Foreword
I had a reading notes before this chicken dish, arrange a "large-scale Web Site Technology Framework," a book five architectural elements described Zhihui teacher's book. These five factors are performance, availability, flexibility, scalability, security . In this paper, scalability simple discussion of the elements of the content is the main reference from "large-scale Web Site Technology Framework" This book (a very recommend this book, personally think that this book can be said to exist as the introduction of technology architecture ).
Scalability refers to the so-called site without changing the hardware and software design of the site, simply by changing the number of servers deployed can be enlarged or reduced service processing capabilities of the site.
Site architecture design flexibility
First, to achieve physical separation of different functions telescopic
Early development of the site, improve the site server by increasing the processing power, the new servers are always separated sub-features and services from an existing server. As follows
Second, the single function achieved by stretching cluster size
As the site describes the availability of infrastructure design, mention of the use of cluster server to avoid some of the pressure is too large, use the cluster is also an important means to achieve scalability.
Scalable design application server clusters
As long as the application server does not have a state , then they can easily pass through the load balancer to add new servers to the cluster.
Scalability Distributed cache cluster
Application servers in the cluster each server to deploy the same application!
The distributed cache server cluster in different servers cache data are different,
Renyiyitai cache access request can not be processed in the cache server cluster, you must first find the server that buffers data is needed before you can access.
This feature will seriously restrict design flexibility of distributed cache cluster, because the new on-line server does not cache any data cache, and the cache server has gone offline cache also many hot data site .
Must make a new on-line cache server with minimal impact on the whole distributed cache clusters, that is to say after the newly added cache server should make the entire cache server cluster cached data is also possible to access, which is scalable distributed cache clusters the main goal of the design.
Scalable design data storage server cluster
Scalability relational database by Sharding achieved, according to certain rules of data distributed to different nodes, so as to solve the storage space of a single storage server limits.