Split Brain Syndrome – this private network interface or interconnect are redundant and are only used for inter-instance oracle data block transfers. Now talking about split brain concept with respect to oracle RAC systems it occurs when the instance members in a RAC fail to ping/connect to each other via this private interconnect but the servers are all physically up and running and the database instance on each of these servers is also running
Simple Majority Rule according to Oracle “An absolute majority of voting disks configured (more than half) must be available and responsive at all times for Oracle Clusterware to operate” which means to survive from loss of ‘N’ voting disks you must configure at least ‘2N+1′ voting disks. Now we are in a state to understand the use of voting disk in case of heartbeat failure
