PROTECTION_MODE is UNPROTECTED at standby database 分析

最新推荐文章于 2015-08-16 11:58:33 发布

转载最新推荐文章于 2015-08-16 11:58:33 发布 · 900 阅读

文章标签：

#UNPROTECTED #PROTECTION_LEVEL #DG #Oracle #PROTECTION_MODE

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本文探讨了Oracle DataGuard中出现的PROTECTION_MODE为UNPROTECTED的情况，并通过官方文档解释了其等同于MAXIMIZE PERFORMANCE模式的原因。

数据库版本

SQL> select * from v$version;

BANNER

--------------------------------------------------------------------------------------------------------------------------------

Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - 64bi

PL/SQL Release 10.2.0.1.0 - Production

CORE 10.2.0.1.0 Production

TNS for Linux: Version 10.2.0.1.0 - Production

NLSRTL Version 10.2.0.1.0 – Production

1、问题描述（data guard采用最大性能模式，但是备库的PROTECTION_MODE 竟是UNPROTECTED？）

主库

SQL> select DATABASE_ROLE,OPEN_MODE,PROTECTION_MODE from v$database;

DATABASE_ROLE OPEN_MODE PROTECTION_MODE

-------------------------------- -------------------- ----------------------------------------

PRIMARY READ WRITE MAXIMUM PERFORMANCE

备库

SQL> select DATABASE_ROLE,OPEN_MODE,PROTECTION_MODE from v$database;

DATABASE_ROLE OPEN_MODE PROTECTION_MODE

-------------------------------- -------------------- ----------------------------------------

PHYSICAL STANDBY MOUNTED UNPROTECTED

2、问题补充描述

备库日志正常应用，主库做DML操作，备库read only开启也可以看到DML的结果。说明此data guard本身是没有问题的。但是为什么备库的PROTECTION_MODE 会出现 UNPROTECTED呢？万分不解，在朋友的帮助下找到了关于这个问题的描述如下：

maximize_standby_db_clause

Use this clause to specify the level of protection for the data in your database environment. You specify this clause from the primary database, which must be mounted but not open.

Note:

The PROTECTED and UNPROTECTED keywords have been replaced for clarity but are still supported. PROTECTED is equivalent to TO MAXIMIZE PROTECTION. UNPROTECTED is equivalent to TO MAXIMIZE PERFORMANCE.