If you see Fatal NI connect error 12547 error in alert log file of a Database in the middle of startup, and the database process couldn’t find DB PARAMETER FILE and CONTROL FILE, you have to check permissions,owner and group of these files:
ls -l $GRID_HOME/bin/oracle ls -l $ORACLE_HOME/bin/oracle
The permission of these files have to be 6751.
The group of these files have to be oinstall
The owner of first file have to be grid and the owner of second one have to be oracle
chown grid:oinstall $GRID_HOME/bin/oracle chmod 6751 $GRID_HOME/bin/oracle chown oracle:oinstall $ORACLE_HOME/bin/oracle chmod 6751 $ORACLE_HOME/bin/oracle