1、单节点启动时，是可以操作的
[oracle@rac1 ~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.3.0 Production on Thu Jul 11 11:54:29 2019

Copyright (c) 1982, 2011, Oracle.  All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Data Mining and Real Application Testing options

SQL> SELECT inst_name FROM v$active_instances;

INST_NAME
--------------------------------------------------------------------------------
rac1:RAC1

SQL> exit
Disconnected from Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Data Mining and Real Application Testing options
[oracle@rac1 ~]$ 

2、新节点加入问题，正常运行后是否自动加入（是）
[oracle@rac1 ~]$ sqlplus / as sysdba

SQL*Plus: Release 11.2.0.3.0 Production on Thu Jul 11 12:01:42 2019

Copyright (c) 1982, 2011, Oracle.  All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Data Mining and Real Application Testing options

SQL> SELECT inst_name FROM v$active_instances;

INST_NAME
--------------------------------------------------------------------------------
rac1:RAC1
rac2:RAC2

SQL> 

3、默认rac是自动启动相关服务的
4、非图形化并没有节省多少资源