Note for Cloud Computing - CC by pankhuri Aggarwal

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Chapter 1 Cloud computing:Cloud computing is is typically defined as a type of computing that relies on sharing computing resources rather than having local servers or personal devices to handle applications. In cloud computing, the word cloud (also phrased as "the cloud") is used as a metaphor for "the Internet," so the phrase cloud computing means "a type of Internet-based computing," where different services — such as servers, storage and applications — are delivered to an organization's computers and devices through the Internet. Cloud computing is comparable to grid computing, a type of computing where unused processing cycles of all computers in a network are harnesses to solve problems too intensive for any stand-alone machine. Why use clouds? Clouds can provide users with a number of different benefits. Many businesses large and small use cloud computing today either directly (e.g. Google or Amazon) or indirectly (e.g. Twitter) instead of traditional on-site alternatives. There are a number of reasons why cloud computing is so widely used among businesses today. - Reduction of costs – unlike on-site hosting the price of deploying applications in the cloud can be less due to lower hardware costs from more effective use of physical resources. - Universal access - cloud computing can allow remotely located employees to access applications and work via the internet. - Up to date software - a cloud provider will also be able to upgrade software keeping in mind feedback from previous software releases. - Choice of applications. This allows flexibility for cloud users to experiment and choose the best option for their needs. Cloud computing also allows a business to use, access and pay only for what they use, with a fast implementation time

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- Potential to be greener and more economical - the average amount of energy needed for a computational action carried out in the cloud is far less than the average amount for an on-site deployment. This is because different organisations can share the same physical resources securely, leading to more efficient use of the shared resources. - Flexibility – cloud computing allows users to switch applications easily and rapidly, using the one that suits their needs best. However, migrating data between applications can be an issue. How clouds are changing Cloud computing, software services, outsourcing and hosting mean very different things, but to IT managers and administrators, these technologies are all about the same thing: applications and/or data formerly on-premise are now on a server beyond the company perimeter. There is plenty of trepidation among established shops who are in a familiar (if not irritating) groove. How much disruption will this emerging computing model cause in the average enterprise? This special report digs into strategic areas of cloud computing where IT pros are short on answers. Key characteristics[change | change source] • • • Capital expenditure minimized, therefore low barrier to entry as infrastructure is owned by the provider and does not need to be purchased for one-time or infrequent intensive computing tasks. Services are typically being available to or specifically targeting retail consumers and small businesses. Device and location independence[28] which enables users to access systems regardless of location or what device they are using (for example PC, mobile,... etc.). Multitenancy enabling sharing of resources (and costs) among a large pool of users, allowing for: o Centralization of infrastructure in areas with lower costs (e.g. real estate, electricity) o Peak-load capacity increases (users need not engineer for highest possible load levels)

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Utilization and efficiency improvements for systems that are often only 10-20% utilised.[20] Performance is monitored and consistent but can be affected by insufficient bandwidth or high network load. Reliability by way of multiple redundant sites, which makes it suitable for business continuity and disaster recovery,[29] however IT and business managers are able to do little when an outage hits them.[30] Historical data on cloud outages is tracked in the Cloud Computing Incidents Database.[31] Scalability which meets changing user demands quickly, without having to engineer for peak loads. Massive scalability and large user bases are common but not an absolute requirement. Security which typically improves due to centralization of data, increased security-focused resources, etc. but which raises concerns about loss of control over certain sensitive data. Accesses are typically logged but accessing the audit logs themselves can be difficult or impossible. Sustainability through improved resource utilisation, more efficient systems and carbon neutrality.[32] o • • • • • Driving Factors Behind Cloud Computing Adoption If you're an IT manager or senior IT executive in the evaluation phase for turning over some of your infrastructure to the cloud, you’re not alone. Cloud adoption can vary by industry and organization, but cloud computing is rapidly making inroads into most organizations. According to a recent survey of 600 senior IT and business executives by Savvis, 70 percent of IT decision makers are using or plan to use cloud computing in their own enterprises within 24 months. While concerns about security, identity, SLAs, and other topics are still on the minds of many IT pros, those concerns are gradually being addressed by cloud providers. While cloud computing may not be a complete solution for every enterprise—nobody is talking about ditching internal data centers yet, and probably never will—a number of pressing factors are driving the growth of cloud computing. I’ll cover some of the biggest drivers towards cloud computing adoption here. Improved IT Agility As recently as a few years ago, it took far too long for many IT departments to respond to increasing demand for computing capacity. Too much paperwork, too many approvals, and a reliance on hardto-deploy physical servers meant that IT was often slow to respond to variable organizational needs. Virtualization helped that situation immensely, and the arrival of cloud computing gives IT

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organizations even more of an ability to easily (and cost-effectively) expand and reduce computing resources to meet fluctuating demands. Cost Savings and ROI Cloud computing isn’t a panacea, but there are clear-cut cases where moving part of your IT infrastructure to the cloud makes solid operational and financial sense. Here at Penton Media we recently moved from a cumbersome legacy email newsletter tool—developed in house— that required an ongoing (and expensive) commitment in terms of user training and application maintenance to a new cloud-based email newsletter solution. If you have legacy software applications in your own organization, are they really worth the time, expense, and human capital needed to keep them running when superior cloud-based alternatives are available? Private Cloud vs. Public Cloud The concept of the private cloud has gathered steam over the past 12 months. Public cloud computing services generally rely on having your data on someone else’s infrastructure. That can be a non-starter for many IT administrators, especially if your organization operates under tricky auditing, compliance, or data location requirements. That’s where the private cloud steps in: Leveraging virtualization and commodity hardware, the private cloud can provide some of the elastic benefits of public cloud computing without some of the inherent risks that public cloud computing still needs to address. Cloud-Savvy IT Staff A new breed of IT professionals is stepping into leadership positions in many organizations. Some fear that cloud computing could mean the end of their careers, but savvy IT pros realize that someone in the organization has to take the lead in selecting what IT platforms and services are moved to the cloud while simultaneously educating management and the rest of the organization why other elements aren’t good candidates for cloud computing treatment. Many organizations are eagerly recruiting skilled IT professionals who not only have a grasp of the technical aspects of in-house IT, but can also champion and facilitate the adoption of cloud computing products and services. I’ve heard firsthand that IT professionals who can simultaneously balance IT and tech needs while meeting the strategic needs of the business are a hot commodity, and business leaders should make every effort to retain and reward qualified staff and spend the necessary capital to train and reward the next generation of IT leadership. Jeff James is industry news analyst for Windows IT Pro. He was previously editor in chief of Microsoft TechNet magazine, was an editorial director at the LEGO Company, and has more than 15 years of experience as a technology writer and journalist. Comparison of Cloud computing with Grid computing Grid computing models on conglomeration and linkages of IT resources including network of disparate computers to form humongous IT infrastructure aimed to harness for computing in a collaborative fashion. A typical Grid Computing System normally comprises of computational grid and data grid. Cloud computing can be considered an extension of Grid computing. The Cloud computing characteristically has provision for on demand IT resource allocation and instantaneous scalability. Unlike