Cloud computing

Cloud computing refers to accessing computing resources that are typically owned and operated by a third-party provider on a consolidated basis in data center locations. It is aimed at delivering cost-effective computing power over the Internet, typically for high-transaction-volume applications rather than those requiring extreme computational power. Consumers of cloud computing services purchase computing capacity on-demand and are not generally concerned with the underlying technologies used to achieve the increase in server capability.

There is no single industry-accepted definition. Some services broker extra capacity available on enterprise servers, as well as resources in pools of managed virtual servers. Others sell capacity on virtual servers. Yet others include any external computing resource, even to outsourced backup services, within the definition.

The applications of cloud/utility computing models are expanding rapidly as connectivity costs fall, and as computing hardware becomes more efficient at operating at scale. The economic incentives to share hardware among multiple users are increasing; the drawbacks in performance and interactive response that used to discourage remote and distributed computing solutions are being greatly reduced. As a result, the services that can be delivered from the cloud have expanded past web applications to include storage, raw computing, or access to any number of specialized services.

How cloud computing works

does that by networking large groups of servers that often use low-cost consumer PC technology, with specialized connections to spread data-processing chores across them. The architecture behind cloud computing is a massive network of "cloud servers" interconnected as if in a grid running in parallel, sometimes using the technique of virtualization to maximize the utilization of the computing power available per server.

Advantages

• Location of infrastructure in areas with lower costs of real estate and electricity.
• Sharing of peak-load capacity among a large pool of users, improving overall utilization.
• Separation of infrastructure maintenance duties from domain-specific application development.
• Separation of application code from physical resources.
• Ability to use external assets to handle peak loads (not having to engineer for highest possible load levels).
• Not having to purchase assets for one-time or infrequent intensive computing tasks.
• Ability to scale to meet changing user demands quickly, usually within minutes

Challenges facing cloud computing

The technical standards for connecting the various computer systems and pieces of software needed to make cloud computing work still aren't completely defined. That could slow progress on new products. Without high-speed connections—especially wireless ones—cloud computing services won't be widely accessible. And storing large amounts of data about users' identity and preferences is likely to raise new concerns about privacy protection.

Cloud storage

Cloud storage is a model of networked data storage where data is stored on multiple virtual servers, generally hosted by third parties, rather than being hosted on dedicated servers. Hosting companies operate large data centers; and people who require their data to be hosted buy or lease storage capacity from them and use it for their storage needs. The data center operators, in the background, virtualize the resources according to the requirements of the customer and expose them as virtual servers, which the customers can themselves manage. Physically, the resource may span across multiple servers. In some services, such as Nirvanix, the system may span multiple data centers or even continents.

Examples

• IBM’s Blue cloud
• Amazon Elastic Compute Cloud
• Microsoft Live Mesh
• Apple Mobile Me