What is the cloud? First, a definition: Cloud computing is a model for enabling ubiquitous, 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. 1 When prominent computer scientists take several years and 15 drafts to arrive at a one-sentence definition, you can rely on it as an accurate yardstick. You can use it to measure not only your needs and the best ways to fulfill them but also the products and services your organization is considering for its move to the cloud. The closer your organization adheres to this definition, the more likely it will realize the benefits of the cloud, such as lower costs, faster deployment, lower power consumption and better service for internal and external customers. NIST has also set out a number of essential characteristics, deployment models and service models covered in the following pages that apply to true cloud computing. The NIST perspective sets expectations and describes the best ways organizations can profitably use the cloud. Although cloud computing continues to evolve, the definition of its characteristics and benefits is stable. 1 Peter Mell, Timothy Grance, “NIST Special Publication 800-145 — The NIST Definition of Cloud Computing,” September 2011, http://nvlpubs.nist.gov/nistpubs/Legacy/SP/nistspecialpublication800-145.pdf 3 ESSENTIAL CHARACTERISTICS OF THE CLOUD Typical cloud resources and capabilities include storage, processing, memory, network bandwidth and virtual machines. True cloud computing applies all of the following characteristics to those resources: • Broad network access — If you can’t get to it, you can’t use it. Cloud resources must be available in most reasonable places and users must be able to access them with standard, connected computing devices. • Rapid elasticity — One of the most appealing features of the cloud is the ability to use — and pay for — only the resources needed for only as long as needed. The ability to scale cloud resources up and down on short notice, or even automatically, is a far cry from the traditional, hardware-constrained IT model. • Resource pooling — Because cloud providers pool resources, users share them with other users. The exact physical resources matter little, varying as users’ needs scale up and down. Pooling and sharing are preferable to buying entire servers and using only a small fraction of their capacity. • On-demand — Users can provision resources now, without the need to wait weeks or months for a vendor to ship hardware. Storage, computing power, memory and other resources are available when and as you need them. • Self-service — Some providers make it as easy to use cloud resources as entering a credit card number. Self-service can eliminate the need to fill out paperwork, then wait for IT to rack and stack new equipment. • Measured — Cloud resource usage is continually metered so that Cloud computing means not having to pay for a large, resource-intensive server that you’re not using in its entirety. both provider and user can track consumption. That allows users to pay as they go for only the resources they use. With vendors and offerings that cover all of those bases, you will be more likely to realize the long-term promise of cloud computing. The absence of any one of those characteristics indicates a partial solution. 4