Introduction to Cloud computing cloud computing

Recently, many big companies such as MS, Google, IBM, etc. are hype a concept is cloud computing, such as IBM and the European Union to carry out cloud computing, the European Union grants 170 million euros; Google and IBM joined forces to push the cloud-computing model; Yahoo! also put it on cloud computing; China has also built a cloud computing hub in Wuxi with IBM; some say that a big consideration for Microsoft's acquisition of Yahoo! is that it's a bit of a point in Yahoo's leadership in cloud computing. So, what is cloud computing? I see a promotion of free and open source of the old gentleman to the cloud computing (Cloud Computing) translated into "cloud computing" is really ridiculous, many netizens are also asking what is cloud computing, what is the fog calculation, that many people for the cloud is confused. Cloud computing is not "sex", not Yunshan.

"Cloud computing" (Cloud Computing) is the development of distributed processing (distributed Computing), parallel processing (Parallel Computing) and Grid computing (grid Computing), or the business implementation of these computer science concepts. Many companies in the multinational information technology industry, such as IBM, Yahoo and Google, are using cloud computing to sell their products and services.

The term cloud computing may be borrowed from the "electronic cloud" in quantum physics (electron Cloud), highlighting the pervasive, ubiquitous, and socially characteristic of computing. Quantum physics has "electron cloud" (electron cloud), the electron moving around the nucleus is not an experienced world orbit, such as the celestial orbit, but the diffuse space, the cloud-like existence, describing the electron movement is not Newton classical mechanics but a probability distribution density function, The Schrodinger wave equation is used to describe the probability of a particle in a particular position in a given time, which is quite different from that of classical mechanics. The electronic cloud has the following characteristics, probability, diffuse, simultaneous, etc., cloud computing may indeed be from the concept of electronic cloud, the previous year has been called "ubiquitous computing", IBM has an ubiquitous computing called "ubiquitous", MS (Bill) soon followed by a ubiquitous calculation " Pervade ", now people have a new understanding of ubiquitous computing, now said to be" omnipresent. " But cloud computing is really not a purely commercial hype, it does change the pattern of the information industry, and now many people have used Google Docs and Google Apps to use many remote software applications such as Office word processing instead of installing these apps on their own local machines, Who's going to pay for office software in the future? There are many enterprise applications such as e-commerce applications, such as to write a transaction process, Google's corporate solution contains ready-made templates, a sales staff did not learn netbeanr can be done. This computing and industry trends are in line with the Open-source spirit and are consistent with SaaS (Software as a Service) trends. Now there is such a saying, there are only five computers in the world today, one is Google, one is IBM, one is Yahoo, one is Amazon, one is Microsoft, because these five companies take the lead in the distributed processing business applications to lead the trend. Sun has long argued that "networks are computers" is prescient.

The five main reasons why distributed computing is becoming more prevalent and evolving into mainstream computing patterns instead of centralized mainframe computers are as follows.

The first reason for the distributed system now is that he has a better performance-price ratio than a centralized system. You don't have to pay hundreds of thousands of dollars for efficient computing.

Most applications are distributed in their own right. such as industrial enterprise application, management department and the scene is not in the same place.

High reliability. Redundancy is not only a necessary condition for biological evolution, but also information technology. Modern distributed system has highly fault-tolerant mechanism, and the control reactor mainly uses distributed to achieve high reliability.

Scalability. Buying a higher-performance mainframe, or buying a mainframe with the same performance, is much more expensive than adding several PCs.

Highly flexible. Can be compatible with different hardware manufacturers, compatible with low configuration machines and peripherals to obtain high-performance computing.

Roughly calculated, the current personal computer CPU chip processing capacity of 200MIPS, is the implementation of 200M is 200 million times per second instruction, and recently Yahoo! company reported that they have achieved 10,000 nodes (node) is 10,000 PCs connected to the distributed system, The total processing capacity is 2,000,000mips, the fastest chip can not reach this speed, because the speed of the chip designed in a certain area is a limit, insurmountable. But the current world famous supercomputer so-called TOP500, achieves every second multi-trillion instruction execution, all is uses the distributed design, the world first IBM Bluegene supercomputer has adopted 32 racks, each frame deploys has 768 PowerPC440 CPU. By the way, this TOP500 basically uses the Linux operating system! Now the social and family-owned PC is the PC, and only 30% of the computing power is used, or even lower, while the remaining 70% is actually idle, These idle computer resources and computing capacity can be effectively used only through distributed systems, which greatly improve the computing capacity of a country, and the ability to compute is a measure of a country's national power and scientific research capacity, which is not yet fully recognized. The computing power of a country and region has now become an important strategic resource, no less than the importance of oil and other strategic goods. Cloud computing is the ability to connect ordinary servers or personal computers to get supercomputers, also called High-performance and high-availability computers, but at a lower cost. This is also an advanced project in the world. The cloud computing model can greatly improve the computer and commercial computing ability of our country, and make our country's economic competitiveness greatly improved. The United States and Europe have a wide range of distributed computing systems that mobilize and use these social computing capabilities for Human Genomics (genomics) research, astronomical problem studies, mathematical puzzle studies, and other scientific research issues. A study last year estimated that personal computer PCs in China were nearly 200 million.

According to the Guru Andrew S. Tanenbaum (AST) of the computer operating system, the definition of a distributed system is: "A distributed system is a system that runs on multiple machines without shared memory, but in the eyes of the user as a computer". (from "Modern operating system", Machinery Industry Press, 1999 Chinese edition). Its goal is to make each user feel that a networked computer is a time-sharing system-like using a personal computer-rather than a collective of many computers, even a five-node distributed system should make users feel like they're using a 200,000-dollar mainframe machine, The only unusual feeling is that the processing speed is much higher and nothing else is different. For example, here's a simple example when a user in machine a uses a file that is installed in the user's directory on machine B and a user logs on to the directory of machine b using telnet command rlogin B, then this is not a real distributed system, because user a realizes the existence of another machine, A distributed system must do that when user a logs on to a directory without knowing whether he is on the local machine or on a directory on a remote machine, and that machine B is transparent for user A, which is the "transparency" requirements considered in the design of distributed systems. Other related issues include: problems with Distributed file systems, directory and file access mechanisms, and consistency issues, communication problems with distributed system processes, and so on. The current cloud computing strictly says it has not reached the semantics level of true distributed computing.