Oracle 11G之前的Data Guard恢复模式不能查询,只读模式不能恢复.
在11G之后,增加了Active Data Guard的新特性.它可以兼顾查询和恢复.

实验将一个最大性能模式的物理StandBy转换成最大可用性的Active Data Guard

关于搭建物理StandBy请参考
http://blog.itpub.net/29254281/viewspace-1315088/

1.将备库设置为只读模式(可以简单的重启备库即可)
SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE CANCEL;
Database altered.

SQL> alter database open read only;
Database altered.

如果没有创建StandBy日志文件,则需要创建
alter database add standby logfile group 4 ('/home/oracle/app/oracle/fast_recovery_area/ORCL/onlinelog/standbylog1') size 50m ;
alter database add standby logfile group 5 ('/home/oracle/app/oracle/fast_recovery_area/ORCL/onlinelog/standbylog2') size 50m ;
alter database add standby logfile group 6 ('/home/oracle/app/oracle/fast_recovery_area/ORCL/onlinelog/standbylog3') size 50m ;

2.设置备库在只读模式进行实时恢复
SQL> select open_mode from V$database;
OPEN_MODE
--------------------
READ ONLY

SQL> ALTER DATABASE RECOVER MANAGED STANDBY DATABASE using current logfile disconnect from session;
Database altered.

SQL> select open_mode from V$database;
OPEN_MODE
--------------------
READ ONLY WITH APPLY

3.修改主库的参数,并设置为最高可用性模式
shutdown immediate;
startup mount;
alter system set log_archive_dest_2='service=standby OPTIONAL lgwr sync affirm valid_for=(online_logfiles,primary_roles) db_unique_name=orcl' scope=both;
alter database set standby database to maximize availability;
alter database open;

4.在备库验证.
主库进行增删改查的操作,在备库可以立即看到相关的变更.

参考:
https://blogs.oracle.com/Database4CN/entry/11g_%E6%96%B0%E7%89%B9%E6%80%A7_active_data_guard

ITPub博客

搭建Active Data Guard环境

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