cloud computing

Cloud computing Abstract:

Cloud computing is a highly scalable and cost-effective infrastructure for running HPC, enterprise and Web applications. However, the growing demand of Cloud infrastructure has drastically increased the energy consumption of data centers, which has become a critical issue. High energy consumption not only translates to high operational cost, which reduces the profit margin of Cloud providers, but also leads to high carbon emissions which is not environmentally friendly. Hence, energy-efficient solutions are required to minimize the impact of Cloud computing on the environment. In order to design such solutions, deep analysis of Cloud is required with respect to their power efficiency.

History of Cloud computing

History has a funny way of repeating itself, or so they say. But it may come as some surprise to find this old cliché applies just as much to the history of computers as to wars, revolutions, and kings and queens. For the last three decades, one trend in computing has been loud and clear: big, centralized, mainframe systems have been "out"; personalized, power-to-the-people, do-it-yourself PCs have been "in." Before personal computers took off in the early 1980s, if your company needed sales or payroll figures calculating in a hurry, you'd most likely have bought in "data-processing" services from another company, with its own expensive computer systems, that specialized in number crunching; these days, you can do the job just as easily on your desktop with off-the-shelf software. Or can you? In a striking throwback to the 1970s, many companies are finding, once again, that buying in computer services makes more business sense than do-it-yourself. This new trend is called cloud computing and, not surprisingly, it's linked to the Internet's inexorable rise. 

What is the cloud?

Cloud computing is a general term for the delivery of hosted services over the Internet. Cloud computing enables companies to consume compute resources as a utility -- just like electricity -- rather than having to build and maintain computing infrastructures in-house. 

Cloud computing promises several attractive benefits for businesses and end users. Three of the main benefits of cloud computing include:

• Self-service provisioning: End users can spin up computing resources for almost any type of workload on-demand.
• Elasticity: Companies can scale up as computing needs increase and then scale down again as demands decrease.
• Pay per use: Computing resources are measured at a granular level, allowing users to pay only for the resources and workloads they use.

Cloud computing services can be private, public or hybrid.

Private cloud services are delivered from a business' data center to internal users. This model offers versatility and convenience, while preserving management, control and security. Internal customers may or may not be billed for services through IT chargeback.

In the public cloud model, a third-party provider delivers the cloud service over the Internet. Public cloud services are sold on-demand, typically by the minute or the hour. Customers only pay for the CPU cycles, storage or bandwidth they consume. Leading public cloud providers include Amazon Web Services (AWS), Microsoft Azure, IBM/SoftLayer and Google Compute Engine.

Hybrid cloud is a combination of public cloud services and on-premises private cloud – with orchestration and automation between the two. Companies can run mission-critical workloads or sensitive applications on the private cloud while using the public cloud for bursty workloads that must scale on-demand. The goal of hybrid cloud is to create a unified, automated, scalable environment which takes advantage of all that a public cloud infrastructure can provide, while still maintaining control over mission-critical data.

Sharing and Storing Data

Cloud computing, in turn, refers to sharing resources, software, and information via a network, in this case the Internet. The information is stored on physical servers maintained and controlled by a cloud computing provider, such as Apple in regards to iCloud. As a user, you access your stored information on the cloud via the Internet.

By using cloud storage, you don’t have to store the information on your own hard drive. Instead, you can access it from any location and download it onto any device of your choice, including laptops, tablets, or smartphones. Moreover, you can also edit files, such as Word documents or PowerPoint presentations, simultaneously with other users, making it easier to work away from the office.

What makes cloud computing different?

It's managed

Most importantly, the service you use is provided by someone else and managed on your behalf. If you're using Google Documents, you don't have to worry about buying umpteen licenses for word-processing software or keeping them up-to-date. Nor do you have to worry about viruses that might affect your computer or about backing up the files you create. Google does all that for you. One basic principle of cloud computing is that you no longer need to worry how the service you're buying is provided: with Web-based services, you simply concentrate on whatever your job is and leave the problem of providing dependable computing to someone else.

It's "on-demand"

Cloud services are available on-demand and often bought on a "pay-as-you go" or subscription basis. So you typically buy cloud computing the same way you'd buy electricity, telephone services, or Internet access from a utility company. Sometimes cloud computing is free or paid-for in other ways (Hotmail is subsidized by advertising, for example). Just like electricity, you can buy as much or as little of a cloud computing service as you need from one day to the next. That's great if your needs vary unpredictably: it means you don't have to buy your own gigantic computer system and risk have it sitting there doing nothing.

It's public or private

Now we all have PCs on our desks, we're used to having complete control over our computer systems—and complete responsibility for them as well. Cloud computing changes all that. It comes in two basic flavors, public and private, which are the cloud equivalents of the Internet and Intranets. Web-based email and free services like the ones Google provides are the most familiar examples of public clouds. The world's biggest online retailer, Amazon, became the world's largest provider of public cloud computing in early 2006. When it found it was using only a fraction of its huge, global, computing power, it started renting out its spare capacity over the Net through a new entity called Amazon Web Services. Private cloud computing works in much the same way but you access the resources you use through secure network connections, much like an Intranet. Companies such as Amazon also let you use their publicly accessible cloud to make your own secure private cloud, known as a Virtual Private Cloud (VPC), using virtual private network (VPN) connections.

Types of cloud computing

IT people talk about three different kinds of cloud computing, where different services are being provided for you. Note that there's a certain amount of vagueness about how these things are defined and some overlap between them.

Infrastructure as a Service (IaaS) means you're buying access to raw computing hardware over the Net, such as servers or storage. Since you buy what you need and pay-as-you-go, this is often referred to as utility computing. Ordinary web hosting is a simple example of IaaS: you pay a monthly subscription or a per-megabyte/gigabyte fee to have a hosting company serve up files for your website from their servers.

Software as a Service (SaaS) means you use a complete application running on someone else's system. Web-based email and Google Documents are perhaps the best-known examples. Zoho is another well-known SaaS provider offering a variety of office applications online.

Platform as a Service (PaaS) means you develop applications using Web-based tools so they run on systems software and hardware provided by another company. So, for example, you might develop your own ecommerce website but have the whole thing, including the shopping cart, checkout, and payment mechanism running on a merchant's server. Force.com (from salesforce.com) and the Google App Engine are examples of PaaS.

What are the Advantages of Cloud Computing?

Worldwide Access. Cloud computing increases mobility, as you can access your documents from any device in any part of the world. For businesses, this means that employees can work from home or on business trips, without having to carry around documents. This increases productivity and allows faster exchange of information. Employees can also work on the same document without having to be in the same place.

More Storage. In the past, memory was limited by the particular device in question. If you ran out of memory, you would need a USB drive to backup your current device. Cloud computing provides increased storage, so you won’t have to worry about running out of space on your hard drive.

Easy Set-Up. You can set up a cloud computing service in a matter of minutes. Adjusting your individual settings, such as choosing a password or selecting which devices you want to connect to the network, is similarly simple. After that, you can immediately start using the resources, software, or information in question.

Automatic Updates. The cloud computing provider is responsible for making sure that updates are available – you just have to download them. This saves you time, and furthermore, you don’t need to be an expert to update your device; the cloud computing provider will automatically notify you and provide you with instructions.

Reduced Cost. Cloud computing is often inexpensive. The software is already installed online, so you won’t need to install it yourself. There are numerous cloud computing applications available for free, such as Dropbox, and increasing storage size and memory is affordable. If you need to pay for a cloud computing service, it is paid for incrementally on a monthly or yearly basis. By choosing a plan that has no contract, you can terminate your use of the services at any time; therefore, you only pay for the services when you need them.

What are the Disadvantages of Cloud Computing?

Security. When using a cloud computing service, you are essentially handing over your data to a third party. The fact that the entity, as well as users from all over the world, are accessing the same server can cause a security issue. Companies handling confidential information might be particularly concerned about using cloud computing, as data could possibly be harmed by viruses and other malware. That said, some servers like Google Cloud Connect come with customization spam filtering, email encryption, and SSL enforcement for secure HTTPS access, among other security measures.

Privacy. Cloud computing comes with the risk that unauthorized users might access your information. To protect against this happening, cloud computing services offer password protection and operate on secure servers with data encryption technology.

Loss of Control. Cloud computing entities control the users. This includes not only how much you have to pay to use the service, but also what information you can store, where you can access it from, and many other factors. You depend on the provider for updates and backups. If for some reason, their server ceases to operate, you run the risk of losing all your information
.

Internet Reliance. While Internet access is increasingly widespread, it is not available everywhere just yet. If the area that you are in doesn’t have Internet access, you won’t be able to open any of the documents you have stored in the cloud. 

Read more at http://www.moneycrashers.com/cloud-computing-basics/#thzo4EyIVWM78iUZ.99

Reference Site:

http://searchcloudcomputing.techtarget.com/definition/cloud-computing

http://www.moneycrashers.com/cloud-computing-basics/
http://www.explainthatstuff.com/cloud-computing-introduction.html