What is  Cloud?

As defined by the National Institute of Standards and Technology (NIST), “cloud is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources that can be rapidly provisioned and released with minimal management effort or service provider interaction.” (Microsoft, 2014)

Cloud computing is a pay-per-usage model. Cloud overcomes the traditional IT bottlenecks like the rooms full of data storage, firewalls and routers along with the teams to support it, when there were needs to invest in upgrades and rebills.

Figure 1 - Cloud computing (computing, 2014)

Deployment Models

History reveals a similar shift happened at the way business used power at the turn of the century. Business no longer has to build, buy or manage costly computing facility on site. Just as business learnt that power provided by a specialized power company improved reliable quality, cloud computing has proven to be more reliable, more secure, more scalable and ultimately more affordable than traditional onsite IT. This is why most new business apps and softwares are now deployed on cloud. Custom software companies in India has also started recommending cloud.

The following deployment models present a number of trade-offs in how customers can control their resources, and the scale, cost, and availability of resources.

1.      Private cloud: The cloud infrastructure is operated solely for an organization. It may be managed by the organization or a third party and may exist on premise or off premise.

2.      Community cloud: The cloud infrastructure is shared by several organizations and supports a specific community that has shared concerns (e.g., mission, security requirements, policy, and compliance considerations). It may be managed by the organizations or a third party and may exist on premise or off premise.

3.      Public cloud: The cloud infrastructure is made available to the general public or a large industry group and is owned by an organization selling cloud services.

4.      Hybrid cloud: The cloud infrastructure is a composition of two or more clouds (private, community, or public) that remain unique entities but that are bound together by standardized or proprietary technology enabling data and application portability.

5.      On-site private cloud: The security perimeter for this deployment model extends around both the subscriber's on-site resources and the private cloud's resources. The private cloud may be centralized at a single subscriber site or may be distributed over several subscriber sites. The subscriber implements the security perimeter, which will not guarantee control over the private cloud's resources, but will enable the subscriber to exercise control over resources entrusted to the on-site private cloud.