[Oracle] RAC-Server Load balancer

[Oracle] RAC-Server Load balancer distributes loads evenly to each node in the cluster to improve overall performance. Oracle RAC provides two methods to achieve load balancing. The first is pure technical means, that is, when a user connects, the node that determines based on the current load of the system to process user requests; the second type is business-oriented. Applications are divided into many services manually, and connection requests from a service are processed by a node. Let's take a look at these two methods: pure technical means (connection-oriented load balancing) 1. the Client Server Load balancer configuration method is in the client tnsnames. set LOAD_BALANCE = YES in the ora file. When the client initiates a connection, it randomly selects one from the address list to randomly distribute the connection requests to each instance. The biggest disadvantage of this technology is that it is too rough to distribute requests based on the actual load of each instance, so it is rarely used. 2. Server Load balancer the Server Load balancer depends on the load information collected by Listener. During database operation, the pmon Process collects system load information and regularly updates it to Listener. If you have configured the Remote_listener parameter, the pmon process not only registers the load information to the local Listener, but also registers the Listener of other instances. With the pmon automatic registration mechanism, the Listener of each node in the cluster can master the load information of all nodes. When a client request is received, the connection is allocated to the instance with the smallest load. Service-oriented means (using Service load balancing) the Server Load balancer conducted by pure technical means seems beautiful, but in actual use, it may bring about very large performance problems. As we all know, due to its share-disk architecture, RAC's performance depends largely on the memory Fusion (Cache Fusion). It cannot know the specific business conditions by pure technical means, therefore, it may distribute the connection of the same service to various instances, resulting in a large amount of memory convergence and a sharp reduction in performance. If we use another method to allocate the connection of the same application to the same instance, for example, the connection of application A is connected to instance, B applications are connected to B instances, which can effectively reduce memory convergence. Application division can be achieved through service, which requires DBA and open personnel to work together to configure service