What is Cloud Computing

Dimension Data defines cloud computing as a style of computing in which IT resources are abstracted from the underlying infrastructure and provided on-demand and at scale in a multi-tenant environment.

Several definitions exist for cloud computing that are frequently referenced:

One analyst’s definition: a style of computing where scalable and elastic IT capabilities are provided as a service to multiple customers using Internet technologies

Another analyst’s definition: a standardized IT capability (services, software, or infrastructure) delivered via the Internet in a pay-per-use and self-service way

NIST definition: cloud computing is a model for enabling convenient, on-demand network access to a shared pool of configurable computing resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.

Regardless of the specific definition, cloud computing has the following characteristics:

  1. Pay-per-use
  2. Self-service
  3. Standardized
  4. Multi-tenant
  5. On-demand
  6. Abstracted
  7. Scalable
  8. Network-based
  9. Easy-to-use.

Several cloud types exist for cloud computing:

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.

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.

Hybrid cloud. The cloud infrastructure is a composition of two or more clouds (private, community, or public) that remain unique entities but are bound together by standardized or proprietary technology that enables data and application portability (e.g., cloud bursting for load-balancing between clouds).

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.

Several service models exist for cloud computing, including Software-as-a-Service (SaaS), Platform-as-a-Service (Paas), and Infrastructure-as-a-Service (IaaS).

SaaS (application): a hosted application accessed through a Web browser. SaaS alleviates the maintenance and technical operation and support of business and consumer software. The end-user does not manage or control the underlying cloud infrastructure including network, servers, operating systems, storage, or even individual application capabilities, with the possible exception of limited user-specific application configuration settings. SaaS is offered with a subscription instead of traditional software license.

PaaS (platform): an in-cloud platform for the development and deployment of application software. PaaS enables the creation of applications using programming languages and tools supported by the provider. PaaS offerings are designed to support the entire application development lifecycle. PaaS includes vendors that provide the entire stack of PaaS functionality and those that partner with third parties (i.e. hosting provider) for the infrastructure component. The end-user does not manage or control the underlying cloud infrastructure including network, servers, operating systems, or storage, but has control over the deployed applications and possibly application hosting environment configurations.

IaaS (infrastructure): virtual or physical hardware resources (e.g. compute, storage, network) offered as a service with heavy reliance on server virtualization. IaaS is provided using a shared, multi-tenant IT infrastructure (compute and storage) architecture through on-demand services. IaaS enables the end-user to provision servers, storage, networks, and other fundamental computing resources. End-users are able to deploy and run software, which can include operating systems and applications, on cloud-based servers. The end-user does not manage or control the underlying cloud infrastructure but has control over operating systems, data, deployed applications, and possibly limited control of select networking components (e.g., load balancing and firewalls).

Cloud computing services are hosted in data centers and are comprised of computer servers, storage and networking equipment, software and the people and processes that make it all work.

What is the difference between a virtualized data center and a cloud?

To create a true public or private cloud requires more than server virtualization. Public and private clouds must be self-service, scalable, controllable via a web console and API, and enable to provide reporting and billing for administration. The automation, orchestration and billing and metering software must be either developed or integrated by the client.

Dimension Data’s Public and Private Cloud offerings provide full automation, orchestration, administration, billing and metering support.