I go through blogs mentioning what exactly a Split brain syndrome is ( Theoretical Part). All of the business benefits of Oracle RAC. Nodes 1,2 can talk to each other. Providing application-specific failure detection means Oracle Clusterware can fail over not only during the obvious cases such as when the instance is down, but also in the cases when, for example, an application query is not meeting a particular service level. Oracle Security Features prevent unauthorized access and changes. Figure 7-3 shows the Oracle Clusterware configuration after a cold cluster failover has occurred. Split Brain Syndrome in RAC - I am a DBA Applications scale in an Oracle RAC environment to meet increasing data processing demands without changing the application code. The individual nodes are running fine and can accept user connections and work . The recommended high availability and disaster-recovery architectures that use Oracle Data Guard are described in the following sections: Overview of Single Standby Database Architectures, Overview of Multiple Standby Database Architectures. Footnote2Rolling upgrades with Oracle Data Guard incur minimal downtime. A logical copy configured and maintained using Oracle GoldenGate is called a replica, not a logical standby database, because it provides many capabilities that are beyond the scope of the normal definition of a standby database. SELECT statements might be as straightforward as selecting a few . Figure 7-6 Primary and Standby Databases and the Observer During Fast-Start Failover. Clusterware will evaluate cluster resources on implied workload 3. . The clusters that are typical of Oracle RAC environments can provide continuous service for both planned and unplanned outages. In this article I will explore this new feature for one of the possible factors contributing to the node weight, i.e. Then there are two cohorts: {1, 2} and {3}. For example, for a business that has a corporate campus, the extended Oracle RAC configuration could consist of individual Oracle RAC nodes located in separate buildings. The basic function of a cold cluster failover is to monitor a database instance running on a server, and if a failure is detected, to restart the instance on a spare server in the cluster. Oracle Flashback Technology optimizes logical failure repair. To protect against site failures, the MAA recommends that Oracle RAC and Oracle Data Guard reside on separate systems (clusters) and data centers.