10g_dataguard_failover
大体步骤：
1、启动failover
SQL> alter database recover managed standby database finish force;
FORCE 关键字将会停止当前活动的RFS 进程，以便立刻执行failover。
剩下的步骤就与前面switchover 很相似了
2、切换物理standby 角色为primary
SQL> alter database commit to switchover to primary;
3、启动新的primary 数据库。
SQL> alter database open;
这样就可以了，不需要在主库上做啥操作。
如果想再将已经切换的系统变回原形，那就需要重新配置dg，因为在failover之后，原来的主库就不是dg的一部分了。如果重新配置dg，那就要以原来的备库（现在的主库）作为主库了，因为他在后续有很多操作了已经（无论是测试还是真正的火灾他必定是已经当了很久的主库了），待重新配置完dg之后，再做一次switchover切换，就可以将dg完完全全的恢复到我们所有测试之前的角色模式了。
实验：
环境：
主库：150-----因为是failover，所以在切换角色时150不需要做任何操作
备库：200
1、200上：
SQL> alter database recover managed standby database finish force;
SQL> alter database commit to switchover to primary;
SQL> alter database open;
SQL> select switchover_status from v$database;
2、此时查看原来的主库150的状态
解析：如果想再将已经切换的系统变回原形，那就需要重新配置dg，因为在failover之后，原来的主库就不是dg的一部分了。如果重新配置dg，那就要以原来的备库（现在的主库）作为主库了，因为他在后续有很多操作了已经（无论是测试还是真正的火灾他必定是已经当了很久的主库了），待重新配置完dg之后，再做一次switchover切换，就可以将dg完完全全的恢复到我们所有测试之前的角色模式了
3、重新配置DG以便将所有角色切换到最开始的状态（150主库，200备库）
3.1 参数文件不需要改变
3.2 在200（此时主库）创建备库控制文件并scp到150
[oracle@stream dbs]$ sqlplus / as sysdba
SQL> create spfile from pfile;
SQL> startup mount
SQL> alter database create standby controlfile as '/u01/control01.dbf';
SQL> exit
[oracle@stream dbs]$ cd /u01
[oracle@stream u01]$ scp control01.dbf 192.168.249.150:/u01/app/oracle/oradata/ora10g/
3.3 将200（此时主库）的数据文件和日志文件传到150上
[oracle@stream u01]$ cd app/oracle/oradata/ora10g/
[oracle@stream ora10g]$ scp *.dbf *.log 192.168.249.150:/u01/app/oracle/oradata/ora10g/
3.4 在200上将主库启动到open状态
[oracle@stream ora10g]$ sqlplus / as sysdba
SQL> alter database open;
SQL> select name,database_role,open_mode,protection_mode from v$database;
NAME DATABASE_ROLE OPEN_MODE PROTECTION_MODE
--------- ---------------- ---------- --------------------
ORA10G PRIMARY READ WRITE MAXIMUM PERFORMANCE
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS---状态不正常应该是因为150（备库）还没有mount，也没应用redo
--------------------
NOT ALLOWED
3.5 启动此时的备库150到mount
SQL> startup mount
ORACLE instance started.
Total System Global Area 373293056 bytes
Fixed Size 1273780 bytes
Variable Size 113246284 bytes
Database Buffers 255852544 bytes
Redo Buffers 2920448 bytes
Database mounted.
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
--------------------
TO PRIMARY
SQL> archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /arch/log
Oldest online log sequence 1
Next log sequence to archive 2
Current log sequence 2
SQL> archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /arch/log
Oldest online log sequence 1
Next log sequence to archive 2
Current log sequence 2
3.6 备库应用redo
SQL> alter database recover managed standby database disconnect from session;
Database altered.
3.7 在200上切换日志
SQL> archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /arch/log
Oldest online log sequence 3
Next log sequence to archive 5
Current log sequence 5
SQL> alter system switch logfile;
System altered.
SQL> /
System altered.
SQL> /
System altered.
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS---
--------------------
TO STANDBY
SQL> !date
Fri May 11 00:41:35 CST 2012
3.8 备库查看归档是否已经传递过来
SQL> archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /arch/log
Oldest online log sequence 1
Next log sequence to archive 2
Current log sequence 2
SQL> archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /arch/log
Oldest online log sequence 1
Next log sequence to archive 2
Current log sequence 2
SQL> archive log list
Database log mode Archive Mode
Automatic archival Enabled
Archive destination /arch/log
Oldest online log sequence 1
Next log sequence to archive 0
Current log sequence 8
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
--------------------
SESSIONS ACTIVE
待DG重新搭建好以后（200为主库，150为备库），现在再将150变为主库，200变为备库
4、 切换
4.1 200上
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
--------------------
TO STANDBY
SQL> !date
Fri May 11 00:41:35 CST 2012
SQL> alter database commit to switchover to physical standby;
Database altered.
SQL> shutdown immediate
ORA-01507: database not mounted
ORACLE instance shut down.
SQL> startup mount
ORACLE instance started.
Total System Global Area 373293056 bytes
Fixed Size 1273780 bytes
Variable Size 113246284 bytes
Database Buffers 255852544 bytes
Redo Buffers 2920448 bytes
Database mounted.
SQL> alter database recover managed standby database disconnect from session;
Database altered.
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
--------------------
SESSIONS ACTIVE
SQL> select name,database_role,open_mode,protection_mode from v$database;
NAME DATABASE_ROLE OPEN_MODE PROTECTION_MODE
--------- ---------------- ---------- --------------------
ORA10G PHYSICAL STANDBY MOUNTED MAXIMUM PERFORMANCE
4.2 150上：
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
--------------------
SESSIONS ACTIVE
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
--------------------
TO PRIMARY
SQL> alter database commit to switchover to primary;
Database altered.
SQL> alter database open;
Database altered.
SQL> select name,database_role,open_mode,protection_mode from v$database;
NAME DATABASE_ROLE OPEN_MODE PROTECTION_MODE
--------- ---------------- ---------- --------------------
ORA10G PRIMARY READ WRITE MAXIMUM PERFORMANCE
SQL> select switchover_status from v$database;
SWITCHOVER_STATUS
--------------------
TO STANDBY
5、此时已经完全恢复到我们所做测试前的状态
测试完毕！！
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