3/12/2013Computer Engg, IIT(BHU)1 CLOUD COMPUTING-1

What is cloud computing? Cloud computing is the scenario of distributed computing, that provides large amounts of computing and data storage capacity to its users with a promise of increased scalability, high availability, and reduced cost of maintenance and administration. Cloud computing is an on demand service in which shared resources, information, software and other devices are provided according to the clients requirement at specific time over the Internet. The whole Internet can be viewed as a cloud.

More about cloud It is simply plug and play mechanism of computing. The word “cloud computing” is not associated with any specific technology, protocol or vendor. The name cloud computing was inspired by the cloud symbol that’s often used to represent the Internet in flowchart and Diagrams. Previous computing trends were limited to specific user but Cloud computing aims to be global, it provides services ubiquitously and provides IT infrastructure to external datacenter. Computing capabilities are provided in virtual environment.

Key Characteristics On demand service Shared resources Measured services Flexibility Pay as you go Simple to use virtualization

On-demand self-service On-demand self service enables users to use cloud computing resources as needed without human interaction between the user and the provider. A consumer can schedule the use of cloud services such as computation and storage as needed in addition to managing and deploying these services. So this ease of use and elimination of human interaction provides efficiencies and cost savings to both users and cloud service providers.

Multi tenancy (shared resources) Cloud computing is based on a business model in which resources are shared (i.e., multiple users use the same resource) at the network level, host level, and application level. Unlike previous computing models, which assumed dedicated resources (i.e., computing facilities dedicated to a single user or owner).

Measured service The amount of cloud resources used by a consumer can be Monitored and billed automatically for usage of that particular session. Resource usage can be monitored, controlled, and reported by providing transparency for both the provider and consumer of the utilized service

Massive scalability Cloud facilitate its users massively scale bandwidth and storage space. Although organizations might have hundreds or thousands of systems, cloud computing provides the ability to scale to tens of thousands of systems, as well as the ability to massively scale bandwidth and storage space.

Flexibility Use of services can be ramped up and down based on demand. Users can rapidly increase and decrease their computing resources as needed, as well as release resources for other uses when they are no longer required

Pay as you go Users pay for only the resources they actually use and for only the time they require them.

Simple to use To avail the cloud services,its users to have only the internet connection with simple web browser containing Desktops or PCs.

Virtualization The ability to run multiple operating systems on a single physical system and share the underlying hardware resources. This features reduce the hardware and human resource cost. Applications are decoupled from the underlying hardware. Multiple applications can run on one computer (virtualization a la VMWare) or multiple computers can be used to run one application (grid computing).

Service models of Cloud The service models are as follows: Software as a Service (SaaS) Platform as a Service (PaaS) Infrastructure as a Service (IaaS)

Software as a Service (SaaS) The capability provided to the consumer is to use the provider’s application running on a cloud infrastructure. The applications are accessible from variant client devices through a client interface such as a web browser. The consumer does not manage or control the underlying cloud infrastructure. Examples: Salesforce.com, Google Apps.

Platform as a Service (PaaS) In a platform-as-a-service (PaaS) model, the vendor offers a development environment to application developers, who develop applications and offer those services through the provider’s platform. The provider typically develops toolkits and standards for development, and channels for distribution and payment Examples: force.com, Microsoft Azure, web and hosting

Infrastructure as a Service (IaaS) The capability provided to the consumer is to provision processing, storage, networks and other fundamental computing resources where the consumer is able to deploy and run arbitrary software, which can include operating system and application. Examples: Amazon EC2, Rackspace

The deployment models Private cloud Public cloud Hybrid cloud Community Cloud

Private cloud Generally private clouds are hosted by third parties rather than being hosted on dedicated servers. Private cloud is infrastructure operated solely for a single organization, whether managed internally or by a third-party and hosted internally or externally.

Public cloud A public cloud is hosted, operated, and managed by a third-party vendor from one or more datacenters. The service is offered to multiple customers (the cloud is offered to multiple tenants) over a common infrastructure

Hybrid cloud The term “Hybrid Cloud” has been used to mean either two separate clouds joined together (public, private, internal or external), or a combination of virtualized cloud server instances used together with real physical hardware. The most correct definition of the term “Hybrid Cloud” is probably the use of physical hardware and virtualized cloud server instances together to provide a single common service.

Community cloud Community cloud can be established where several organizations have similar requirements and seek to share infrastructure to realize some of the benefits of cloud computing. With the costs spread over fewer users than a public cloud (but more than a single tenant) this option is more expensive but may offer a higher level of privacy, security and/or policy compliance. Examples of community cloud include Google’s “Gov Cloud”.

Benefits of Cloud Computing Lower costs: The cost per unit of delivering service can be much lower for a larger provider. In addition, such providers can take advantage of lower real estate costs, lower power costs, etc. Better Service Levels: More reliable infrastructure, availability of skilled resources 24x7, etc., can allow cloud providers to deliver better services than a resource constrained internal IT shop Rapid Start Up: On demand services allow customers to gain nearly instant access to services, increasing speed to value Lower Start Up Costs: Customers don’t need to purchase, install, and test hardware and software.

Benefits Increased Utilization: Pay only for what is used. Shifting Cost Model: Costs are shifted from capital expenses to operational expenses Scalability: Use of services can be ramped up and down based on demand. IT doesn’t need to be built to handle peaks. Transparency of Costs: Usage can easily be metered and assigned back to users. Low Maintenance: Traditional, resource intensive maintenance activities are shifted to the provider.