如何判断oracle是否rac模式，即是否是集群

采样rac集群

[oracle@shdb02 ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Wed Mar 16 11:56:36 2022
Copyright (c) 1982, 2013, Oracle.  All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, Real Application Clusters, Automatic Storage Management, OLAP,
Data Mining and Real Application Testing options

SQL> SELECT value FROM v$parameter where name = 'cluster_database';

VALUE
--------------------------------------------------------------------------------
TRUE

 SQL> select inst_id,instance_number,instance_name,host_name,status from gv$instance;

INST_ID INSTANCE_NUMBER INSTANCE_NAME   HOST_NAME STATUS

   2      2                hts2           shdb02    OPEN

   1      1                hts1           shdb01    OPEN 

 SQL> show parameter cluster_database;

 NAME TYPE VALUE
 ------------------------------------ ----------- -------- 
 cluster_database boolean    TRUE
 cluster_database_instances integer 2

  

 SQL> select * from v$option a where a.PARAMETER='Real Application Clusters';

  PARAMETER                        VALUE
  ----------------------------------------------------------------
  Real Application Clusters        TRUE

采样单数据库架构

[root@oraclemachine ~]# su - oracle
Last login: Tue Mar 15 23:37:30 CST 2022 on pts/0
oracle@prd:/home/oracle$echo $ORACLE_SID
prod
oracle@prod:/home/oracle$sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Wed Mar 16 11:21:55 2022
Copyright (c) 1982, 2013, Oracle.  All rights reserved.

Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

SQL> SELECT value FROM v$parameter where name = 'cluster_database';

VALUE
--------------------------------------------------------------------------------
FALSE

 SQL> select inst_id,instance_number,instance_name,host_name,status from gv$instance;

INST_ID INSTANCE_NUMBER INSTANCE_NAME  HOST_NAME  STATUS

  1      1                prod          rac-12c-2   OPEN 

 SQL> show parameter cluster_database;

 NAME            TYPE             VALUE
 ------------------------------
 cluster_database boolean          FALSE
 cluster_database_instances integer 1
 

 SQL> select * from v$option a where a.PARAMETER='Real Application Clusters';

  PARAMETER                 VALUE
  ------------------------------------------------------------------ 
  Real Application Clusters FALSE