RMAN进行基于数据块的恢复

从ORACLE9i开始，rman支持基于数据库的恢复，这一功能有很大的好处，既不影响业务，甚至不影响有坏块的数据文件，恢复可以是在线恢复。但是恢复是完全恢复，所以要求完整的备份。

下面测试：

1. 对数据库进行完整备份

   Rman>backup database;

2. 破坏数据

   参看日志《RMAN进行基于数据块的恢复》

3. 使用rman验证数据文件

   RMAN> backup validate datafile 5;

   Starting backup at 29-AUG-14

   using target database control file instead of recovery catalog

   allocated channel: ORA_DISK_1

   channel ORA_DISK_1: sid=159 devtype=DISK

   allocated channel: ORA_DISK_2

   channel ORA_DISK_2: sid=139 devtype=DISK

   channel ORA_DISK_1: starting full datafile backupset

   channel ORA_DISK_1: specifying datafile(s) in backupset

   input datafile fno=00005 name=/opt/oracle/oradata/orcla/xzsp.dbf

   channel ORA_DISK_1: backup set complete, elapsed time: 00:00:07

   Finished backup at 29-AUG-14

   警告日志和数据库中都会记录损坏的数据，如下

   SQL> select * from v$database_block_corruption ;

   FILE# BLOCK# BLOCKS CORRUPTION_CHANGE# CORRUPTIO

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

   5 49316 1 0 CORRUPT

4. 通过备份基于数据快级的恢复

   RMAN> blockrecover datafile 5 block 49316 from backupset;

   Starting blockrecover at 29-AUG-14

   using channel ORA_DISK_1

   using channel ORA_DISK_2

    

   channel ORA_DISK_1: restoring block(s)

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

   restoring blocks of datafile 00005

   channel ORA_DISK_1: reading from backup piece /opt/oracle/flash_recovery_area1/ORCLA/backupset/2014_08_29/o1_mf_nnndf_TAG20140829T032828_9zz0px68_.bkp

   channel ORA_DISK_1: restored block(s) from backup piece 1

   piece handle=/opt/oracle/flash_recovery_area1/ORCLA/backupset/2014_08_29/o1_mf_nnndf_TAG20140829T032828_9zz0px68_.bkp tag=TAG20140829T032828

   channel ORA_DISK_1: block restore complete, elapsed time: 00:00:26

    

   starting media recovery

    

   archive log thread 1 sequence 5 is already on disk as file /opt/oracle/flash_recovery_area1/ORCLA/archivelog/2014_08_29/o1_mf_1_5_9zz2mqwo_.arc

   archive log thread 1 sequence 6 is already on disk as file /opt/oracle/flash_recovery_area1/ORCLA/archivelog/2014_08_29/o1_mf_1_6_9zz2v3jj_.arc

   archive log thread 1 sequence 7 is already on disk as file /opt/oracle/flash_recovery_area1/ORCLA/archivelog/2014_08_29/o1_mf_1_7_9zz3hfff_.arc

   media recovery complete, elapsed time: 00:00:01

   Finished blockrecover at 29-AUG-14

5. 清楚坏块记录

   SQL> select * from v$database_block_corruption ;

   FILE# BLOCK# BLOCKS CORRUPTION_CHANGE# CORRUPTIO

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

   5 49316 1 0 CORRUPT

   RMAN> backup validate datafile 5;

   Starting backup at 29-AUG-14

   using channel ORA_DISK_1

   using channel ORA_DISK_2

   channel ORA_DISK_1: starting full datafile backupset

   channel ORA_DISK_1: specifying datafile(s) in backupset

   input datafile fno=00005 name=/opt/oracle/oradata/orcla/xzsp.dbf

   channel ORA_DISK_1: backup set complete, elapsed time: 00:00:03

   Finished backup at 29-AUG-14

   SQL> select * from v$database_block_corruption ;

    

   no rows selected

    

   注意：

   但有些情况下,BLOCKRECOVER未必可以恢复得了:

   [oracle@ique datafile]$ sqlplus mayp/mayp

   SQL*Plus: Release 10.1.0.5.0 – Production on Mon Jul 14 17:08:06 2008

   Copyright (c) 1982, 2005, Oracle. All rights reserved.

   Connected to:

   Oracle Database 10g Enterprise Edition Release 10.1.0.5.0 – Production

   With the Partitioning, OLAP and Data Mining options

   SQL> select count(*) from mssm;

   select count(*) from mssm

   *

   ERROR at line 1:

   ORA-01578: ORACLE data block corrupted (file # 5, block # 9)

   ORA-01110: data file 5: '/data/mayp/MAYP/datafile/o1_mf_mssm_4789hznr_.dbf'

   [oracle@ique datafile]$ rman target /

   Recovery Manager: Release 10.1.0.5.0 – Production

   Copyright (c) 1995, 2004, Oracle. All rights reserved.

   connected to target database: MAYP (DBID=412172232)

   RMAN> blockrecover datafile 5 block 9;

   Starting blockrecover at 14-JUL-08

   using target database controlfile instead of recovery catalog

   allocated channel: ORA_DISK_1

   channel ORA_DISK_1: sid=378 devtype=DISK

   RMAN-00571: ===========================================================

   RMAN-00569: =============== ERROR MESSAGE STACK FOLLOWS ===============

   RMAN-00571: ===========================================================

   RMAN-03002: failure of blockrecover command at 07/14/2008 17:08:37

   ORA-01455: converting column overflows integer datatype

   RMAN-06010: error while looking up datafile: 5

   这个块损坏已经严重破坏了数据的存放规律,发生了逻辑损坏,所以blockrecover没办法恢复,必须首先restore这个文件然后通过recvoer命令进行恢复.

   通过常规方法恢复这个错误:

   RMAN> sql 'alter database datafile 5 offline';

   sql statement: alter database datafile 5 offline

   RMAN> restore datafile 5;

   Starting restore at 14-JUL-08

   using channel ORA_DISK_1

   channel ORA_DISK_1: starting datafile backupset restore

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

   restoring datafile 00005 to /data/mayp/MAYP/datafile/o1_mf_mssm_4789hznr_.dbf

   channel ORA_DISK_1: restored backup piece 1

   piece handle=/home/oracle/product/10.2/dbs/full_2_MAYP.rman tag=TAG20080714T152854

   channel ORA_DISK_1: restore complete

   Finished restore at 14-JUL-08

   RMAN> recover datafile 5;

   Starting recover at 14-JUL-08

   using channel ORA_DISK_1

   starting media recovery

   media recovery complete

   Finished recover at 14-JUL-08

   RMAN> sql 'alter database datafile 5 online';

   sql statement: alter database datafile 5 online

   RMAN> exit

   BLOCKRECOVER 的使用限制:

   1、数据库必须在ARCHIVELOG模式下才可以使用这个功能;

   2、数据库必须是mount或open状态;

   3、不能对一个offline的datafile进行BLOCKRECOVER;

   4、blcokrecover需要通过一个full backups 恢复datra block,不能使用incremental backups进行错误恢复;

   5、blockrecover不能跨越archivelog丢失或损坏,也就是说在恢复的过程中,不能丢失需要的归档日志;

   6、blockrecover不能恢复逻辑坏块,逻辑坏块必须首先restore损坏的数据文件,然后在用recover进行恢复;

   7、blockrecvoer不能恢复file header block.(block=1).