目录
一、下载镜像二、DG环境初始化三、主库做闪回数据库操作四、备库做闪回操作五、查询主备库是否实时同步六、总结
本文介绍一下，在DG环境中，若主库做了闪回数据库的操作后，备库如何通过flashback操作，继续和主库保持同步，而不用重新搭建DG。
主备库均已开启闪回数据库特性。
一、下载镜像
小麦苗DG环境的hub地址：
https://hub.docker.com/r/lhrbest/dg_pri_11.2.0.4/tags
https://hub.docker.com/r/lhrbest/dg_phy_11.2.0.4/tags
1nohup docker pull registry.cn-hangzhou.aliyuncs.com/lhrbest/dg_phy_11.2.0.4:1.0 &
2nohup docker pull registry.cn-hangzhou.aliyuncs.com/lhrbest/dg_pri_11.2.0.4:1.0 &
查看镜像：
1[root@docker36 ~]# docker images | grep dg
2registry.cn-hangzhou.aliyuncs.com/lhrbest/dg_phy_11.2.0.4 1.0 f2ea019fe540 15 hours ago 10.7GB
3registry.cn-hangzhou.aliyuncs.com/lhrbest/dg_pri_11.2.0.4 1.0 b7fae2029b40 15 hours ago 10.8GB
给镜像打tag：
1[root@docker36 ~]# docker tag registry.cn-hangzhou.aliyuncs.com/lhrbest/dg_phy_11.2.0.4:1.0 lhrbest/dg_phy_11.2.0.4:1.0
2[root@docker36 ~]# docker tag registry.cn-hangzhou.aliyuncs.com/lhrbest/dg_pri_11.2.0.4:1.0 lhrbest/dg_pri_11.2.0.4:1.0
3
4[root@docker36 ~]# docker images | grep dg
5lhrbest/dg_phy_11.2.0.4 1.0 f2ea019fe540 15 hours ago 10.7GB
6registry.cn-hangzhou.aliyuncs.com/lhrbest/dg_phy_11.2.0.4 1.0 f2ea019fe540 15 hours ago 10.7GB
7lhrbest/dg_pri_11.2.0.4 1.0 b7fae2029b40 15 hours ago 10.8GB
8registry.cn-hangzhou.aliyuncs.com/lhrbest/dg_pri_11.2.0.4 1.0 b7fae2029b40 15 hours ago 10.8GB
二、DG环境初始化
DG环境情况见下表：
| 项目 | 主库 | 物理备库 |
|---|---|---|
| db 类型 | 单实例 | 单实例 |
| db version | 11.2.0.4.0 | 11.2.0.4.0 |
| db 存储 | FS | FS |
| OS版本 | RHEL7.6 64位 | CentOS7.6 64位 |
| OS hostname | LHR11G | LHR11GDG |
| IP地址 | 192.168.68.68 | 192.168.68.69 |
| ORACLE_SID | LHR11G | LHR11GDG |
| db_name/GLOBAL_DBNAME | LHR11G | LHR11G |
| db_unique_name | LHR11G | LHR11GDG |
| TNS_NAME | LHR11G | LHR11GDG |
| 监听端口 | 1521 | 1521 |
| 映射的主机端口 | 1528 | 1529 |
| ORACLE_HOME | /u01/app/oracle/product/11.2.0.4/dbhome_1 | /u01/app/oracle/product/11.2.0.4/dbhome_1 |
| dbid | 2007947551 | 2007947551 |
1-- 创建DG的网络
2docker network create --subnet=192.168.68.0/16 mhalhr
3docker network inspect mhalhr
4
5-- 分别初始化主库和备库
6docker run -itd --name LHR11G -h LHR11G \
7 -p 1528:1521 -p 1128:1158 -p 228:22 -p 3398:3389 \
8 --network mhalhr --ip 192.168.68.68 \
9 --privileged=true \
10 lhrbest/dg_pri_11.2.0.4:1.0 init
11
12
13docker run -itd --name LHR11GDG -h LHR11GDG \
14 -p 1529:1521 -p 1129:1158 -p 229:22 -p 3399:3389 \
15 --network mhalhr --ip 192.168.68.69 \
16 --privileged=true \
17 lhrbest/dg_phy_11.2.0.4:1.0 init
18
19
20 -- 添加网卡
21docker network connect bridge LHR11G
22docker network connect bridge LHR11GDG
23
24
25-- 进入容器
26docker exec -it LHR11G bash
27docker exec -it LHR11GDG bash
28
29-- 分别启动主库、备库和监听
30su - oracle
31lsnrctl start
32sas
33startup
查询目前DG的同步情况：
1-- 查询目前DG部署
2DGMGRL> show configuration
3
4Configuration - LHR11G
5
6 Protection Mode: MaxPerformance
7 Databases:
8 LHR11G - Primary database
9 LHR11GDG - Physical standby database
10
11Fast-Start Failover: DISABLED
12
13Configuration Status:
14SUCCESS
15
16-- 主库
17SYS@LHR11G> select flashback_on,db_unique_name,database_role from v$database;
18
19FLASHBACK_ON DB_UNIQUE_NAME DATABASE_ROLE
20------------------------------------ ------------------------------------------------------------ --------------------------------
21YES LHR11G PRIMARY
22
23SYS@LHR11G> alter system switch logfile ;
24
25System altered.
26
27SYS@LHR11G> create table lhr.emp1 as select * from scott.emp;
28
29Table created.
30
31SYS@LHR11G> select count(*) from lhr.emp1;
32
33 COUNT(*)
34----------
35 14
36
37SYS@LHR11G> select current_scn from v$database;
38
39CURRENT_SCN
40-----------
41 1363331
42
43-- 备库
44
45SYS@LHR11GDG> select flashback_on,db_unique_name,database_role from v$database;
46
47FLASHBACK_ON DB_UNIQUE_NAME DATABASE_ROLE
48------------------------------------ ------------------------------------------------------------ --------------------------------
49YES LHR11GDG PHYSICAL STANDBY
50
51
52SYS@LHR11GDG> select count(*) from lhr.emp1;
53
54 COUNT(*)
55----------
56 14
57
58SYS@LHR11GDG> select current_scn from v$database;
59
60CURRENT_SCN
61-----------
62 1363340
三、主库做闪回数据库操作
1SYS@LHR11G> select current_scn from v$database;
2
3CURRENT_SCN
4-----------
5 1363438
6
7SYS@LHR11G> create table lhr.emp2 as select * from scott.emp;
8
9Table created.
10
11SYS@LHR11G> startup force mount
12ORACLE instance started.
13
14Total System Global Area 325685248 bytes
15Fixed Size 2252944 bytes
16Variable Size 188747632 bytes
17Database Buffers 130023424 bytes
18Redo Buffers 4661248 bytes
19Database mounted.
20SYS@LHR11G> flashback database to scn 1363438;
21
22Flashback complete.
23
24SYS@LHR11G> alter database open resetlogs;
25
26Database altered.
27
28SYS@LHR11G> create table lhr.emp3 as select * from scott.emp;
29
30Table created.
四、备库做闪回操作
1SYS@LHR11GDG> select count(*) from lhr.emp3;
2select count(*) from lhr.emp3
3 *
4ERROR at line 1:
5ORA-00942: table or view does not exist
6
7
8SYS@LHR11GDG> select count(*) from lhr.emp2;
9
10 COUNT(*)
11----------
12 14
13
14SYS@LHR11GDG> select current_scn from v$database;
15
16CURRENT_SCN
17-----------
18 1363462
19
20SYS@LHR11GDG> select current_scn from v$database;
21
22CURRENT_SCN
23-----------
24 1363462
可见，主备关系已经断掉。接下来，对备库进行闪回。
1SYS@LHR11GDG> startup force mount
2ORACLE instance started.
3
4Total System Global Area 346562560 bytes
5Fixed Size 2253144 bytes
6Variable Size 209718952 bytes
7Database Buffers 130023424 bytes
8Redo Buffers 4567040 bytes
9Database mounted.
10SYS@LHR11GDG> flashback database to scn 1363438;
11flashback database to scn 1363438
12*
13ERROR at line 1:
14ORA-38754: FLASHBACK DATABASE not started; required redo log is not available
15ORA-38762: redo logs needed for SCN 1363064 to SCN 1363438
16ORA-38761: redo log sequence 9 in thread 1, incarnation 7 could not be accessed
17
18SYS@LHR11GDG> select * from v$flashback_database_log;
19
20OLDEST_FLASHBACK_SCN OLDEST_FLASHBACK_TI RETENTION_TARGET FLASHBACK_SIZE ESTIMATED_FLASHBACK_SIZE
21-------------------- ------------------- ---------------- -------------- ------------------------
22 1232930 2020-10-27 16:21:36 1440 104857600 0
23
24SYS@LHR11GDG> flashback database to scn 1361000;
25
26Flashback complete.
27
28SYS@LHR11GDG> alter database open;
29
30Database altered.
31
32SYS@LHR11GDG> alter database recover managed standby database using current logfile disconnect from session;
33
34Database altered.
35
36SYS@LHR11GDG> select count(*) from lhr.emp3;
37
38 COUNT(*)
39----------
40 14
41
42SYS@LHR11GDG> select count(*) from lhr.emp2;
43select count(*) from lhr.emp2
44 *
45ERROR at line 1:
46ORA-00942: table or view does not exist
47
48
49SYS@LHR11GDG> select current_scn from v$database;
50
51CURRENT_SCN
52-----------
53 1365917
五、查询主备库是否实时同步
1[oracle@lhr11g ~]$ dgmgrl /
2DGMGRL for Linux: Version 11.2.0.4.0 - 64bit Production
3
4Copyright (c) 2000, 2009, Oracle. All rights reserved.
5
6Welcome to DGMGRL, type "help" for information.
7Connected.
8DGMGRL> show configuration
9
10Configuration - LHR11G
11
12 Protection Mode: MaxPerformance
13 Databases:
14 LHR11G - Primary database
15 LHR11GDG - Physical standby database
16
17Fast-Start Failover: DISABLED
18
19Configuration Status:
20SUCCESS
21
22
23-- 主库建表
24SYS@LHR11G> create table lhr.emp4 as select * from scott.emp;
25
26Table created.
27
28-- 备库查询
29SYS@LHR11GDG> select count(*) from lhr.emp4;
30
31 COUNT(*)
32----------
33 14
34
DG环境恢复正常。
六、总结
1、在DG环境中，建议对主库和备库都开启闪回数据库的特性，并且设置比较大的闪回恢复区（db_recovery_file_dest_size）。
2、在DG环境中，若主库做了闪回数据库的操作，那么备库必须做相关的闪回操作才能恢复DG的同步关系。
本文结束。
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