逻辑DG之Standby角色转换

Primary:
1.检查当前Primary数据库的初始化参数:
SQL> show parameter fal

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
fal_client                           string      orcl_192.168.1.222
fal_server                           string      orcls_192.168.1.223
SQL> show parameter log_archive_dest

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------

log_archive_dest_1                   string      location=/u01/arch_orcl

log_archive_dest_2                   string      service=orcls_192.168.1.223 lg
                                                 wr async valid_for=(online_log
                                                 files, primary_role) db_unique
                                                 _name=orclldg
2.修改log_archive_dest_1
SQL> alter system set log_archive_dest_1=‘location=/u01/arch_orcl valid_for=(online_logfiles,all_roles) db_unique_name=orclpre‘;

System altered.
Standby:
1.检查当前Standby数据库的初始化参数:
SQL> show parameter log_archive_dest

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest                     string
log_archive_dest_1                   string      location=/u01/arch_ldg valid_f
                                                 or=(online_logfiles,all_roles)
                                                  db_unique_name=orclldg
log_archive_dest_10                  string
log_archive_dest_2                   string      service=orcl_192.168.1.222 arc
                                                 h valid_for=(online_logfiles,
                                                 primary_role) db_unique_name=o
                                                 rclpre
log_archive_dest_3                   string      location=/u01/arch_std valid_f
                                                 or=(standby_logfiles,standby_r
NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
                                                 ole) db_unique_name=orclldg
2.修改log_archive_dest_2为lgwr async
SQL> alter system set log_archive_dest_2=‘service=orcl_192.168.1.222 lgwr async valid_for=(online_logfiles,primary_role) db_unique_name=orclpre‘;

System altered.
3.log_archive_dest_2已经为异步传输
SQL> show parameter archive_dest

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
log_archive_dest                     string
log_archive_dest_1                   string      location=/u01/arch_ldg valid_f
                                                 or=(online_logfiles,all_roles)
                                                  db_unique_name=orclldg
log_archive_dest_10                  string
log_archive_dest_2                   string      service=orcl_192.168.1.222 lgw
                                                 r async valid_for=(online_logf
                                                 iles,primary_role) db_unique_n
                                                 ame=orclpre
log_archive_dest_3                   string      location=/u01/arch_std valid_f
                                                 or=(standby_logfiles,standby_r

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
        ole) db_unique_name=orclldg
4.检查Primary是否配置了Standby Redologs
SQL> select * from v$standby_log;

no rows selected
添加:
SQL> alter database add standby logfile group 4 ‘/u01/app/oracle/oradata/orcl/stdredo01.log‘ SIZE 50m;

Database altered.

SQL> alter database add standby logfile group 5 ‘/u01/app/oracle/oradata/orcl/stdredo02.log‘ SIZE 50m;

Database altered.

SQL> alter database add standby logfile group 6 ‘/u01/app/oracle/oradata/orcl/stdredo03.log‘ SIZE 50m;

Database altered.
5.检查当前Primary数据库状态:
SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
SESSIONS ACTIVE
把Primary置为准备转换状态:
SQL> alter database prepare to switchover to logical standby;

Database altered.

SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
PREPARING SWITCHOVER
再次查看状态变为准备中……,时刻准备着接受来自逻辑Standby数据库(未来新的Primary数据库)发来的REDO数据。
6.把当前的逻辑Standby转换为Primary
SQL> alter database prepare to switchover to primary;

Database altered.

SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
PREPARING SWITCHOVER
再次查看状态变为准备中……
7.查看Primary数据库
SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
TO LOGICAL STANDBY
此次检查结果关系到switchover转换是否能够成功。
8.把当前的Primary转换成逻辑Standby
SQL> alter database commit to switchover to logical standby;

Database altered.
9.逻辑Standby在接收到前Primary的转换消息,并完成相关的REDO数据之后,会自动暂停SQL应用。如果之前没有启动REDO应用,现在启动还不晚。
SQL> alter database start logical standby apply;

Database altered.

SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
PREPARING SWITCHOVER  等会……

SQL> select switchover_status from v$database;

SWITCHOVER_STATUS
--------------------
TO PRIMARY
10.转换逻辑Standby为新的Primary数据库
SQL> alter database commit to switchover to primary;

Database altered.
启动新的逻辑Standby(之前的Primary)SQL应用
SQL> alter database start logical standby apply immediate;

Database altered.
测试:
在新的Primary里面插入测试数据:
SQL>  select * from scott.test;

        ID
----------
         1
         2
         3

SQL> insert into scott.test values(4);      

1 row created.

SQL> commit;

Commit complete.

检查新的standby:
SQL> select * from scott.test;

        ID
----------
         1
         2
         3

SQL> select * from scott.test;

        ID
----------
         1
         2
         3

SQL> select * from scott.test;

        ID
----------
         1
         2
         3
可能会延迟……
SQL> select * from scott.test;

        ID
----------
         1
         2
         3
         4
逻辑Standby角色转换成功……

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逻辑DG之Standby角色转换

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