Modify Parameter in RAC Environment

You can modify the value of your initialization parameters by using the ALTER SYSTEM SET command. This is the same as with a single-instance database except that you have the possibility to specify the SID clause in addition to SCOPE clause.

SQL>alter system set <dpname> scope=<svalue> sid='<sid|*>';

The default value for the sid clause is sid='*'.
Specify sid='*' or use default value, if you want to change the value of the parameter for all instances.
Specify sid='sid' if you want to change the value of the parameter only for the instance sid.

The <sid>.<pname> will override the value of <sid>.<pname>.

The sid='sid' of the ALTER SYSTEM RESET command allows you to override the precedence of a currently used <sid>.<pname> entry. The <sid>.<pname> entry will be deleted. Oracle use the value of *.<pname> for instance 'sid'.

SQL>alter system reset <dpname> sid='<sid>';

The following command will reset the value for instance * from instance sid.

SQL>alter system reset <dpname> scope='spfile' sid='*';

You must specify scope as 'spfile', because you can reset memory value for instance * from instance sid.