如何查看oracle RAC是否启用

查看oracle RAC是否启用：
标准连接：
[oracle@yans1 ~]$ sqlplus "/ as sysdba"

SQL*Plus: Release 10.2.0.3.0 - Production on 星期五 11月 13 13:12:54 2009

Copyright (c) 1982, 2006, Oracle.  All Rights Reserved.


Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production
With the Partitioning, OLAP and Data Mining options

RAC数据库：
bash-3.00$ sqlplus "/ as sysdba"

SQL*Plus: Release 10.2.0.3.0 - Production on 星期五 11月 13 13:40:28 2009

Copyright (c) 1982, 2006, Oracle.  All Rights Reserved.


connect to: 
Oracle Database 10g Enterprise Edition Release 10.2.0.3.0 - 64bit Production
With the Partitioning, Real Application Clusters, OLAP and Data Mining options

据此可以判断出oracle是否使用了RAC。