1. Master can be found by searching ORACLE_HOME/log/nodename/cssd/ocssd.log.
2. For master of a enqueue resource with Oracle RAC, you can select from v$ges_resource view. Check for the "master_node" column.
Hope it helps...
There is no such thing as "master node" in RAC configurations. All nodes are equal.
Sebastian wrote: 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.