Cloud Deployment Models

中文版：云部署模式

Cloud computing makes sharing of data dramatically simpler. There are three main deployment patterns of Cloud services.

Public Cloud

Services are provided over the Internet by third-party vendors.
Resources such as data storage are made available to the clients via the Internet.
Clients are allowed to use the services on a pay-as-you-go model, which significantly reduces the cost.
Advantages of public cloud are availability, reduced investment, and reduced maintenance as all the maintenance activities including hardware and software are performed by the cloud service providers.
Examples: Saving documents to the iCloud, Google Drive, and playing music from Amazon’s cloud player.

Also known as corporate cloud or internal cloud.
Owned exclusively by a single company with the control of maintaining its own data center.
The main purpose is not to sell the service to external customers but to acquire the benefits of cloud architecture.
Private clouds are comparatively more expensive than public clouds.
There are two variations:
- On-premise private cloud: internal cloud hosted within the data center of an organization. Provides more security but often with a limit on size and scalability. Data always resides in the local environment and is not taken care of by any third party. The enterprise bears all setup and maintaining costs.
- Externally hosted private cloud: hosted by external cloud service providers with full guarantee of privacy. Clients are provided with an exclusive cloud environment. The data and values reside with the third party and are not accessible during downtime. The cost includes setup and maintenance.

A combination of public and private clouds where the advantages of both types are clubbed.
Uses third-party cloud service providers either fully or partially.
Has at least one public cloud and one private cloud. Some resources are managed in-house and some are acquired from external sources.
The exact dividing line between public and private services varies case by case and is usually custom-tailored to meet the individual requirements of enterprise customers.