oracle adg切换

作者：广大

1 主库转备库

注意：原则上至多只能有一个主库，但是备库可以多个，所以需要先进行主库转备库操作。

1.1 查看主库角色切换状态

SYS@proe>select name,database_role,switchover_status from v$database;

NAME                      DATABASE_ROLE    SWITCHOVER_STATUS
------------------------- ---------------- --------------------
PROE                      PRIMARY          TO STANDBY

1.2 正常主库切换备库命令

SYS@proe>alter database commit to switchover to physical standby;

Database altered.

1.3 执行切换后的操作

SYS@proe>shutdown abort
ORACLE instance shut down.
SYS@proe>startup mount;
ORACLE instance started.
# 查看此时角色切换状态
SYS@proe>select name,database_role,switchover_status from v$database;

NAME                      DATABASE_ROLE    SWITCHOVER_STATUS
------------------------- ---------------- --------------------
PROE                      PHYSICAL STANDBY RECOVERY NEEDED
# 查看角色保护模式和级别
SYS@proe> select name,database_role,protection_mode,protection_level from v$database;

NAME                      DATABASE_ROLE    PROTECTION_MODE      PROTECTION_LEVEL
------------------------- ---------------- -------------------- --------------------
PROE                      PHYSICAL STANDBY MAXIMUM AVAILABILITY MAXIMUM AVAILABILITY

1.4 异常切换命令

"TO STANDBY"意味着主库此时可以切换为备库，如果状态为SESSION ACTIVE可以使用以下命令切换。然后执行上述切换后的操作。

SYS@proe>alter database commit to switchover to physical standby with session shutdown;

2 备库转主库

2.1 查看备库角色切换状态

SYS@stddb>select name,database_role,switchover_status from v$database;

NAME      DATABASE_ROLE    SWITCHOVER_STATUS
--------- ---------------- --------------------
PROE      PHYSICAL STANDBY TO PRIMARY

2.2 备库切换主库命令

SYS@stddb>alter database commit to switchover to primary;

Database altered.

2.3 执行切换后的操作

# 查看此时角色切换状态
SYS@stddb>select name,database_role,switchover_status from v$database;

NAME      DATABASE_ROLE    SWITCHOVER_STATUS
--------- ---------------- --------------------
PROE      PRIMARY          NOT ALLOWED
# 查看角色保护模式和级别
SYS@stddb>select name,database_role,protection_mode,protection_level from v$database;

NAME      DATABASE_ROLE    PROTECTION_MODE      PROTECTION_LEVEL
--------- ---------------- -------------------- --------------------
PROE      PRIMARY          MAXIMUM PERFORMANCE  UNPROTECTED
# 备库切换为主库后实例状态
SYS@stddb>select instance_name,status from v$instance;

INSTANCE_NAME    STATUS
---------------- ------------
stddb            MOUNTED
# 将数据库启动到open
SYS@stddb>alter database open;

Database altered.
# 再次查看转换后的角色保护模式及级别，可以看到和原来的主库一致。
SYS@stddb>select database_role,protection_mode,protection_level from v$database;

DATABASE_ROLE    PROTECTION_MODE      PROTECTION_LEVEL
---------------- -------------------- --------------------
PRIMARY          MAXIMUM PERFORMANCE  MAXIMUM PERFORMANCE

3 启动现在备库日志应用服务

原来的主库已经切换为备库，查看此时数据库打开模式

SYS@proe>select name,open_mode from v$database;

NAME                      OPEN_MODE
------------------------- --------------------
PROE                      MOUNTED

数据库启动到open

SYS@proe>alter database open;

Database altered.

启动数据库的日志应用服务

SYS@proe>alter database recover managed standby database using current logfile disconnect;
Database altered.
# 查看数据库打开模式
SYS@proe>select name,open_mode from v$database;

NAME                      OPEN_MODE
------------------------- --------------------
PROE                      READ ONLY WITH APPLY

一次完整的主备切换完成

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