来了解Oracle数据恢复顾问（DRA）在这种情况下是如何帮助我们的吧！数据恢复顾问（Data Recovery Advisor）是一款Oracle数据库工
曾经处理过硬盘上数据损坏或者数据丢失的问题么？结果，尽管你还处在诊断和分析问题发生的阶段，最终用户和经理已经联系你，并且希望知道解决问题的大概时间（eta）了。你是否希望拥有一个简单，并且更为重要的是，快速的方法来诊断和修复这种类型的故障呢？
继续阅读，来了解Oracle数据恢复顾问（DRA）在这种情况下是如何帮助我们的吧！
数据恢复顾问（Data Recovery Advisor）是一款Oracle数据库工具。该工具会自动诊断数据故障，确定并提出相应修复方案，并执行客户要求的修复。以上修复是基于数据故障是一个硬盘上持久性数据的损坏或者丢失。
数据恢复顾问会在遇到问题时，，自动采集数据故障信息，并且，协助执行对于故障的修复。你可以手动修复一个数据故障，或者要求数据恢复顾问来为你执行修复动作。
DRA可以通过企业管理器（EM）Grid Control和/或者恢复管理器（RMAN）来访问。本文将概述在RMAN中使用的命令。
在RMAN中，有四种DRA的命令：
•List Failure - 列出先前执行过的故障评估结果。可能的话，重新验证现有故障并关闭它们。
•Advise Failure - 提出手动和自动修复方案。
•Repair Failure - 通过运行由ADVISE FAILURE建议的最佳修复方案来自动修复故障。完成之后会重新验证现有故障。
•Change Failure - 使你可以改变故障的状态。
例如：下面的步骤有关于一次事故，当一个数据文件已经从操作系统上删除，数据库报告错误。
一个select语句执行失败，并报出如下错误：
SQL> select * from emp;
select * from emp
*
ERROR at line 1:
ORA-01116: error in opening database file 4
ORA-01110: data file 4: '/u01/V112_oradata/users01.dbf'
ORA-27041: unable to open file
Linux Error: 2: No such file or directory
Additional information: 3
DRA命令‘list failure’提供了此次问题的详细信息：
Recovery Manager: Release 11.2.0.3.0 - Production on Wed Aug 21 10:12:36 2013
Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.
connected to target database: V112 (DBID=2335388877)
RMAN> list failure;
using target database control file instead of recovery catalog
List of Database Failures
=========================
Failure ID Priority Status Time Detected Summary
---------- -------- --------- --------- --------------------------------------------
82 HIGH OPEN 21-AUG-13 One or more non-system datafiles are missing
做为DRA的下一步操作，使用命令'advise failure'，获得修复该问题的建议方案：
RMAN> advise failure;
List of Database Failures
=========================
Failure ID Priority Status Time Detected Summary
---------- -------- --------- ------------- -------
82 HIGH OPEN 21-AUG-13 One or more non-system datafiles are missing
analyzing automatic repair options; this may take some time
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=28 device type=DISK
analyzing automatic repair options complete
Mandatory Manual Actions
========================
no manual actions available
Optional Manual Actions
=======================
1. If file /u01/V112_oradata/users01.dbf was unintentionally renamed or moved, restore it
2. If file /u01/V112_oradata/test01.dbf was unintentionally renamed or moved, restore it
Automated Repair Options
========================
Option Repair Description
------ ------------------
1 Restore and recover datafile 4; Restore and recover datafile 5
Strategy: The repair includes complete media recovery with no data loss
Repair script: /u02/app/oracle/diag/rdbms/v112/V112/hm/reco_1311241249797.hm
DRA信息中描述了，2个数据文件的缺失，并且建议还原和恢复。
如前所述，DRA可以修复故障。执行修复脚本之前，可以预览所建议的命令：
RMAN> repair failure preview;
Strategy: The repair includes complete media recovery with no data loss
Repair script: /u02/app/oracle/diag/rdbms/v112/V112/hm/reco_1311241249797.hm
contents of repair script:
# restore and recover datafile
sql 'alter database datafile 4, 5 offline';
restore datafile 4, 5;
recover datafile 4, 5;
sql 'alter database datafile 4, 5 online';
现在，你可以决定是否手动运行上面的脚本或让DRA来执行修复：
RMAN> repair failure;
Strategy: The repair includes complete media recovery with no data loss
Repair script: /u02/app/oracle/diag/rdbms/v112/V112/hm/reco_1311241249797.hm
contents of repair script:
# restore and recover datafile
sql 'alter database datafile 4, 5 offline';
restore datafile 4, 5;
recover datafile 4, 5;
sql 'alter database datafile 4, 5 online';
Do you really want to execute the above repair (enter YES or NO)? yes
executing repair script
sql statement: alter database datafile 4, 5 offline
Starting restore at 21-AUG-13
using channel ORA_DISK_1
