Time: 2.5 hours
Neal Leavitt, "Is Cloud Computing Really Ready for Prime Time?," Computer, vol. 42, no. 1, pp. 15-20, Jan. 2009, doi:10.1109/MC.2009.20

以下是文章摘录

1. 业界人士对Cloud Computing的看法

"The shift to cloud computing will dramatically reduce the cost of information technology. But it goes beyond cost savings. It frees customers from the expense and hassle of having to install and maintain applications locally." (Russ Daniels, HP vice president & CTO for cloud-service strategy)

"Cloud computing also lowers the cost of application development and makes the process more scalable." (Simon Heron, Network Box)

"Key risks include reliability, security, the additional cost of the necessary network bandwidth, and getting locked into specific cloud computing vendors." (Carl Howe, director of the Anywehre Consumer Research Group for the Yankee Group)

2. Cloud Computing的前驱技术
(1) thin clients: 客户端
(2) grid computing: 服务器端
(3) utility computing: 计价模式

3. 与Cloud有关的一些公司
(1) 主要的Cloud Provider: Amazon, Google Apps, Salesforce.com's Force.com, MS's Azure
(2) 其他的Cloud Provider: AppNexus, GoGrid, GridLayer, Mosso, Xcalibre Communications
(3) 其他Cloud相关的公司: Cisco, Oracle, HP, IBM, Sun

4. 云计算的Advantages
"Most enterprise data centers are using less than 50 percent of the total capacity of their resources." (Staten, Forrester)
(1) Availability
要提高Availability, 通常需要冗余的资源来实现, 但这同时又会造成资源空置. 对于中小型公司来说, 代价过于昂贵. 如果采用云计算, 可以以较低的代价取得较高的availability.
(2) Application integration and support
"Integrating multiple services and assets into a powerful composite application is more convenient with well-designed cloud platforms." (Peter Coffee, Salesforce.com)
这里涉及到一点服务组合的概念了.
(3) Flexibility
资源可以按需使用. 如果不用云计算, 服务器要按照最高workloads的量来配置, 这样会造成资源利用率低.

5. 企业界对Cloud Computing的接受程度
   最早接受云计算的是Web2.0公司和刚开始创业的公司. 云计算按需使用的特点可以使此类公司降低成本.
   大公司对于新技术一向都比较迟疑, 通常要等比较成熟时才会大量采用.

6. 云计算面临的Challenges
(1) Control
这里是指对platform的control, 云计算的平台是外部提供的, 本公司不具有控制权.
(2) Performance, latency, reliability
transaction-oriented and data-intensive application比较关注性能问题.
分配了太多的虚拟机, 网络链接不好或客户所在地离云计算中心太远都会影响性能.
(3) Security & Privacy
IDC最近的一份调查显示, 客户在考虑云计算时, Security是最大的关注点.
几乎所有的公司对于把公司的数据存放到外部会心存疑虑, 金融公司对于这个更加敏感. 此外, 有些国家的法规对与公司数据存放地点也有规定.
(4) Related bandwidth costs
对于data-intensive应用, 网络费用可能会很高
(5) Vendor lock-in and standards
云计算的Vendor使用的技术是专有的, 互相之间portability/interoperability比较差
(6) Transparency
"Who has access to their data? how they keep unauthorized personnel from retrieving information?"
(7) Reliability
Salesforce.com和Amazon S3, EC2在2008年2月均发生过停机事故.
(8) Other concerns
有些infrastructure本质上就是不适合使用云计算来实现, 比如high-end databases (调查: 哪些类型应用适合云计算, 哪些不适合?)