Cluster solutions on clusters and Linux

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Cluster System (Cluster) mainly solves the following problems:

High Reliability (HA)

With cluster management software, when the primary server fails, the backup server can automatically take over the work of the primary server and switch the past in time to realize the uninterrupted service to the users.

High-performance Computing (HP)

That is, to make full use of the resources of each computer in the cluster, to achieve parallel processing of complex operations, usually used in the field of scientific computing, such as genetic analysis, chemical analysis and so on.

Load Balancing

That is, load pressure is reasonably allocated to each computer in the cluster according to some algorithm to reduce the pressure on the primary server and reduce the hardware and software requirements for the primary server.

Linux based cluster solutions are blossoming. In practical applications, the most common scenario is to use clustering to solve load-balancing problems, such as providing WWW services. The main show here is how to use the LVs (Linux virtial Server) to implement a practical WWW load Balancing cluster system.

Introduction to the two LVS

LVS is the excellent cluster solution initiated and led by Dr. Zhangwensong, many commercial cluster products, such as Redhat's Piranha,turbolinux company's Turbo cluster, are based on the core code of LVS. In the practical application, LVS got a lot of deployment, please refer to http://www.linuxvirtualserver.org/deployment.html. For more detailed information on the working principle of Linux LVs, please refer to http://www.linuxvirtualserver.org.

Three LVS Configuration Example

The load balance of www,telnet service is realized through Linux LVS. The Telnet Cluster service is implemented here only for ease of testing.

LVS has three load balancing methods, NAT (receptacle address translation), DR (Direct Routing), IP tunneling. One of the most common is the Dr method, so here only describes the LVS load balancing of DR (Direct Routing) mode. For testing convenience, 4 machines are in the same network segment, connected by a switch or hub. In the practical application, it is best to VS1 the virtual server and the real server rs1, RS2 on different network segments, that is, improve the performance, and enhance the security of the whole cluster system.