启动 Oracle 11g RAC数据库时出现以下错误。只能启动其中一个节点（rac01）,另一个节点启动不了（rac02）。可能是以前修改cluster_database这个参数引起的。在Oracle RAC架构这个参数必须设置为TRUE。
执行startup时候，错误信息: ORA-01102: cannot mount database in EXCLUSIVE mode
解决方法:
rac01节点:
SQL> show parameter cluster_database;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
cluster_database boolean FALSE
cluster_database_instances integer 1
SQL> alter system set cluster_database=true scope=spfile;
System altered.
SQL> shutdown immediate
Database closed.
Database dismounted.
ORACLE instance shut down.
SQL> startup
ORACLE instance started.
Total System Global Area 1068937216 bytes
Fixed Size 2260088 bytes
Variable Size 734004104 bytes
Database Buffers 327155712 bytes
Redo Buffers 5517312 bytes
Database mounted.
Database opened.
SQL> select open_mode from v$database;
OPEN_MODE
--------------------
READ WRITE
SQL> show parameter cluster_database;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
cluster_database boolean TRUE
cluster_database_instances integer 2
SQL>
rac02节点:
[oracle@fanxin02 ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Tue May 21 23:08:16 2019
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to an idle instance.
SQL> startup ORACLE instance started.
Total System Global Area 1068937216 bytes
Fixed Size 2260088 bytes
Variable Size 734004104 bytes
Database Buffers 327155712 bytes
Redo Buffers 5517312 bytes
Database mounted.
Database opened.
SQL> show parameter cluster_database;
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
cluster_database boolean TRUE
cluster_database_instances integer 2
SQL>
SQL> archive log list;
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /u01/app/oracle/product/11.2.0.4/db_1/dbs/arch
Oldest online log sequence 12
Next log sequence to archive 13
Current log sequence 13
SQL>
出自：http://blog.itpub.net/31562900/viewspace-2564139