While the term “cloud” is everywhere, few can pin down what it really means. The reason is that there are many flavors and components of cloud computing. According to the National Institute of Standards and Technology Information Technology (NIST) Laboratory, “Cloud computing is a model for enabling ubiquitous, convenient, on-demand network access to a shared pool of configurable computer resources (e.g., networks, servers, storage, applications, and services) that can be rapidly provisioned and released with minimal management effort or service provider interaction.” You can find the NIST's definition of cloud computing in their Special Publication 800-145 named "The NIST Definition of Cloud Computing."
Another way to think about it is that the cloud enables a user to expand and contract capacity and capabilities easily through self-service portals where catalogs enable simple configuration of the end service.
NIST identifies five essential characteristics of the cloud, summarized here:
On-demand self-service – A user can provision computing capabilities, such as server time and storage, as needed without requiring human interaction.
Broad network access – Capabilities are available over a network and typically accessed by the users’ mobile phones, tablets, laptops, and workstations.
Resource pooling – The provider’s computing resources are pooled to serve multiple users using a multi-tenant model, with different physical and virtual resources dynamically assigned and reassigned according to consumer demand. Examples of resources include storage, processing, memory, and network bandwidth.
Rapid elasticity – Capabilities can be elastically provisioned and released, in some cases automatically, to scale rapidly outward and inward as needed. For the user, the capabilities available for provisioning often appear to be unlimited and can be appropriated in any quantity at any time.
Measured service – Cloud systems automatically control and optimize resource use by leveraging a metering capability appropriate to the type of service (e.g., storage, processing, bandwidth, and active user accounts). Resource usage can be monitored, controlled, and reported, providing transparency for both the provider and user of the service. This cloud characteristic enables a cloud user to consume the service in a “pay as you grow” model or for internal IT departments to provide IT chargeback capabilities.
- Ryan Reed, Cloud Evangelist
Post Date: 30/06/2014