If we are changing spfile in oracle RAC, then we need to use additional SID parameter in the alter system command.

Here SID is the instance_name.

For changing the parameter in both the instances of the RAC.

For changing the parameter in a specific instance.

If we don’t mention the SID parameter, then by default it will be configured for the local instance, from where we are executing the command.

There are 3 options for SCOPE parameter:

1. MEMORY – the change is immediate but will not be available post instance restart
2. SPFILE – the changes will be made to spfile, however it will be applied the database, post instance restart
3. BOTH – Changes will be applied to database immediate, And it dont needs database restart