查看备库：
SQL> SELECT SWITCHOVER_STATUS FROM V$DATABASE;
SWITCHOVER_STATUS
--------------------
TO PRIMARY
查看主库：
SQL> SELECT SWITCHOVER_STATUS FROM V$DATABASE;
SWITCHOVER_STATUS
--------------------
NOT ALLOWED
再次查看主库的参数：
SQL> show parameter LOG_ARCHIVE_DEST_2
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_2 string service=standby lgwr async noa
ffirm
原来这里设置错误：
SQL> alter system set log_archive_dest_2='service=bhoms02 async valid_for=(online_logfiles,primary_role) db_unique_name=bhoms02';
再查主库：
SQL> SELECT SWITCHOVER_STATUS FROM V$DATABASE;
SWITCHOVER_STATUS
--------------------
TO STANDBY
查看备库：
SQL> show parameter LOG_ARCHIVE_DEST_2
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest_2 string service=standby lgwr async noa
ffirm
原来这里设置错误：
SQL> alter system set log_archive_dest_2='service=bhoms01 async valid_for=(online_logfiles,primary_role) db_unique_name=bhoms01';
重启备库，解决问题：
SQL> shutdown immediate;
ORA-01109: database not open
Database dismounted.
ORACLE instance shut down.
SQL> startup nomount
ORACLE instance started.
Total System Global Area 6747725824 bytes
Fixed Size 2213976 bytes
Variable Size 5100275624 bytes
Database Buffers 1610612736 bytes
Redo Buffers 34623488 bytes
SQL> alter database mount standby database;
Database altered.
SQL> alter database open read only;
Database altered.
SQL> alter database recover managed standby database disconnect from session;
Database altered.