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【DataGuard】Oracle 11g DataGuard 新特性之 Snapshot Standby Database

原创 Oracle 作者：海星星hktk 时间：2014-08-24 14:05:58 5 删除 编辑
Oracle 11g DataGuard 新特性之 Snapshot Standby Database



Oracle 11g DataGuard 的Snapshot Standby数据库功能，可以让物理备库从只读状态 切换到可读写状态。
在snapshot standby状态下，备库可以进行读写操作，同时备库还会正常接收主库的归档和日志信息，但不会应用这些redo日志。
当备库读写状态下任务完成后，还可以从Snapshot Standby数据库角色切换回Physical standby备库角色，恢复与主库数据同步。
切换回物理备库后，在Snapshot standby状态下写入备库的数据将不再存在。

【实验环境】
Red Hat Enterprise Linux Server release 5.4
Oracle Database 11g Enterprise Edition Release 11.2.0.3.0

【DG主库、物理备库结构信息】




【实验过程】

主库 Primary database：绿色
物理备库 Physical standby database:黄色


1、切换前准备

 1.1、查看当前备库模式

sys@DGDB>select database_role, open_mode, protection_mode, protection_level from v$database;

 

1.2、主备库查看测试表信息






1.3、确认备库闪回区已设置

未设置闪回区报错



设置闪回区后查看

sys@DGDB>show parameter db_recovery

 

1.4、备库取消日志应用

在日志应用状态转换报错


备库取消日志应用

sys@DGDB>alter database recover managed standby database cancel;

sys@DGDB>select database_role, open_mode, protection_mode, protection_level from v$database;


 

2、physical standby 切换为 snapshot standby

2.1、备库转换为snapshot standby


sys@DGDB>alter database convert to snapshot standby;   -- 转化成 snapshot standby

查看当前备库状态 snapshot standby
sys@DGDB>select database_role, open_mode, protection_mode, protection_level from v$database;

 

转换过程中告警日志

Sun Aug 24 01:18:07 2014

alter database convert to snapshot standby

Starting background process RVWR

Sun Aug 24 01:18:07 2014

RVWR started with pid=27, OS id=17153

Allocated 3981120 bytes in shared pool for flashback generation buffer

Created guaranteed restore point SNAPSHOT_STANDBY_REQUIRED_08/24/2014 01:18:07

krsv_proc_kill: Killing 3 processes (all RFS)

All dispatchers and shared servers shutdown

CLOSE: killing server sessions.

CLOSE: all sessions shutdown successfully.

Sun Aug 24 01:18:10 2014

SMON: disabling cache recovery

Begin: Standby Redo Logfile archival

End: Standby Redo Logfile archival

RESETLOGS after incomplete recovery UNTIL CHANGE 1216097

Resetting resetlogs activation ID 2198976699 (0x8311b8bb)

Online log /u02/oradata/sh/redo01.log: Thread 1 Group 1 was previously cleared

Online log /u02/oradata/sh/redo02.log: Thread 1 Group 2 was previously cleared

Online log /u02/oradata/sh/redo03.log: Thread 1 Group 3 was previously cleared

Standby became primary SCN: 1216095

Sun Aug 24 01:18:11 2014

Setting recovery target incarnation to 3

CONVERT TO SNAPSHOT STANDBY: Complete - Database mounted as snapshot standby

Completed: alter database convert to snapshot standby

 

2.2、snapshot standby开库，可读写


sys@DGDB>alter database open;

sys@DGDB>select database_role, open_mode, protection_mode, protection_level from v$database;


 

2.3、对测试表进行插入操作

现在可以 读写操作 standby database

sys@DGDB>insert into lvxinghao.test select * from scott.emp;

sys@DGDB>select count(*) from lvxinghao.test;


 

3、snapshot standby 切回 日志应用状态

3.1、备库重启到mount状态

idle>startup mount force;

idle>select database_role, open_mode, protection_mode, protection_level from v$database;



3.2、备库由snapshot standby 切换为 physical standby

idle>alter database convert to physical standby;



 

切换过程中跟踪日志

Sun Aug 24 01:26:09 2014

alter database convert to physical standby

ALTER DATABASE CONVERT TO PHYSICAL STANDBY (SH)

Flashback Restore Start

Flashback Restore Complete

Drop guaranteed restore point

Stopping background process RVWR

Deleted Oracle managed file /u01/app/oracle/fast_recovery_area/DGDB/SHANGHAI/flashback/o1_mf_9zlxdhmc_.flb

Deleted Oracle managed file /u01/app/oracle/fast_recovery_area/DGDB/SHANGHAI/flashback/o1_mf_9zlxdl5k_.flb

Guaranteed restore point  dropped

Clearing standby activation ID 2202357444 (0x83454ec4)

The primary database controlfile was created using the

'MAXLOGFILES 16' clause.

There is space for up to 13 standby redo logfiles

Use the following SQL commands on the standby database to create

standby redo logfiles that match the primary database:

ALTER DATABASE ADD STANDBY LOGFILE 'srl1.f' SIZE 52428800;

ALTER DATABASE ADD STANDBY LOGFILE 'srl2.f' SIZE 52428800;

ALTER DATABASE ADD STANDBY LOGFILE 'srl3.f' SIZE 52428800;

ALTER DATABASE ADD STANDBY LOGFILE 'srl4.f' SIZE 52428800;

Shutting down archive processes

Archiving is disabled

Sun Aug 24 01:26:09 2014

ARCH shutting down

ARC3: Archival stopped

Sun Aug 24 01:26:09 2014

ARCH shutting down

ARC2: Archival stopped

Sun Aug 24 01:26:09 2014

ARCH shutting down

ARC1: Archival stopped

Sun Aug 24 01:26:09 2014

ARCH shutting down

ARC0: Archival stopped

Completed: alter database convert to physical standby

 
切换完成后实例处于started状态

sys@DGDB>select instance_name,status from v$instance;



3.3、重启备库到mount状态，查看当前备库角色


sys@DGDB>startup mount force;

sys@DGDB>select database_role, open_mode, protection_mode, protection_level from v$database;



3.4、备库开库，查看测试表

sys@DGDB>alter database open;


sys@DGDB>select database_role, open_mode, protection_mode, protection_level from v$database;


 

查看测试表 条数不再是24条，而是恢复到切换前与主库相同的10条

 

3.5、备库上Real-time Apply 方式应用日志


sys@DGDB>alter database recover managed standby database using current logfile disconnect;


 

 
【实验总结】

1、切换Snapshot standby前，物理备库需设置快速回复区db_recovery_file_dest。
2、物理备库切换为Snapshot standby状态前，需取消备库的日志应用。

3、物理备库切换为Snapshot standby时，会创建一个restore point，当需要从snapshot standby状态切回原来的状态时，会回到这个restore point的状态，期间在snapshot standby 的备库上写入的数据将不再存在。


吕星昊
2014.8.24

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海星星hktk
专家姓名：吕星昊
Oracle OCM 讲师。达梦认证讲师DM8-DCI。OceanBase认证讲师OBCI。拥有10g、12c OCM，OBCP等认证证书。曾任 Oracle WDP 注册OCM讲师，已培养Oracle OCP认证专家2000余人，培养Oracle OCM认证大师360余人。

注册时间：2014-02-08

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