关于DRA的官方描述：

The simplest way to diagnose and repair database problems is to use the Data Recovery Advisor. This Oracle Database tool provides an infrastructure for diagnosing persistent data failures, presenting repair options to the user, and automatically executing repairs.

下面我们来做一个小实验来实际体会下DRA的便利性：

rman登录到目标数据库

我们这里模拟丢失了一个数据文件

观察DRA是如何恢复数据库的

1.rman登录到目标数据库

[oracle@JY-DB BACKUP]$ rman target /

Recovery Manager: Release 11.2.0.4.0 - Production on Wed Aug 5 11:15:12 2015

Copyright (c) 1982, 2011, Oracle and/or its affiliates. All rights reserved.

connected to target database: JYZHAO (DBID=2463175424, not open)

RMAN> LIST FAILURE;

using target database control file instead of recovery catalog

no failures found that match specification

可以看到目前数据库没有找到需要恢复的匹配项。

2.我们这里模拟丢失了一个数据文件

#2.1 正常关库

SQL> shutdown immediate

Database closed.

Database dismounted.

ORACLE instance shut down.

#2.2 删除数据文件+DATA1/jyzhao/datafile/dbs_d_jingyu.259.886871319

#直接删除数据文件会报错

ASMCMD> rm DBS_D_JINGYU.259.886871319

ORA-15032: not all alterations performed

ORA-15028: ASM file '+DATA1/jyzhao/datafile/DBS_D_JINGYU.259.886871319' not dropped; currently being accessed (DBD ERROR: OCIStmtExecute)

#数据库关闭后删除成功

ASMCMD> rm DBS_D_JINGYU.259.886871319

ASMCMD>

#2.3 尝试打开数据库报错

SQL> startup

ORACLE instance started.

Total System Global Area 1620115456 bytes

Fixed Size 2253704 bytes

Variable Size 905972856 bytes

Database Buffers 704643072 bytes

Redo Buffers 7245824 bytes

Database mounted.

ORA-01157: cannot identify/lock data file 15 - see DBWR trace file

ORA-01110: data file 15: '+DATA1/jyzhao/datafile/dbs_d_jingyu.259.886871319'

3.观察DRA是如何恢复数据库的

3.1 LIST FAILURE;

RMAN> LIST FAILURE;

List of Database Failures

=========================

Failure ID Priority Status Time Detected Summary

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

4042 HIGH OPEN 05-AUG-15 One or more non-system datafiles are missing

3.2 ADVISE FAILURE;

RMAN> ADVISE FAILURE;

List of Database Failures

=========================

Failure ID Priority Status Time Detected Summary

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

4042 HIGH OPEN 05-AUG-15 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=25 device type=DISK

analyzing automatic repair options complete

Mandatory Manual Actions

========================

no manual actions available

Optional Manual Actions

=======================

1. If file +DATA1/jyzhao/datafile/dbs_d_jingyu.259.886871319 was unintentionally renamed or moved, restore it

2. Try flush redo using ALTER SYSTEM FLUSH REDO TO 'standby name' command. Then perform a Data Guard role change (failover). Available standbys: jyzhao_s.

Automated Repair Options

========================

Option Repair Description

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

1 Restore and recover datafile 15

Strategy: The repair includes complete media recovery with no data loss

Repair script: /u01/app/oracle/diag/rdbms/jyzhao/jyzhao/hm/reco_4099084102.hm

3.3 REPAIR FAILURE;

RMAN> REPAIR FAILURE;

Strategy: The repair includes complete media recovery with no data loss

Repair script: /u01/app/oracle/diag/rdbms/jyzhao/jyzhao/hm/reco_4099084102.hm

contents of repair script:

# restore and recover datafile

restore datafile 15;

recover datafile 15;

sql 'alter database datafile 15 online';

Do you really want to execute the above repair (enter YES or NO)? yes

executing repair script

Starting restore at 05-AUG-15

using channel ORA_DISK_1

channel ORA_DISK_1: starting datafile backup set restore

channel ORA_DISK_1: specifying datafile(s) to restore from backup set

channel ORA_DISK_1: restoring datafile 00015 to +DATA1/jyzhao/datafile/dbs_d_jingyu.259.886871319

channel ORA_DISK_1: reading from backup piece /u01/app/oracle/product/11.2.0/db_1/dbs/arch/JYZHAO/backupset/2015_08_05/o1_mf_nnndf_TAG20150805T102730_bw2x4m1l_.bkp

channel ORA_DISK_1: piece handle=/u01/app/oracle/product/11.2.0/db_1/dbs/arch/JYZHAO/backupset/2015_08_05/o1_mf_nnndf_TAG20150805T102730_bw2x4m1l_.bkp tag=TAG20150805T102730

channel ORA_DISK_1: restored backup piece 1

channel ORA_DISK_1: restore complete, elapsed time: 00:00:01

Finished restore at 05-AUG-15

Starting recover at 05-AUG-15

using channel ORA_DISK_1

starting media recovery

media recovery complete, elapsed time: 00:00:00

Finished recover at 05-AUG-15

sql statement: alter database datafile 15 online

repair failure complete

Do you want to open the database (enter YES or NO)? yes

database opened

RMAN>

到此，使用DRA自动恢复完毕并成功打开数据库。