How to change SGA in Oracle RAC

Node One :   RACATTACK56U
Node Two :   RACATTACK57U
Node Three : RACATTACK58U

Verify Current Memory Parameters before the change:

Connect To RACATTACK56U:

export ORACLE_SID=RAC1
. oraenv
sqlplus as / sysdba

SQL> show parameter sga_max_size
NAME           TYPE        VALUE
-------------- ----------- ------
sga_max_size   big integer 4G

SQL> show sga
Total System Global Area    9620525056 bytes
Fixed Size                     2229624 bytes
Variable Size               4630514312 bytes
Database Buffers            4966055936 bytes
Redo Buffers                  21725184 bytes

SQL> alter system set sga_max_size=9g sid='*' scope=spfile;
SQL> exit;

shutdown database PROD (three instances should be shut down)
$ srvctl stop database -d RAC
$ srvctl START database -d RAC

Verify Current Memory Parameters after the change:

export ORACLE_SID=RAC1
. oraenv
sqlplus as / sysdba

SQL> show parameter sga_max_size
NAME           TYPE        VALUE
-------------- ----------- ------
sga_max_size   big integer 9G