如何理解DRA特性，很多新手对此不是很清楚，为了帮助大家解决这个难题，下面小编将为大家详细讲解，有这方面需求的人可以来学习下，希望你能有所收获。
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DRA在遇到错误时会自动收集数据故障信息。此外，它还能预先检查故障。在此模式中，它可以在数据库进程发现损坏并发送错误消息之前检测和分析数据故障。
DRA的优势：
? Data Recovery Advisor can potentially detect, analyze, and repair data failures before a database process discovers the corruption and signals an error. Early warnings help limit damage caused by corruption.DRA可以觉察，分析，修复数据库错误
? Manually assessing symptoms of data failures and correlating them into a problem statement can be complex, error-prone, and time-consuming. Data Recovery Advisor automatically diagnoses failures, assesses their impact, and reports these findings to the user.
? Traditionally, users must manually determine repair options along with the repair impact. If multiple failures are present, then users must determine the right sequence of repair execution and try to consolidate repairs. In contrast, Data Recovery Advisor automatically determines the best repair options and runs checks to make sure that these options are feasible in your environment.
? Execution of a data repair can be complex and error-prone. If you choose an automated repair option, then Data Recovery Advisor executes the repair and verifies its success.
rman中包括以下命令都属于DRA特性
LIST FAILURE, ADVISE FAILURE, REPAIR FAILURE, and CHANGE FAILURE.
list failure 可以查看操作错误和造成的影响
advice failure查看修复的选项，一般都包含自动和手动
repair failure 在advice failure之后可以使用repaire failure修复错误
手动修改了user01.dbf文件
RMAN> list failure;
no failures found that match specification
没有发现错误
sqlplus连接数据库，查询表
SQL> select * from scott.emp;
select * from scott.emp
*
ERROR at line 1:
ORA-01116: error in opening database file 4
ORA-01110: data file 4: '/u01/app/oracle/oradata/test/users01.dbf'
ORA-27041: unable to open file
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
再次list failure
RMAN> list failure;
List of Database Failures
=========================
Failure ID Priority Status Time Detected Summary
---------- -------- --------- ------------------- -------
42 HIGH OPEN 2017-07-30 19:54:08 One or more non-system datafiles are missing
一个或多个非系统数据文件丢失
RMAN> advise failure;
List of Database Failures
=========================
Failure ID Priority Status Time Detected Summary
---------- -------- --------- ------------------- -------
42 HIGH OPEN 2017-07-30 19:54:08 One or more non-system datafiles are missing
analyzing automatic repair options; this may take some time
using channel ORA_DISK_1
analyzing automatic repair options complete
Mandatory Manual Actions
========================
1. If file /u01/app/oracle/oradata/test/users01.dbf was unintentionally renamed or moved, restore it
2. If you have an export of tablespace USERS, then drop and re-create the tablespace and import the data.
3. Contact Oracle Support Services if the preceding recommendations cannot be used, or if they do not fix the failures selected for repair
Optional Manual Actions
=======================
no manual actions available
Automated Repair Options
========================
no automatic repair options available
没有自动修复选项
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