An Overview on Important Aspects of Cloud Computing

An Overview on Important Aspects of Cloud Computing 1 Masthan Patnaik, 2 Ruksana Begum 1 Asst. Professor, 2 Final M Tech Student 1,2 Dept of Computer Science and Engineering 1,2 Laxminarayan Institute of Technology, Nagpur Abstract: Cloud computing as an emerging computing style and business paradigm will reshape commercial computing as a revolution. Cloud computing is a highly scalable and costeffective infrastructure for running HPC, enterprise and Web applications. Assigning the computing around great number of distributed computers, rather than local computer or remote computer is the basic principle of cloud computing. People can share distributed resources and services that belong to various organizations. Users without professional knowledge in this field and know nothing about the power to control it can enjoy the service. In this paper, we discuss about different aspects of cloud computing like types of clouds, deployment model of cloud based on its usage and characteristics of cloud. Here, we mainly specify the concrete and specific capabilities associated with clouds that are considered essential and relevant. We can thereby distinguish non-functional, economic and technological capabilities addressed, I INTRODUCTION With the growth of high speed networks over the last decades, there is an alarming rise in its usage comprised of thousands of concurrent e- commerce transactions and millions of Web queries a day. Many internet companies such as Google, Amazon, ebay, and Yahoo are operating such huge datacenters around the world. The commercialization of these developments is defined currently as Cloud computing, where computing is delivered as utility on a pay-asyou-go basis. Traditionally, business organizations used to invest huge amount of capital and time in acquisition and maintenance of computational resources. The emergence of Cloud computing is rapidly changing this ownership-based approach to subscriptionoriented approach by providing access to scalable infrastructure and services on-demand. Users can store, access, and share any amount of information in Cloud. That is, small or medium enterprises/organizations do not have to worry about purchasing, configuring, administering, and maintaining their own computing infrastructure. They can focus on sharpening their core competencies by exploiting a number of Cloud computing benefits such as on-demand computing resources, faster and cheaper software development capabilities at low cost. Cloud Computing is a distributed computing paradigm that mixes aspects of Grid Computing, Internet Computing, Utility Computing, Autonomic Computing and Green Computing. Cloud comes from the service-centric perspective that is widely spreading in the World of IT. From this perspective, all capabilities and resources of a cloud are provided to users as a service to be accessed through the internet without any specific knowledge of, expertise with, or control over the underlying technology infrastructure supporting them. It offers a usercentric interface that acts as a unique, user friendly, point of access for user s needs and requirements. It is a Pay-per-Use-on-Demand mode; users can buy access and share the computing resources through internet according to their own needs. User would be benefited and save the cost to buy the physical resources. Where the resources include network, server, storage, application, service and so on. People can dynamically lease physical or virtual resources. All the resources on cloud can be quickly and elastically deployed. The availability of resources can much improved by cloud computing. Science & Engineering 164

In this paper, we discuss about different aspects of cloud computing like types of clouds, deployment model of cloud based on its usage and characteristics of cloud. Here, we mainly specify the concrete and specific capabilities associated with clouds that are considered essential and relevant. We can thereby distinguish non-functional, economic and technological capabilities addressed, Non-functional aspects represent qualities or properties of a system, rather than specific technological requirements. Economical aspects particular interest is typically lies in the reduction of cost and effort through outsourcing and / or automation of essential resource management. Obviously, technological challenges implicitly arise from the nonfunctional and economical aspects, when trying to realize them. II TYPES OF CLOUDS Cloud providers typically centre on one type of cloud functionality provisioning: Infrastructure, Platform or Software / Application. Mainly there are three types of clouds. They are: Infrastructure as a Service (IaaS) also referred to as Resource Clouds, provide resources as services to the user in other words, they basically provide enhanced virtualisation capabilities. Accordingly, different resources may be provided via a service interface: Data & Storage Clouds deal with reliable access to data of potentially dynamic size, weighing resource usage with access requirements and / or quality definition. Platform as a Service (PaaS), provide computational resources via a platform upon which applications and services can be developed and hosted. PaaS typically makes use of dedicated APIs to control the behaviour of a server hosting engine which executes and replicates the execution according to user requests (e.g. access rate). As each provider exposes his / her own API according to the respective key capabilities, applications developed for one specific cloud provider cannot be moved to another cloud host. Software as a Service (SaaS), also sometimes referred to as Service or Application Clouds are offering implementations of specific business functions and business processes that are provided with specific cloud capabilities, i.e. they provide applications / services using a cloud infrastructure or platform, rather than providing cloud features themselves. III Cloud Computing Deployment Models Similar to P/I/SaaS, clouds may be hosted and employed in different fashions, depending on the use case, respectively the business model of the provider. So far, there has been a tendency of clouds to evolve from private, internal solutions (private clouds) to manage the local infrastructure and the amount of requests e.g. to ensure availability of highly requested data. Therefore, the Cloud deployments are classified mainly into three types: Public Cloud, Private Cloud and Hybrid Cloud. A) Public Clouds Public Cloud is the most common deployment model where services are available to anyone on Internet. To support thousand of public domain users, datacenters built by public Cloud providers are quite large comprising of thousands of servers with high speed network. Some of the famous public Clouds are Amazon Web Services (AWS), Google AppEngine, and Microsoft Azure. In this deployment, Cloud services are made available to the public in a pay-as-you-go-manner. A public Cloud can offer any of the three kinds of services: IaaS, PaaS, and SaaS. The fundamental characteristic of public Clouds is its multi-tenancy, which is essentially achieved using sophisticated virtualization at various level of the software stack. Being public Clouds, Quality of Service and security are the main issues that need to be ensured in their management. Thus, a significant portion of the software infrastructure is devoted to monitor Cloud resources, to bill them according to the contract made with the user, and to keep a complete history of the Cloud usage for each customer. Science & Engineering 165

Hybrid Clouds is the deployment which emerged due to diffusion of both public and Private Clouds advantages. In this model, organizations outsource non-critical information and processing to the public Cloud, while keeping critical services and data in their control. Therefore, organizations can utilize their existing IT infrastructure for maintaining sensitive information within the premises, and whenever require auto-scaling their resources using public Clouds. These resources or services are temporarily leased in peak load times and then released. The hybrid Cloud, in general, applies to services related to IT infrastructure rather than software services. Figure 2. Deployment Models for Clouds B) Private Clouds While public Clouds are quite appealing and provide a viable solution for cutting IT costs such as administration and infrastructure, there are still many scenarios where organization may want to maintain their own specialized Clouds catering to their particular needs. For instance, the health care industry maintains many confidential medical data which cannot be stored in public infrastructure. Thus, private Clouds are deployed within the premise of an organization to provide IT services to its internal users. The private Cloud services offer greater control over the infrastructure, improving security and service resilience because its access is restricted to one or few organizations. Such private deployment poses an inherent limitation to end user applications i.e. inability to scale elastically on demand as can be done using pubic Cloud services. An organization can buy more machines according to expanding needs of its users, but this cannot be done as fast and seamlessly as with public Clouds. This resulted in the emergence of hybrid deployments for Clouds where the advantages of both private and public Clouds are made available to the organization. C) Hybrid Clouds IV CAPABILITIES OF CLOUD In this section we specify the concrete capabilities associated with clouds that are considered essential (required in any cloud environment) and relevant (ideally supported, but may be restricted to specific use cases). We can thereby distinguish non-functional, economic and technological capabilities addressed, respectively to be addressed by cloud systems. A)NON-FUNCTIONAL ASPECTS The most important non-functional aspects are: Elasticity is an essential core feature of cloud systems and circumscribes the capability of the underlying infrastructure to adapt to changing, potentially non-functional requirements, for example amount and size of data supported by an application, number of concurrent users etc. Reliability is essential for all cloud systems in order to support today s data centre-type applications in a cloud, reliability is considered one of the main features to exploit cloud capabilities. Reliability denotes the capability to ensure constant operation of the system without disruption, i.e. no loss of data, no code reset during execution etc. Reliability is typically achieved through redundant resource utilisation. Quality of Service support is a relevant capability that is essential in many use cases where specific requirements have to be met by the outsourced services and / or resources. In business cases, basic Quos metrics like response time, throughput etc. Science & Engineering 166

must be guaranteed at least, so as to ensure that the quality guarantees of the cloud user are met. Agility and adaptability are essential features of cloud systems that strongly relate to the elastic capabilities. It includes on-time reaction to changes in the amount of requests and size of resources, but also adaptation to changes in the environmental conditions that e.g. require different types of resources, different quality or different routes, etc. Implicitly, agility and adaptability require resources (or at least their management) to be autonomic and have to enable them to provide self capabilities. A) ECONOMIC ASPECTS In order to allow for economic considerations, cloud systems should help in realising the following aspects: Cost reduction is one of the first concerns to build up a cloud system that can adapt to changing consumer behaviour and reduce cost for infrastructure maintenance and acquisition. Scalability and Pay per Use are essential aspects of this issue. Pay per use: The capability to build up cost according to the actual consumption of resources is a relevant feature of cloud systems. Pay per use strongly relates to quality of service support, where specific requirements to be met by the system and hence to be paid for can be specified. Going Green is relevant not only to reduce additional costs of energy consumption, but also to reduce the carbon footprint. Whilst carbon emission by individual machines can be quite well estimated, this information is actually taken little into consideration when scaling systems up. Clouds principally allow reducing the consumption of unused resources (downscaling). In addition, up-scaling should be carefully balanced not only with cost, but also carbon emission issues. B) TECHNOLOGICAL ASPECTS The main technological challenges that can be identified and that are commonly associated with cloud systems are: Virtualisation is an essential technological characteristic of clouds which hides the technological complexity from the user and enables enhanced flexibility (through aggregation, routing and translation). More concretely, virtualisation supports the following features: Ease of use: through hiding the complexity of the infrastructure (including management, configuration etc.) virtualisation can make it easier for the user to develop new applications, as well as reduces the overhead for controlling the system. Infrastructure independency: in principle, virtualisation allows for higher interoperability by making the code platform independent. Flexibility and Adaptability: by exposing a virtual execution environment, the underlying infrastructure can change more flexible according to different conditions and requirements (assigning more resources, etc.). Multi-tenancy is a highly essential issue in cloud systems, where the location of code and / or data is principally unknown and the same resource may be assigned to multiple users (potentially at the same time). This affects infrastructure resources as well as data / applications / services that are hosted on shared resources but need to be made available in multiple isolated instances. Classically, all information is maintained in separate databases or tables, yet in more complicated cases information may be concurrently altered, even though maintained for isolated tenants. Data Management is an essential aspect in particular for storage clouds, where data is flexibly distributed across multiple resources. Implicitly, data consistency needs to be maintained over a wide distribution of replicated data sources. At the same time, the system always needs to be aware of the data location (when replicating across data centres) taking latencies and particularly workload into consideration. As size of data may change at any time, data management addresses both horizontal and vertical aspects of scalability. APIs and / or Programming Enhancements are essential to exploit the cloud features: common programming models require that the developer takes care of the scalability and autonomic capabilities him- / herself, whilst a cloud environment provides the features in a fashion that allows the user to leave such management to the system. Science & Engineering 167

V CONCLUSION The increasing availability of high-speed Internet and corporate IP connections is enabling the delivery of new network-based services. Cloud computing potentially offers an overall financial benefit, in that end users share a large, centrally managed pool of storage and computing resources, rather than owning and managing their own systems. Cloud computing is a powerful new abstraction for large scale data processing systems which is scalable, reliable and available. In this paper, we discuss about different aspects of cloud computing like types of clouds, deployment model of cloud based on its usage and characteristics of cloud. Here, we mainly specify the concrete and specific capabilities associated with clouds that are considered essential and relevant. We can thereby distinguish non-functional, economic and technological capabilities addressed, Cloud computing promises many benefits, including reduced cost, increased storage, high degree of automation, flexibility, mobility. IEEE CS Press, Sept. 25 27, 2008, Dalian, China. [4] The Open Group, Service Oriented Infrastructure Reference Framework, http://www.opengroup.org/projects/soasoi/ uploads/40/19218/soi-v1-5-p1.pdf, 2009 [5] Khanvilkar, S., Khokhar, A., "Virtual Private Networks: An Overview with Performance Evaluation", IEEE Communication magazine, vol. 42 (10), pp. 146-154, October 2004 [6] J. Li, D. Agarwal, M. Humphrey, C. van Ingen, K. Jackson, And Y. Ryu. EScience in the Cloud: A MODIS Satellite Data Reprojection and Reduction Pipeline in the Windows Azure Platform. In Proceedings of the 24th IEEE International Parallel and Distributed Processing Symposium (IPDPS 2010), Atlanta, GA, April 19-23, 2010. [7] M. Armbrust, A. Fox, R. Griffith, A. Joseph, R. Katz, A. Konwinski, G. Lee, D. Patterson, A. Rabkin, I. Stoica et al., A View of cloud computing, Communications of the ACM, vol. 53, No. 4, pp. 50 58, 2010. VI REFERENCES [1] M. Armbrust, A. Fox, R. Griffith, A. Joseph, R. Katz, A. Konwinski, G. Lee, D. Patterson, A. Rabkin, I. Stoica, M. Zaharia. Above the Clouds: A Berkeley View of Cloud computing. Technical Report No. UCB/EECS-2009-28, University of California at Berkley, USA, Feb. 10, 2009. [2] R. Buyya, C. S. Yeo, S. Venugopal, J. Broberg, and I. Brandic. Cloud Computing and Emerging IT Platforms: Vision, Hype, and Reality for Delivering Computing as the 5th Utility, Future Generation Computer Systems, vol. 25, no. 6, June 2009, pp 599 616, Elsevier Science, Amsterdam, the Netherlands. [3] R. Buyya, C.S. Yeo, and S. Venugopal, Market-Oriented Cloud Computing: Vision, Hype, and Reality for Delivering IT Services As Computing Utilities, Keynote Paper, in Proc. 10th IEEE International Conference on High Performance Computing and Communications (HPCC 2008), Science & Engineering 168