利用RMAN检测数据库坏块的脚本

2011/11/30 by admin 4 Comments

虽然我们也可以通过dbv(db file verify)工具做到对单个数据文件的坏块检测，但是直接使用RMAN的”backup validate check logical database;”结合V$DATABASE_BLOCK_CORRUPTION视图要方便地多。

如果自己搞不定可以找ASKMACLEAN专业ORACLE数据库修复团队成员帮您恢复!

Script:

1) $ rman target / nocatalog

2) RMAN> run {
allocate channel d1 type disk;
allocate channel d2 type disk;
allocate channel d3 type disk;
allocate channel d4 type disk;
backup validate check logical database;
}

3) select * from V$DATABASE_BLOCK_CORRUPTION ;

REM www.askmac.cn & www.askmac.cn

4) If V$DATABASE_BLOCK_CORRUPTION contains rows please run this query to 
find the objects that contains the corrupted blocks:

SELECT e.owner,
       e.segment_type,
       e.segment_name,
       e.partition_name,
       c.file#,
       greatest(e.block_id, c.block#) corr_start_block#,
       least(e.block_id + e.blocks - 1, c.block# + c.blocks - 1) corr_end_block#,
       least(e.block_id + e.blocks - 1, c.block# + c.blocks - 1) -
       greatest(e.block_id, c.block#) + 1 blocks_corrupted,
       null description
  FROM dba_extents e, v$database_block_corruption c
 WHERE e.file_id = c.file#
   AND e.block_id <= c.block# + c.blocks - 1
   AND e.block_id + e.blocks - 1 >= c.block#
UNION
SELECT s.owner,
       s.segment_type,
       s.segment_name,
       s.partition_name,
       c.file#,
       header_block corr_start_block#,
       header_block corr_end_block#,
       1 blocks_corrupted,
       'Segment Header' description
  FROM dba_segments s, v$database_block_corruption c
 WHERE s.header_file = c.file#
   AND s.header_block between c.block# and c.block# + c.blocks - 1
UNION
SELECT null owner,
       null segment_type,
       null segment_name,
       null partition_name,
       c.file#,
       greatest(f.block_id, c.block#) corr_start_block#,
       least(f.block_id + f.blocks - 1, c.block# + c.blocks - 1) corr_end_block#,
       least(f.block_id + f.blocks - 1, c.block# + c.blocks - 1) -
       greatest(f.block_id, c.block#) + 1 blocks_corrupted,
       'Free Block' description
  FROM dba_free_space f, v$database_block_corruption c
 WHERE f.file_id = c.file#
   AND f.block_id <= c.block# + c.blocks - 1
   AND f.block_id + f.blocks - 1 >= c.block#
 order by file#, corr_start_block#;

SELECT tablespace_name, segment_type, owner, segment_name
FROM dba_extents
WHERE file_id = &fileid
and &blockid between block_id AND block_id + blocks - 1;

Filed Under: Oracle, Oracle脚本script Tagged With: backup validate check, rman, V$DATABASE_BLOCK_CORRUPTION

Comments

maclean says

2011/12/01 at 18:25

有同学提出backup validate check logical database; 是否会对数据块做物理讹误检测或逻辑讹误检测的问题。实际上关于这一点官方文档有明确的说明, 见http://docs.oracle.com/cd/B28359_01/backup.111/b28270/rcmvalid.htm

Basic Concepts of RMAN Validation

The database prevents operations that result in unusable backup files or corrupted restored datafiles. The database automatically does the following:

Blocks access to datafiles while they are being restored or recovered

Permits only one restore operation for each datafile at a time

Ensures that incremental backups are applied in the correct order

Stores information in backup files to allow detection of corruption

Checks a block every time it is read or written in an attempt to report a corruption as soon as it has been detected

Checksums and Corrupt Blocks

A corrupt block is a block that has been changed so that it differs from what Oracle Database expects to find. Block corruptions can be caused by a number of different failures including, but not limited to the following:

Faulty disks and disk controllers

Faulty memory

Oracle Database software defects

DB_BLOCK_CHECKSUM is a database initialization parameter that controls the writing of checksums for the blocks in datafiles and online redo log files in the database (not backups). If DB_BLOCK_CHECKSUM is typical, then the database computes a checksum for each block during normal operations and stores it in the header of the block before writing it to disk. When the database reads the block from disk later, it recomputes the checksum and compares it to the stored value. If the values do not match, then the block is corrupt.

By default, the BACKUP command computes a checksum for each block and stores it in the backup. The BACKUP command ignores the values of DB_BLOCK_CHECKSUM because this initialization parameter applies to datafiles in the database, not backups.
Physical and Logical Block Corruption

In a physical corruption, which is also called a media corruption, the database does not recognize the block at all: the checksum is invalid, the block contains all zeros, or the header and footer of the block do not match.

Note:
By default, the BACKUP command computes a checksum for each block and stores it in the backup. If you specify the NOCHECKSUM option, then RMAN does not perform a checksum of the blocks when creating the backup.

In a logical corruption, the contents of the block are logically inconsistent. Examples of logical corruption include corruption of a row piece or index entry. If RMAN detects logical corruption, then it logs the block in the alert log and server session trace file.

By default, RMAN does not check for logical corruption. If you specify CHECK LOGICAL on the BACKUP command, however, then RMAN tests data and index blocks for logical corruption, such as corruption of a row piece or index entry, and log them in the alert log located in the Automatic Diagnostic Repository (ADR). If you use RMAN with the following configuration when backing up or restoring files, then it detects all types of block corruption that are possible to detect:

In the initialization parameter file of a database, set DB_BLOCK_CHECKSUM=typical so that the database calculates datafile checksums automatically (not for backups, but for datafiles in use by the database)

Do not precede the BACKUP or RESTORE command with SET MAXCORRUPT so that RMAN does not tolerate any block corruptions

In a BACKUP command, do not specify the NOCHECKSUM option so that RMAN calculates a checksum when writing backups

In BACKUP and RESTORE commands, specify the CHECK LOGICAL option so that RMAN checks for logical as well as physical corruption

回复
maclean says

2011/12/09 at 22:59

RMAN> run {
2> allocate channel d1 type disk;
3> allocate channel d2 type disk;
4> allocate channel d3 type disk;
5> allocate channel d4 type disk;
6> backup validate check logical database;
7> }

released channel: ORA_DISK_1
allocated channel: d1
channel d1: SID=14 instance=VPROD1 device type=DISK

allocated channel: d2
channel d2: SID=160 instance=VPROD1 device type=DISK

allocated channel: d3
channel d3: SID=159 instance=VPROD1 device type=DISK

allocated channel: d4
channel d4: SID=29 instance=VPROD1 device type=DISK

Starting backup at 10-DEC-11
channel d1: starting full datafile backup set
channel d1: specifying datafile(s) in backup set
input datafile file number=00001 name=+DATA/vprod/datafile/system.490.769483911
input datafile file number=00007 name=+DATA/vprod/datafile/undo11.483.769484067
channel d2: starting full datafile backup set
channel d2: specifying datafile(s) in backup set
input datafile file number=00006 name=+DATA/vprod/datafile/undotbs2.487.769483991
input datafile file number=00005 name=+DATA/vprod/datafile/example.486.769484027
channel d3: starting full datafile backup set
channel d3: specifying datafile(s) in backup set
input datafile file number=00002 name=+DATA/vprod/datafile/sysaux.489.769483855
channel d4: starting full datafile backup set
channel d4: specifying datafile(s) in backup set
input datafile file number=00004 name=+DATA/vprod/datafile/users.488.769483967
input datafile file number=00003 name=+DATA/vprod/datafile/undo22.485.769484051
channel d2: backup set complete, elapsed time: 00:02:46
List of Datafiles
=================
File Status Marked Corrupt Empty Blocks Blocks Examined High SCN
—- —— ————– ———— ————— ———-
5 OK 0 33656 44242 8912531
File Name: +DATA/vprod/datafile/example.486.769484027
Block Type Blocks Failing Blocks Processed
———- ————– —————-
Data 0 6595
Index 0 1148
Other 0 2841

File Status Marked Corrupt Empty Blocks Blocks Examined High SCN
—- —— ————– ———— ————— ———-
6 OK 0 1 67200 9674203
File Name: +DATA/vprod/datafile/undotbs2.487.769483991
Block Type Blocks Failing Blocks Processed
———- ————– —————-
Data 0 0
Index 0 0
Other 0 67199

channel d2: starting full datafile backup set
channel d2: specifying datafile(s) in backup set
including current control file in backup set
channel d3: backup set complete, elapsed time: 00:02:51
List of Datafiles
=================
File Status Marked Corrupt Empty Blocks Blocks Examined High SCN
—- —— ————– ———— ————— ———-
2 OK 0 25919 111362 9850434
File Name: +DATA/vprod/datafile/sysaux.489.769483855
Block Type Blocks Failing Blocks Processed
———- ————– —————-
Data 0 28527
Index 0 24857
Other 0 32057

channel d3: starting full datafile backup set
channel d3: specifying datafile(s) in backup set
including current SPFILE in backup set
channel d2: backup set complete, elapsed time: 00:00:04
List of Control File and SPFILE
===============================
File Type Status Blocks Failing Blocks Examined
———— —— ————– —————
Control File OK 0 1136
channel d3: backup set complete, elapsed time: 00:00:00
List of Control File and SPFILE
===============================
File Type Status Blocks Failing Blocks Examined
———— —— ————– —————
SPFILE OK 0 2
channel d1: backup set complete, elapsed time: 00:03:02
List of Datafiles
=================
File Status Marked Corrupt Empty Blocks Blocks Examined High SCN
—- —— ————– ———— ————— ———-
1 OK 0 14338 93480 9850357
File Name: +DATA/vprod/datafile/system.490.769483911
Block Type Blocks Failing Blocks Processed
———- ————– —————-
Data 0 62319
Index 0 13177
Other 0 3606

File Status Marked Corrupt Empty Blocks Blocks Examined High SCN
—- —— ————– ———— ————— ———-
7 OK 0 37758 38400 9849139
File Name: +DATA/vprod/datafile/undo11.483.769484067
Block Type Blocks Failing Blocks Processed
———- ————– —————-
Data 0 0
Index 0 0
Other 0 642

channel d4: backup set complete, elapsed time: 00:03:10
List of Datafiles
=================
File Status Marked Corrupt Empty Blocks Blocks Examined High SCN
—- —— ————– ———— ————— ———-
3 OK 0 38249 38400 9850434
File Name: +DATA/vprod/datafile/undo22.485.769484051
Block Type Blocks Failing Blocks Processed
———- ————– —————-
Data 0 0
Index 0 0
Other 0 151

File Status Marked Corrupt Empty Blocks Blocks Examined High SCN
—- —— ————– ———— ————— ———-
4 OK 0 6388 71873 9849137
File Name: +DATA/vprod/datafile/users.488.769483967
Block Type Blocks Failing Blocks Processed
———- ————– —————-
Data 0 50510
Index 0 13091
Other 0 1851

Finished backup at 10-DEC-11
released channel: d1
released channel: d2
released channel: d3
released channel: d4

回复
chengwill says

2012/02/07 at 09:35

Hello

I have trial the script and got the right result.

So I think this is an excellent effective measure!

BTW:Thanks the Maclean provide it to us!

There are some backup logs from the oracle 11GR1 RAC test-bed environment:

RMAN> backup validate check logical database;
Starting backup at 06-FEB-12
allocated channel: ORA_DISK_1
channel ORA_DISK_1: SID=1326 instance=ssp1 device type=DISK
allocated channel: ORA_DISK_2
channel ORA_DISK_2: SID=1300 instance=ssp2 device type=DISK
file 13 is excluded from whole database backup
file 14 is excluded from whole database backup
file 15 is excluded from whole database backup
file 16 is excluded from whole database backup
file 17 is excluded from whole database backup
file 19 is excluded from whole database backup
channel ORA_DISK_1: starting full datafile backup set
channel ORA_DISK_1: specifying datafile(s) in backup set
input datafile file number=00020 name=/dev/raw/raw36
input datafile file number=00022 name=/dev/raw/raw38
…
input datafile file number=00037 name=/dev/raw/raw45
input datafile file number=00044 name=/dev/raw/raw19
input datafile file number=00010 name=/dev/raw/raw26
input datafile file number=00012 name=/dev/raw/raw28
channel ORA_DISK_2: starting full datafile backup set
channel ORA_DISK_2: specifying datafile(s) in backup set
input datafile file number=00018 name=/dev/raw/raw34
input datafile file number=00021 name=/dev/raw/raw37
…
input datafile file number=00011 name=/dev/raw/raw27
channel ORA_DISK_1: backup set complete, elapsed time: 00:33:56
List of Datafiles
=================
File Status Marked Corrupt Empty Blocks Blocks Examined High SCN
—- —— ————– ———— ————— ———-
3 OK 0 1 256000 285534307
File Name: /dev/raw/raw18
Block Type Blocks Failing Blocks Processed
———- ————– —————-
Data 0 0
Index 0 0
Other 0 255999

…

File Status Marked Corrupt Empty Blocks Blocks Examined High SCN
—- —— ————– ———— ————— ———-
43 OK 0 255276 256000 285347887
File Name: /dev/raw/raw7
Block Type Blocks Failing Blocks Processed
———- ————– —————-
Data 0 466
Index 0 70
Other 0 188

Finished backup at 06-FEB-12

回复
- Maclean Liu says
  
  2012/02/08 at 00:23
  
  Thx for your comment here !
  
  回复

利用RMAN检测数据库坏块的脚本

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