文档介绍：ABSTRACT
The puter technology has entered into the era work-centered, Web user numbers, application types, work flow increase exponentially; furthermore, different application has different flow puting requirements. The method that upgrades single server'puting capabilities only can't meet the humankind's needs more and more; the main problems are presented in the following aspects, such as upgrade plicacy, high cost and service discontinuity and the like. LVS (Linux Virtual server) cluster technology can meet work service's scalability, high availability, serviceability, price effectiveness needs. The basic principle to realize work service scalability for LVS is through the one-to-multiple mapping mechanism. Forwarding the service request to multiple nodes to execute, this mapping can be
realized in multiple-layers. Under the framework of LVS,the exchange technology in
the 4th layer-IPVS(IP Virtual Server) and KTCPVS (Kernel TCP Virtual Server) in the 7th layer are realized. The exchange in the 7th layer is also called content-oriented exchange technology. It can forward to respective server according to different customer request contents.
In mon Web applications, task has priority. The 4th layer oriented exchange
can't differentiate the tasks, which requests background servers to provide same service, Regardless of which server the request is being sent to, the return result should be same. But the exchange technology in the 7th layer balances the load, based on the contents. It provides a high-level control method for visiting flow. It executes the load-balancing decision by examining the data message in the application layer, and action according to the information in the message. It also can use the local features of the pletely- send similar requests to the identical server, which makes good similarity of
the requests, received at each background server. It can increase cache efficiency of each single server further; consequently it improves the system