使用RMAN备份与恢复数据库（10）——修复损坏的数据块

使用RMAN备份与恢复数据库（10）——修复损坏的数据块

如果某个数据文件正常，但数据文件中的某些数据块损坏，可以使用RMAN修复。

一、模拟数据块损坏

1、新建表空间data03

新建一个表空间data03，文件大小5M。

SQL> create tablespace data03 datafile '/usr/local/oradata/orcl/data03.dbf' size 2m;

Tablespace created.

Elapsed: 00:00:00.40
SQL> select name from v$datafile;

NAME
-----------------------------------------------------------------------------------
/usr/local/oradata/orcl/system01.dbf
/usr/local/oradata/orcl/sysaux01.dbf
/usr/local/oradata/orcl/undotbs01.dbf
/usr/local/oradata/orcl/users01.dbf
/usr/local/oradata/orcl/data01.dbf
/usr/local/oradata/orcl/data02.dbf
/usr/local/oradata/orcl/data03.dbf

2、在表空间data03中创建表

在表空间中创建一个scott.t_emp表，并添加数据，充满整个表空间。

SQL> create table scott.t_emp tablespace data03 as select * from scott.e02 where rownum<20000;
Table created.

3、使用RMAN备份表空间

RMAN> recover tablespace data03;

Starting recover at 2020-04-12 14:45:55
using channel ORA_DISK_1
using channel ORA_DISK_2

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

Finished recover at 2020-04-12 14:45:56

RMAN> backup tablespace data03 format '/home/oracle/rmanbak/data03.bak';

Starting backup at 2020-04-12 14:47:50
using channel ORA_DISK_1
using channel ORA_DISK_2
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00007 name=/usr/local/oradata/orcl/data03.dbf
channel ORA_DISK_1: starting piece 1 at 2020-04-12 14:47:51
channel ORA_DISK_1: finished piece 1 at 2020-04-12 14:47:52
piece handle=/home/oracle/rmanbak/data03.bak tag=TAG20200412T144751 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 2020-04-12 14:47:52

4、设置表空间data03为offline

SQL> alter tablespace data03 offline;

Tablespace altered.

5、用vim编辑data03.dbf文件，然后保存。

[oracle@wgx orcl]$ vim -b data03.dbf

6、设置表空间data03为online

SQL> alter tablespace data03 online;
Tablespace altered.

二、查看t_emp表的数据

提示出现坏的数据块，结果如下：

SQL> select count(*) from scott.t_emp;
select count(*) from scott.t_emp
                           *
ERROR at line 1:
ORA-01578: ORACLE data block corrupted (file # 7, block # 158)
ORA-01110: data file 7: '/usr/local/oradata/orcl/data03.dbf'

三、使用RMAN修复损坏的数据块

1、查看损坏的数据块的信息

可以看到，有两个数据块发生损坏。

SQL> select file#,block# from v$database_block_corruption;

     FILE#     BLOCK#
---------- ----------
	 7	  163
	 7	  158

Elapsed: 00:00:00.04

2、使用RMAN修复损坏的数据块

RMAN> blockrecover corruption list;

Starting recover at 2020-04-12 14:53:35
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=9 device type=DISK
allocated channel: ORA_DISK_2
channel ORA_DISK_2: SID=133 device type=DISK

channel ORA_DISK_1: restoring block(s)
channel ORA_DISK_1: specifying block(s) to restore from backup set
restoring blocks of datafile 00007
channel ORA_DISK_1: reading from backup piece /home/oracle/rmanbak/data03.bak
channel ORA_DISK_1: piece handle=/home/oracle/rmanbak/data03.bak tag=TAG20200412T144751
channel ORA_DISK_1: restored block(s) from backup piece 1
channel ORA_DISK_1: block restore complete, elapsed time: 00:00:01

starting media recovery
media recovery complete, elapsed time: 00:00:03

Finished recover at 2020-04-12 14:53:40

四、查看t_emp表的数据

SQL> select count(*) from scott.t_emp;

  COUNT(*)
----------
     19999

五、查看损坏的数据块的信息

SQL> select file#,block# from v$database_block_corruption;

no rows selected

修复成功！