Cloud Computing Infrastructure

Cloud Computing Infrastructure

Cloud Computing Infrastructure (CCI) is a structured integration of physical as well as virtual resources which together create overall cloud environment and plays a crucial role in cloud service provisioning.

Cloud computing has emerged as a result of paradigm shift from local to network-centric computing and network-centric content, in which computing and storage resources are provided by distant data centers. Scientific and engineering applications, data mining, computational financing, gaming and social networking, and many other computational and data-intensive activities are getting benefitted from cloud computing. This vast domain of cloud applicability has been possible due to summing up of various key techniques, such as data storage technologies (like Google File System), Virtualization techniques, data management technologies (like Big Table), Distributing Computing as well as programming models and task scheduling models (like Map-Reduce) used in cloud computing. This integration of technologies has made the Cloud Infrastructure very huge in its dimension and complexity; and therefore it needs careful analysis to keep it resilient to a wide range of threats and vulnerabilities.

Infrastructure of a Cloud is comprised of the hardware and software components such as servers, storage, networking and virtualization software, which are bind together to support the computing requirements of a cloud computing model. Cloud computing infrastructure includes a software abstraction layer that virtualizes resources and logically presents them to users through programmatic means. In cloud computing, virtualized resources are hosted by a service provider or IT department and delivered to users over a network or the Internet. These resources include virtual machines and components such as servers, compute, memory, network switches, firewalls, load balancers and storage.

Cloud computing infrastructure can be visualized as a envelope that cover up each of the three cloud computing service models: infrastructure as a service (IaaS), platform as a service (PaaS) and software as a service (SaaS) within public, private and hybrid model. Together, these three service models form a cloud computing stack, with IaaS as the foundation, PaaS as the middle layer, and SaaS as the top layer. Figure 1 shows the layout of cloud computing infrastructure which is divided into three levels named as host level, network level and application level. All of these three levels are having different working patterns and different security features. Each level is dependent on other levels for communication and for providing services. 

Businesses or cloud service provider (CSPs) use cloud infrastructures to run their applications. Cloud infrastructures are typically purchased using a pay-per-use model. A cloud infrastructure provider is like a company that offers some component of cloud computing such as IaaS, SaaS or PaaS to other businesses or individuals. There are many companies which provide basic different services of cloud, Amazon (AWS) and Rackspace provides only IaaS for public, private and hybrid model. Windows azure and WorkXpress give their services only for PaaS. All these companies are not providing all services on a single platform, they are having their service infrastructure at different places and they treat a single service like an infrastructure.
A cloud thus not necessarily be confined to a small geographic location; but as the case of most CSPs like Amazon, Cloud infrastructure is built around Regions and Availability Zones, consisting of one or more discrete data centers, each with redundant power, networking and connectivity, housed in separate facilities. This geographically distributed nature of cloud along with abrupt migration of Virtual machines (VMs) between various physical host- locations increases the complexity of Cloud computing Infrastructure (CCI) many folds.
For any complicated system with a massive infrastructure, the most strenuous task is to keep it resilient towards all possible threats and vulnerabilities. This is why security and data privacy are still continuing to be key considerations in the evaluation and selection of cloud platforms. It makes organizations to have an immense focus on cloud Infrastructure‟s security aspects and design & implement a robust and easily configurable security architecture. 
Infrastructure is defined as „the basic physical and organizational structures and facilities (e.g. buildings, roads, power supplies, communication system) which are necessary for the operation of a society, system or any enterprise". Similarly Cloud Computing Infrastructure (CCI) is a structured integration of physical as well as virtual resources which together create overall Cloud environment; including servers, data storage and network components. 

Cloud Computing Infrastructure (CCI) consists of a wide range of cloud components such as processing elements, data centers, storage devices, networking, service level agreement(SLA) constraints, web based applications, cloud management software, deployment software, and platform virtualization.