Oracle DG Broker 进行 SwitchOver & Failover，Failover后恢复主从同步
前一篇 Oracle DG 手动 SwitchOver & Failover，Failover后利用闪回恢复同步_Hehuyi_In的博客-CSDN博客介绍了SwitchOver & Failover的概念、区别及利用sql操作的方法。可以看到利用sql来执行需要在主从库均进行操作，命令也多，较为复杂，本篇来看如何利用DG Broker来简化这些操作。
注意：配置期间已有主从同步会中断，若当前从库已在使用，需要告知业务方，申请操作窗口
一、 DG Broker安装与配置
| 现有架构：以一主两备为例 | ||||
|---|---|---|---|---|
| 数据库 IP | db_unique_name | 配置DG Broker时角色 | switchover后角色 | failover后角色 |
| 192.168.3.224 | prodcdb | 从库 | 主库 | 从库 |
| 192.168.3.225 | prodcdb_dg | 主库 | 从库 | 主库 |
| 192.168.3.226 | prodcdb_dg02 | 从库 | 从库 | 从库 |
1. DG Broker安装
DG Broker其实就是dgmgrl工具，安装Oracle数据库软件或完整的客户端都包含该工具，本文略。
2. 监听修改
按下面修改监听配置，如果不修改利用原有的监听也可以，后面会介绍这种方法
prodcdb_dg（主库）
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(GLOBAL_DBNAME = pdb_fsfo)
(SID_NAME = prodcdb)
)
(SID_DESC =
(GLOBAL_DBNAME = prodcdb)
(ORACLE_HOME = /data/prd/oracle/database/19.3.0.0/prod_cdb)
(SID_NAME = prodcdb)
)
(SID_DESC =
(GLOBAL_DBNAME = prodcdb_dg_DGMGRL) # 新增部分，名称为db_unique_name_DGMGRL
(ORACLE_HOME = /data/prd/oracle/database/19.3.0.0/prod_cdb)
(SID_NAME = prodcdb)
)
)
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.3.225)(PORT = 1521))
)
)
)prodcdb（备库1）
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(GLOBAL_DBNAME = pdb_fsfo)
(SID_NAME = prodcdb)
)
(SID_DESC =
(GLOBAL_DBNAME = prodcdb)
(ORACLE_HOME = /data/prd/oracle/database/19.3.0.0/prod_cdb)
(SID_NAME = prodcdb)
)
(SID_DESC =
(GLOBAL_DBNAME = prodcdb_DGMGRL) # 新增部分，名称为db_unique_name_DGMGRL
(ORACLE_HOME = /data/prd/oracle/database/19.3.0.0/prod_cdb)
(SID_NAME = prodcdb)
)
)
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.3.224)(PORT = 1521))
)
)
)prodcdb_dg02（备库2）
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(GLOBAL_DBNAME = pdb_fsfo)
(SID_NAME = prodcdb)
)
(SID_DESC =
(GLOBAL_DBNAME = prodcdb)
(ORACLE_HOME = /data/prd/oracle/database/19.3.0.0/prod_cdb)
(SID_NAME = prodcdb)
)
(SID_DESC =
(GLOBAL_DBNAME = prodcdb_dg02_DGMGRL) # 新增部分，名称为db_unique_name_DGMGRL
(ORACLE_HOME = /data/prd/oracle/database/19.3.0.0/prod_cdb)
(SID_NAME = prodcdb)
)
)
LISTENER =
(DESCRIPTION_LIST =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.3.226)(PORT = 1521))
)
)
)reload 监听生效，reload后应该能看到 _DGMGRL相关信息
lsnrctl reload
lsnrctl status3. 配置tnsnames.ora
三个节点均需配置
# add for DGMGRL
prodcdb_DGMGRL=
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.3.224)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = prodcdb_DGMGRL)
)
)
prodcdb_dg_DGMGRL=
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.3.225)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = prodcdb_dg_DGMGRL)
)
)
prodcdb_dg02_DGMGRL=
(DESCRIPTION =
(ADDRESS = (PROTOCOL = TCP)(HOST = 192.168.3.247)(PORT = 1521))
(CONNECT_DATA =
(SERVER = DEDICATED)
(SERVICE_NAME = prodcdb_dg02_DGMGRL)
)
)4. 清空远端LOG_ARCHIVE_DEST_n 信息
三个节点均需配置，这步开始，已有主从同步会中断。
ALTER SYSTEM SET LOG_ARCHIVE_DEST_2='';
ALTER SYSTEM SET LOG_ARCHIVE_DEST_3='';如果不清空，后面添加从库时会报错
DGMGRL> add database prodcdb as connect identifier is prodcdb_DGMGRL;
Error: ORA-16698: member has a LOG_ARCHIVE_DEST_n parameter with SERVICE attribute set Failed.
5. 修改dg_broker_config_file参数（可选）
可以用默认的路径，也可以自己指定（三个节点均需配置）。如果是RAC环境，把这个文件把到共享存储或者ASM中。
SQL> show parameter dg_broker_config_file
NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
dg_broker_config_file1 string /data/prd/oracle/database/19.3
.0.0/prod_cdb/dbs/dr1prodcdb.d
at
dg_broker_config_file2 string /data/prd/oracle/database/19.3
.0.0/prod_cdb/dbs/dr2prodcdb.d
at6. 启用BROKER
三个节点均需配置
alter system set dg_broker_start=true;7. 创建BROKER配置
任意节点执行即可，这里选择在主库（prodcdb_dg）执行
create configuration <配置名（随意）> as primary database is
dgmgrl
DGMGRL> connect sys/"xxxx"
DGMGRL> create configuration prodcdb_dgmgrl as primary database is prodcdb_dg connect identifier is prodcdb_dg_DGMGRL;8. 启用配置文件
DGMGRL>enable configuration
-- 查看配置文件
DGMGRL> show configuration9. 添加两个从节点
add database <备库db_unique_name> as connect identifier is
DGMGRL> add database prodcdb as connect identifier is prodcdb_DGMGRL;
DGMGRL> add database prodcdb_dg02 as connect identifier is prodcdb_dg02_DGMGRL;10. enable两个从库
DGMGRL> enable database prodcdb;
DGMGRL> enable database prodcdb_dg02;11. 查看配置及DB信息
至此配置完成，可以查看配置和从库信息
DGMGRL> show configuration
Configuration - prodcdb_dgmgrl
Protection Mode: MaxPerformance
Members:
prodcdb_dg - Primary database
prodcdb - Physical standby database
prodcdb_dg02 - Physical standby database
Fast-Start Failover: Disabled
Configuration Status:
SUCCESS (status updated 59 seconds ago)DGMGRL> show database prodcdb
Database - prodcdb
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 0 seconds ago)
Apply Lag: 0 seconds (computed 0 seconds ago)
Average Apply Rate: 6.00 KByte/s
Real Time Query: ON
Instance(s):
prodcdb
Database Status:
SUCCESS二、 利用DG Broker 进行 SwitchOver
- 首先检查下目标主库延迟
DGMGRL> show database prodcdb
Database - prodcdb
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 0 seconds ago)
Apply Lag: 0 seconds (computed 0 seconds ago)
Average Apply Rate: 6.00 KByte/s
Real Time Query: ON
Instance(s):
prodcdb- 切换变得简单无比，就一条命令
DGMGRL> switchover to prodcdb;
DGMGRL> switchover to prodcdb;
Performing switchover NOW, please wait...
Operation requires a connection to database "prodcdb"
Connecting ...
Connected to "prodcdb"
Connected as SYSDBA.
New primary database "prodcdb" is opening...
Operation requires start up of instance "prodcdb" on database "prodcdb_dg"
Starting instance "prodcdb"...
Connected to an idle instance.
ORACLE instance started.
Connected to "prodcdb_dg"
Database mounted.
Database opened.
Connected to "prodcdb_dg"
Switchover succeeded, new primary is "prodcdb"- 查看切换后配置信息
DGMGRL> show configuration
Configuration - prodcdb_dgmgrl
Protection Mode: MaxPerformance
Members:
prodcdb - Primary database
prodcdb_dg - Physical standby database
prodcdb_dg02 - Physical standby database
Fast-Start Failover: Disabled
Configuration Status:
SUCCESS (status updated 56 seconds ago)发现SwitchOver已经成功完成了
- 查看切换后DB信息
DGMGRL> show database prodcdb_dg
Database - prodcdb_dg
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 1 second ago)
Apply Lag: 0 seconds (computed 1 second ago)
Average Apply Rate: 23.00 KByte/s
Real Time Query: ON
Instance(s):
prodcdb
Database Status:
SUCCESS三、 利用DG Broker 进行 Failover
1. 模拟计划外切换场景
- 主库每秒执行一条insert语句
create table temp0315(a date);
begin
for i in 1 .. 1800 loop
insert into temp0315 values(sysdate);
commit;
DBMS_LOCK.SLEEP(1);
end loop;
end;
/- insert过程中执行shutdown abort强行关闭该库
shutdown abort- 尝试failover至从库
2. 开始failover
- 首先检查下目标主库延迟
DGMGRL> show database prodcdb_dg
Database - prodcdb_dg
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 59 seconds ago)
Apply Lag: 0 seconds (computed 59 seconds ago)
Average Apply Rate: 6.00 KByte/s
Real Time Query: ON
Instance(s):
prodcdb
Database Warning(s):
ORA-16857: member disconnected from redo source for longer than specified threshold
Database Status:
WARNING- failover切换也变得简单无比，就一条命令
DGMGRL> failover to prodcdb_dg;
DGMGRL> failover to prodcdb_dg
Performing failover NOW, please wait...
Failover succeeded, new primary is "prodcdb_dg"- 查看切换后配置信息
DGMGRL> show configuration
Configuration - prodcdb_dgmgrl
Protection Mode: MaxPerformance
Members:
prodcdb_dg - Primary database
Warning: ORA-16857: member disconnected from redo source for longer than specified threshold
prodcdb - Physical standby database (disabled)
ORA-16661: the standby database needs to be reinstated
prodcdb_dg02 - Physical standby database
Fast-Start Failover: Disabled
Configuration Status:
WARNING (status updated 93 seconds ago)- 查看切换后DB信息
DGMGRL> show database prodcdb_dg02
Database - prodcdb_dg02
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 1 second ago)
Apply Lag: 0 seconds (computed 1 second ago)
Average Apply Rate: 5.00 KByte/s
Real Time Query: ON
Instance(s):
prodcdb
Database Status:
SUCCESS补充：
如手工切换时failover有两类，使用DG Broker也有两种failover方法
- Complete Failover（默认）：尝试先将所有重做日志应用到备库，最大程度地减少数据丢失。
- Immediate Failover ：不再对备库进行日志应用，立刻进行切换。
DGMGRL> FAILOVER TO database-name;
# 或者
DGMGRL> FAILOVER TO database-name IMMEDIATE;四、 Failover后恢复主从关系
为使REINSTATE命令成功执行，故障转移之前必须已在原主库（新备库）上启用闪回，并且必须有足够的闪回和归档日志。
1. 启动到mount状态
如果有开机自启动的，startup过程中会报错 ORA-16649: possible failover to another database prevents this database from being opened，会发现只能起到mount状态，没关系，继续后面的操作。
startup mount2. 恢复主从关系
连接到代理配置中的任何数据库（要恢复的数据库除外）时，执行：
DGMGRL> reinstate database prodcdb;
Reinstating database "prodcdb", please wait...
Reinstatement of database "prodcdb" succeeded如果能完成，它将变为新主库的备库。如果失败，其状态将更改为 ORA-16795: the standby database needs to be re-created。那就没办法，只能重搭主从了。
3. 查看切换后配置信息
DGMGRL> show configuration
Configuration - prodcdb_dgmgrl
Protection Mode: MaxPerformance
Members:
prodcdb_dg - Primary database
prodcdb - Physical standby database
prodcdb_dg02 - Physical standby database
Fast-Start Failover: Disabled
Configuration Status:
SUCCESS (status updated 47 seconds ago)4. 查看切换后DB信息
DGMGRL> show database prodcdb
Database - prodcdb
Role: PHYSICAL STANDBY
Intended State: APPLY-ON
Transport Lag: 0 seconds (computed 1 second ago)
Apply Lag: 0 seconds (computed 1 second ago)
Average Apply Rate: 14.00 KByte/s
Real Time Query: ON
Instance(s):
prodcdb
Database Status:
SUCCESS参考
https://blog.csdn.net/shiyu1157758655/article/details/55504026
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Oracle DG 手动 SwitchOver & Failover，Failover后利用闪回恢复同步_Hehuyi_In的博客-CSDN博客
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