Use RMAN to backup and restore the database (10)-repair damaged data blocks
If a data file is normal, but some data blocks in the data file are damaged, you can use RMAN to repair it.
1. Simulated data block damage
1. Create a new tablespace data03
Create a new table space data03 with a file size of 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$datafile;
NAME
-----------------------------------------------------------------------------------
/usr/local/oradata/orcl/system01.dbf
/usr/local/oradata/orcl/sysaux01.dbf
/usr/local/oradata/orcl/undotbs01.dbf
/usr/local/oradata/orcl/users01.dbf
/usr/local/oradata/orcl/data01.dbf
/usr/local/oradata/orcl/data02.dbf
/usr/local/oradata/orcl/data03.dbf
2. Create a table in the tablespace data03
Create a scott.t_emp table in the table space and add data to fill the entire table space.
SQL> create table scott.t_emp tablespace data03 as select * from scott.e02 where rownum<20000;
Table created.
3. Use RMAN to backup table space
RMAN> recover tablespace data03;
Starting recover at 2020-04-12 14:45:55
using channel ORA_DISK_1
using channel ORA_DISK_2
starting media recovery
media recovery complete, elapsed time: 00:00:00
Finished recover at 2020-04-12 14:45:56
RMAN> backup tablespace data03 format '/home/oracle/rmanbak/data03.bak';
Starting backup at 2020-04-12 14:47:50
using channel ORA_DISK_1
using channel ORA_DISK_2
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00007 name=/usr/local/oradata/orcl/data03.dbf
channel ORA_DISK_1: starting piece 1 at 2020-04-12 14:47:51
channel ORA_DISK_1: finished piece 1 at 2020-04-12 14:47:52
piece handle=/home/oracle/rmanbak/data03.bak tag=TAG20200412T144751 comment=NONE
channel ORA_DISK_1: backup set complete, elapsed time: 00:00:01
Finished backup at 2020-04-12 14:47:52
4. Set the tablespace data03 to offline
SQL> alter tablespace data03 offline;
Tablespace altered.
5. Edit the data03.dbf file with vim and save it.
[oracle@wgx orcl]$ vim -b data03.dbf
6. Set the tablespace data03 to online
SQL> alter tablespace data03 online;
Tablespace altered.
Two, view the data of the t_emp table
Prompt that there is a bad data block, the result is as follows:
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'
Three, use RMAN to repair damaged data blocks
1. View the information of the damaged data block
As you can see, two data blocks are damaged.
SQL> select file#,block# from v$database_block_corruption;
FILE# BLOCK#
---------- ----------
7 163
7 158
Elapsed: 00:00:00.04
2. Use RMAN to repair damaged data blocks
RMAN> blockrecover corruption list;
Starting recover at 2020-04-12 14:53:35
using target database control file instead of recovery catalog
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=9 device type=DISK
allocated channel: ORA_DISK_2
channel ORA_DISK_2: SID=133 device type=DISK
channel ORA_DISK_1: restoring block(s)
channel ORA_DISK_1: specifying block(s) to restore from backup set
restoring blocks of datafile 00007
channel ORA_DISK_1: reading from backup piece /home/oracle/rmanbak/data03.bak
channel ORA_DISK_1: piece handle=/home/oracle/rmanbak/data03.bak tag=TAG20200412T144751
channel ORA_DISK_1: restored block(s) from backup piece 1
channel ORA_DISK_1: block restore complete, elapsed time: 00:00:01
starting media recovery
media recovery complete, elapsed time: 00:00:03
Finished recover at 2020-04-12 14:53:40
Four, view the data of the t_emp table
SQL> select count(*) from scott.t_emp;
COUNT(*)
----------
19999
Five, view the information of the damaged data block
SQL> select file#,block# from v$database_block_corruption;
no rows selected