dataguard的搭建就完成了，可以在主库切换日志查看是否在备库数据库日志中会应用日志
Media Recovery Waiting for thread 1 sequence 12 (in transit)
Recovery of Online Redo Log: Thread 1 Group 4 Seq 12 Reading mem 0
Mem# 0: /DATA/app/oracle/oradata/test11g/redo04.log
11g备库使用active dataguard特性。
SQL> alter database open;
Database altered.
SQL> recover managed standby database using current logfile disconnect from session;
Media recovery complete.
switchover的问题答疑
如果出现下面的错误，很可能当前操作系统用户下安装了多个数据库实例，取消默认的ORACLE_SID即可。
或者直接使用dgmgrl sys/oracle@test11g 这种方式连接
DGMGRL> switchover to 'stest11g';
Performing switchover NOW, please wait...
Operation requires a connection to instance "test11g" on database "stest11g"
Connecting to instance "test11g"...
ORA-01017: invalid username/password; logon denied
Warning: You are no longer connected to ORACLE.
connect to instance "test11g" of database "stest11g"
切换正常，但是需要手工启动备库，切换其实是正常的，需要手工启动一下主库
主要原因就是在listener.ora中需要配置一个xxxx_DGMGRL的global_name
DGMGRL> switchover to stest11g
Performing switchover NOW, please wait...
Operation requires a connection to instance "test11g" on database "stest11g"
Connecting to instance "test11g"...
Connected.
New primary database "stest11g" is opening...
Operation requires startup of instance "test11g" on database "test11g"
Starting instance "test11g"...
Unable to connect to database
ORA-12514: TNS:listener does not currently know of service requested in connect descriptor
Failed.
Warning: You are no longer connected to ORACLE.
Please complete the following steps to finish switchover:
start up instance "test11g" of database "test11g"
如果配置完全正确，正常切换的日志就会如下：
DGMGRL> switchover to stest11g;
Performing switchover NOW, please wait...
Operation requires a connection to instance "test11g" on database "stest11g"
Connecting to instance "test11g"...
Connected.
New primary database "stest11g" is opening...
Operation requires startup of instance "test11g" on database "test11g"
Starting instance "test11g"...
ORACLE instance started.
Database mounted.
Database opened.
Switchover succeeded, new primary is "stest11g"
DGMGRL>
最后还是希望大家能够合理使用dataguard,一切顺利。
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