New requests are accepted after the Split-Brain event and then performed on potentially corrupted system state (thus potentially corrupting system state even further). To simulate loss of connectivity between two nodes, stop the private network service on one of the nodes: Verify that host01 is retained as it has a lower node number and host02 is evicted: To simulate loss of connectivity between two nodes, stop private network service on one of the nodes: Verify that host02 is retained as it has higher number of database services executing and host01 is evicted although it has a lower node number: If the sub-clusters are of the different sizes, the functionality is same as earlier, i.e. Prior to Oracle Database 12.1.0.2c, the algorithm to determine the node(s) to be retained / evicted is as follows: However, starting from 12.1.0.2c, in case of split brain, some improvement has been made to node eviction algorithm. The production database transmits redo data (either synchronously or asynchronously) to redo log files at the physical standby database. What is Voting Disk & Split Brain Syndrome in RAC Rolling upgrade and patch capabilities for Oracle Clusterware with zero database downtime. End-users connect to clusters through a public network. (See Section 7.1.5 for a complete description.). Oracle Application Server instances can be installed in either site as long as they do not interfere with the instances in the disaster recovery setup. In addition, allowing maintenance operations to occur on a subset of components in the cluster while the application continues to run on the rest of the cluster can reduce planned downtime. Name of the cluster: Cluster01.example.com, Number of nodes: 3 (host01, host02, host03), Instances of RAC database: admindb1 on host01. Ina cluster, a private interconnect is used by cluster nodes to monitor each nodes status and communicate with each other. If you configure a single voting disk, then you should use external mirroring to provide redundancy. It is possible, under certain circumstances, to build and deploy an Oracle RAC system where the nodes in the cluster are separated by greater distances. Following the execution of a SELECT statement, a tabular result is held in a result table (called a result set). If your business does not require the scalability and additional high availability benefits provided by Oracle RAC, but you still need all the benefits of Oracle Data Guard and cold cluster failover, then Oracle Database with Oracle Clusterware and Oracle Data Guard is a good compromise architecture.