No, a change to DB_FILES requires a complete outage.

Certain INIT parameters must have the same value across all active instances.

For example, these include but are not restricted to, the following parameters:

  ACTIVE_INSTANCE_COUNT, CLUSTER_DATABASE_INSTANCES, COMPATIBLE, CONTROL_FILES, DB_FILES, DB_NAME, DB_UNIQUE_NAME, UNDO_MANAGEMENT

None of these parameters can be changed in a RAC rolling fashion.

Any attempt to do so will result in errors.

For example, an attempt to change DB_FILES while other instances are active will result in the following:

SQL> alter system set db_files=201 sid='*' scope=spfile;

System altered.

SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.

Total System Global Area  392495104 bytes
Fixed Size            2228704 bytes
Variable Size          230690336 bytes
Database Buffers      155189248 bytes
Redo Buffers            4386816 bytes
ORA-01105: mount is incompatible with mounts by other instances
ORA-01174: DB_FILES is 201 buts needs to be 200 to be compatible

Solution:
--------

1. Set the parameter in spfile.

      SQL> alter system set db_files=<new_value> sid='*' scope=spfile;

e.g.

      SQL> alter system set db_files=201 sid='*' scope=spfile;

2. Bounce the complete database

      $ srvctl stop database -d <db_name>

      $ srvctl start database -d <db_name>