原文链接：http://blog.csdn.net/blade2001/article/details/7194895
软件应用开发的经典模型有这样几个环境：开发环境(development)、集成环境(integration)、测试环境(testing)、QA验证，模拟环境(staging)、生产环境(production)。
通常一个web项目都需要一个staging环境，一来给客户做演示，二来可以作为production server的一个“预演”，正式发布新功能前能及早发现问题（特别是gem的依赖问题，环境问题等）。
From wiki: Staging site, in website design, is a website used to assemble, test and review its newer versions before it is moved into production. This phase follows the development phase. The staging phase of the software life-cycle is often tested on hardware that mirrors hardware used in the production environment. The staging site is often different from the development site, and provides a QA zone that is separate from the development or production environments.
Normally before deploying an updated version of software to the production environment, the update has been tested in the staging environment. The staging server will resemble the production environment where the clients can do the user acceptance testing activities. Tests on Staging server/site should be passed before deployment of system on live server, i.e. production environment.
staging server可以理解为production环境的镜像， QA在staging server上对新版本做最后一轮verification, 通过后才能deploy到产品线上. 有点网讯SERCM流程里面的SDA验证用的环境， 尽最大可能来模拟产品线上的环境(硬件，网络拓扑结构，数据库数据)
The staging environment consists of two components:
The staging database server.
The staging server.
Staging Database Server
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The staging database server contains the business data, such as marketing campaigns and product catalogs, and database resources that you want to stage to the database servers in the production environment.
Business users can update business data in the staging environment so that you can test and approve the changes before you incorporate the changes into the run-time environment. The staging environment prevents disruption of the run-time site and services by isolating the test and production systems.
Staging Server
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The staging server is a mirror of the production business management server.
You create staging projects and routes on the staging server to deploy site updates from the test environment to the production environment. You can also use the staging server to deploy updates to geographically distributed environments across a wide area network (WAN).
For example, business users and internal developers might update various aspects of the retail Web site at your headquarters in New York, where your test and production environments reside at the local data center. However, you might also maintain production environments in Seattle, Los Angeles, and Chicago. Therefore, you can use Commerce Server Staging (CSS) on the staging server to deploy local site updates to the production servers in other remote cities.