I have learned somewhere the node with the least node number will become master node.The information which you want is not documented (far as I know). What is difficult to accurately tell you the truth.
How oracle decides which node will have highest node and which will have lowest node number?
ssolbach wrote:From here is not documented. So we can not answer.
The only thing closest to something like a "Master" is that only one node has the role to update the Oracle Cluster Registry (OCR), all other nodes only read the OCR.
However this is just a role, which can easily switch between the nodes (but is normally fix as long as the responsible nodes lives).
This node hover is then called OCR master.
Since you already need someone writing the OCR when you start the cluster it is naturally, that the first node started gets this role.
If this node hover dies, the next node started after that one will get the role. If this one dies then, it will go to the next node and so forth.
But since this is just a role, which will fall to any node available, someone really has not to care about it.