work. Ashypervisor administrator has the control over the access ofVMs and it controls the monitoring system, so crashing downthe hypervisor or the failure of the hypervisor or attacks onhypervisor administrator may lead to the performancedegradation. Dynamic mapping or run-time mappingaccording to the requirements of the user make the wholesystemslow. So better mapping technique can be developedfor fast access.Each organization has their own applicationinterface, services and policies. Hence, in a cloud platform, itis a mammoth task to maintain the heterogeneity of allorganization.

CONCLUSIONS

Rapid usage of Internet over the globe, Cloud Computinghas placed itself in every field of IT industry. To enhance ourmapping model, we may facilitate for the cloud users addingor removing at run-time. Our model for virtualizationincorporated some new phases to improve its capabilities. Itmay conclude that to facilitate maximum computation withminimal physical resources our mapping model helps to utilizethe resources efficiently.

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