Oracle数据恢复顾问(DRA)使用测试

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_1311249797.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_1311249797.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_1311249797.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

  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 00004 to /u01/V112_oradata/users01.dbf
  channel ORA_DISK_1: restoring datafile 00005 to /u01/V112_oradata/test01.dbf
  channel ORA_DISK_1: reading from backup piece
  /u01/temp/flash_areas/V112/V112/backupset/2013_08_21/o1_mf_nnndf_TAG20130821T100251_919l4f2p_.bkp
  channel ORA_DISK_1: piece
  handle=/u01/temp/flash_areas/V112/V112/backupset/2013_08_21/o1_mf_nnndf_TAG20130821T100251_919l4f2p_.bkp
  tag=TAG20130821T100251
  channel ORA_DISK_1: restored backup piece 1
  channel ORA_DISK_1: restore  complete, elapsed time: 00:00:35
  Finished restore at 21-AUG-13

  Starting recover at 21-AUG-13
  using channel ORA_DISK_1

  archived log for thread 1 with sequence 79 is already on disk as file
  /u01/temp/flash_areas/V112/V112/archivelog/2013_08_21/o1_mf_1_79_919lm6y2_.arc
  channel ORA_DISK_1: starting archived log restore to default destination
  channel ORA_DISK_1: restoring archived log
  archived log thread=1 sequence=77
  channel ORA_DISK_1: restoring archived log
  archived log thread=1 sequence=78
  channel ORA_DISK_1: reading from backup piece
  /u01/temp/flash_areas/V112/V112/backupset/2013_08_21/o1_mf_annnn_TAG20130821T101028_919llo3n_.bkp
  channel ORA_DISK_1: piece
  handle=/u01/temp/flash_areas/V112/V112/backupset/2013_08_21/o1_mf_annnn_TAG20130821T101028_919llo3n_.bkp
  tag=TAG20130821T101028
  channel ORA_DISK_1: restored backup piece 1
  channel ORA_DISK_1: restore complete, elapsed time: 00:00:01
  archived log file name=/u01/temp/flash_areas/V112/V112/archivelog/2013_08_21/o1_mf_1_77_919ltj5h_.arc
  thread=1 sequence=77
  channel default: deleting archived log(s)
  archived log file name=/u01/temp/flash_areas/V112/V112/archivelog/2013_08_21/o1_mf_1_77_919ltj5h_.arc
  RECID=50 STAMP=824033680
  archived log file name=/u01/temp/flash_areas/V112/V112/archivelog/2013_08_21/o1_mf_1_78_919ltj7o_.arc
  thread=1 sequence=78
  channel default: deleting archived log(s)
  archived log file name=/u01/temp/flash_areas/V112/V112/archivelog/2013_08_21/o1_mf_1_78_919ltj7o_.arc
  RECID=51 STAMP=824033680
  media recovery complete, elapsed  time: 00:00:00
  Finished recover at 21-AUG-13

  sql statement: alter database      datafile 4, 5 online
  repair failure complete 

一旦成功完成修复脚本,这个问题应该得到解决,并且select语句返回预期的结果:
 
 SQL> select * from emp;
  EMPNO ENAME    JOB      MGR  HIREDATE  SAL  COMM  DEPTNO
  ----- -------- --------- ----- --------- ---- ----- ------
    7900 JAMES    CLERK    7698  03-DEC-81  950      30
    7902 FORD    ANALYST  7566  03-DEC-81 3000      20
    7934 MILLER  CLERK    7782  23-JAN-82 1300      10

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