Cloud computing synopsis and recommendations

Abstract

Cloud computing allows computer users to conveniently rent access to fully featured applications, to software development and deployment environments, and to computing infrastructure assets such as network-accessible data storage and processing.This document reprises the NIST-established definition of cloud computing, describes cloud computing benefits and open issues, presents an overview of major classes of cloud technology, and provides guidelines and recommendations on how organizations should consider the relative opportunities and risks of cloud computing.Cloud computing has been the subject of a great deal of commentary.Attempts to describe cloud computing in general terms, however, have been problematic because cloud computing is not a single kind of system, but instead spans a spectrum of underlying technologies, configuration possibilities, service models, and deployment models.This document describes cloud systems and discusses their strengths and weaknesses.Depending on an organization's requirements, different technologies and configurations are appropriate.To understand which part of the spectrum of cloud systems is most appropriate for a given need, an organization should consider how clouds can be deployed (deployment models), what kinds of services can be provided to customers (service models), the economic opportunities and risks of using cloud services (economic considerations), the technical characteristics of cloud services such as performance and reliability (operational characteristics), typical terms of service (service level agreements), and the security opportunities and risks (security).Deployment Models.A cloud computing system may be deployed privately or hosted on the premises of a cloud customer, may be shared among a limited number of trusted partners, may be hosted by a third party, or may be a publically accessible service, i.e., a public cloud.Depending on the kind of cloud deployment, the cloud may have limited private computing resources, or may have access to large quantities of remotely accessed resources.The different deployment models present a number of tradeoffs in how customers can control their resources, and the scale, cost, and availability of resources. Service Models.A cloud can provide access to software applications such as email or office productivity tools (the Software as a Service, or SaaS, service model), or can provide an environment for customers to use to build and operate their own software (the Platform as a Service, or PaaS, service model), or can provide network access to traditional computing resources such as processing power and storage (the Infrastructure as a Service, or IaaS, service model).The different service models have different strengths and are suitable for different customers and business objectives.Generally, interoperability and portability of customer workloads is more achievable in the IaaS service model because the building blocks of IaaS offerings are relatively well-defined, e.g., network protocols, CPU instruction sets, and legacy device interfaces. Economic Considerations.In outsourced and public deployment models, cloud computing provides convenient rental of computing resources: users pay service charges while using a service but need not pay large up-front acquisition costs to build a computing infrastructure.The reduction of up-front costs reduces the risks for pilot projects and experimental efforts, thus reducing a barrier to organizational flexibility, or agility.In outsourced and public deployment models, cloud computing also can provide elasticity, that is, the ability for customers to quickly request, receive, and later release as many resources as needed.By using an elastic cloud, customers may be able to avoid excessive costs from overprovisioning, i.e., building enough capacity for peak demand and then not using the capacity in non-peak periods.Whether or not cloud computing reduces overall costs for an organization depends on a careful analysis of all the costs of operation, compliance, and security, including costs to migrate to and, if necessary, migrate from a cloud.