Research And Implementation Of The Key Technologies Of The Server Cluster

In recent years, the Internet development follow the gold period, the quantity of information commutation on network has an exponential growth. With the performance of network hardware flying to progress, bottleneck effect of network bandwith has been gradually attenuating, and the problem of server performance gradually present out. The capability that the single server system handles the customer request is finite, and making use of server cluster to handle the request of customer that is coming to quickly increase is the hot issue. The server cluster provide flexible scalable network service, and that the load balance of server cluster become an important problem that researcher pay attention to at current, this paper is exactly around this important problem to launch the discussion. First, we discussed the load balancing technique that has been adopted by all kinds of server cluster ,and combining with scientific computing cluster model analyze the related load balance theories. Especially aiming at the DNS load balance strategy, we analyze detailed its excellence and defect and improvement method, and combine on the amount foundation to bring up the a new DNS Dynamic Load Balance (DDLB)technique.The DNS dynamic load balance technique adopted the center dispatch strategy, which has two tiers of load balancer, server pool. The DNS server is load balancer. DNS server and sever pool is in the same super-speed LAN . In that technique, the DNS server can use respectively three kinds of methods to detect surviving of server, according to the surviving of server, dynamic decide whether to resolve the server's domain name or not. At aspects of load scheduling algorithms, on round-robin algorithm's foundation, we add three kinds of load scheduling algorithm, make DNS server can decide the load quantity of each server according to the server's hardware load capability. At the same time, we present a dynamic-feedback load balancing algorithm., Combining the weighted scheduling algorithms, it can adapt the server weights according to dynamic-feedback load information, therefore it can effectively solve the load imbalance problem among the servers.Combining DNS dynamic load balance technique, with the background of DistanceEducation, we design and realize a CSCW load balanced cluster model. This system model include the WEB server, application server and directory server. System provide virtual classroom, and permit client to set up the virtual classroom by himself. We adopt JAVA language to realize virtual classroom, and apply Java applet technique. The load balance adopt two layer construction, one is the client to visit the WEB server, making use of the DNS server to be load dispatcher, the other is client to set up the classroom, making use of the directory server to be load dispatcher, distributing the classroom well balanced to the each application server. At the second load balance layer in the construction, directory server can dynamic acquire the load information of the each application server, and schedule by dynamic-feedback load balancing algorithm. The directory server can still judge the condition of surviving of each application server then to decide whether to distribute load to the server or not.Finally,we make use of the Java language to design and realize the universal telecommunication mechanism .