【DG】主备切换
一：DG之主备切换（主切备、备切主）
1）主切备：
SYS@ORA11GR2>select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PRIMARY SESSIONS ACTIVE
SYS@ORA11GR2>alter database commit to switchover to physical standby with session shutdown; （主切备，后台进程关掉了数据库）
ERROR:
ORA-01034: ORACLE not available
Process ID: 17761
Session ID: 106 Serial number: 1421
Database altered.
SYS@ORA11GR2>conn / as sysdba
Connected to an idle instance.
SYS@ORA11GR2>startup mount;
ORACLE instance started.
Total System Global Area 830930944 bytes
Fixed Size 2257800 bytes
Variable Size 503319672 bytes
Database Buffers 322961408 bytes
Redo Buffers 2392064 bytes
Database mounted.
SYS@ORA11GR2>select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PHYSICAL STANDBY RECOVERY NEEDED
——需应用日志：
SYS@ORA11GR2>recover managed standby database using current logfile disconnect from session;
Media recovery complete.
此时转换后的备库一直在应用日志，如果需要再次转换为主库需结束应用日志：
SYS@ORA11GR2>select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PHYSICAL STANDBY TO PRIMARY
2）备切主：
[oracle@bing ~]$ export ORACLE_SID=OCMU
[oracle@bing ~]$ echo $ORACLE_SID
OCMU
[oracle@bing ~]$ sqlplus / as sysdba
SQL*Plus: Release 11.2.0.4.0 Production on Thu Oct 20 13:25:13 2016
Copyright (c) 1982, 2013, Oracle. All rights reserved.
Connected to:
Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
SQL> select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PHYSICAL STANDBY NOT ALLOWED (没有主库，状态显示不正常，正常应为to primary)
——切换一下
SQL> alter database commit to switchover to primary with session shutdown;
alter database commit to switchover to primary with session shutdown
*
ERROR at line 1:
ORA-16139: media recovery required
——根据提示，应用日志：
SQL> recover managed standby database using current logfile disconnect from session;
Media recovery complete.
再次查看状态：
SQL> select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PHYSICAL STANDBY TO PRIMARY（正常了）
（因为有主库，则状态为not allowed；如果没有主库，则状态都为to primary）
——备切主操作：
SQL> alter database commit to switchover to primary with session shutdown;
（备切主后，后台进程直接关库，再将库启动到mount下）
Database altered.
SQL> select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PRIMARY NOT ALLOWED （备切主后数据库状态为mount）
——启库：
SQL> alter database open;
Database altered.
SQL> select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PRIMARY RESOLVABLE GAP
——转换后的备库正在应用日志，过会再看一下转换后的主库状态：
SQL> select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PRIMARY TO STANDBY（正常）
——过会再看一下转换后的主库状态：
SQL> select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PRIMARY SESSIONS ACTIVE（正常）
二：反切（即将切换后的备库切换回主库，切换后的主库切换回备库）
1）.主切备操作：
SQL> select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PRIMARY SESSIONS ACTIVE
SQL> alter database commit to switchover to physical standby with session shutdown;
Database altered. （主切备，后台进程关掉了数据库）
SQL> select open_mode from v$database;
select open_mode from v$database
*
ERROR at line 1:
ORA-01034: ORACLE not available
Process ID: 8010
Session ID: 1 Serial number: 7
SQL> conn / as sysdba
Connected to an idle instance.
SQL> startup mount;
ORACLE instance started.
Total System Global Area 830930944 bytes
Fixed Size 2257800 bytes
Variable Size 675286136 bytes
Database Buffers 150994944 bytes
Redo Buffers 2392064 bytes
Database mounted.
SQL>
SQL> select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PHYSICAL STANDBY RECOVERY NEEDED
SQL> recover managed standby database using current logfile disconnect from session;
Media recovery complete.
SQL> select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PHYSICAL STANDBY TO PRIMARY
SQL> recover managed standby database cancel;
Media recovery complete.
SQL>
2）.备切主操作：
SYS@ORA11GR2>select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PHYSICAL STANDBY TO PRIMARY
SYS@ORA11GR2>alter database commit to switchover to primary with session shutdown;
Database altered. （备切主后，后台进程直接关库，再将库启动到mount下）
SYS@ORA11GR2>alter database open;
Database altered.
SYS@ORA11GR2>select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PRIMARY SESSIONS ACTIVE
3）.再次查看下切换后的备库状态：
SQL> select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PHYSICAL STANDBY RECOVERY NEEDED
SQL> recover managed standby database using current logfile disconnect from session;
Media recovery complete.
SQL>
SQL> select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PHYSICAL STANDBY NOT ALLOWED
SQL> recover managed standby database cancel;
Media recovery complete.
SQL> select database_role,switchover_status from v$database;
DATABASE_ROLE SWITCHOVER_STATUS
---------------- --------------------
PHYSICAL STANDBY NOT ALLOWED
完成！！！！！！！！！！！！！！！！！！
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转载于:http://blog.itpub.net/31397003/viewspace-2126910/