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RMAN Block Recovery | Oracle DBA – Tips and Techniques
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RMAN Block Recovery

  • Posted by Gavin Soorma
  • On June 28, 2009
  • 0 Comments
From Oracle 9i onwards you can use RMAN to recover only blocks while database is up and
running.

This could possibly save hours and hours of recovery time as a full database restore
 is not necessary.

Error reported by user pointing to block corruption.

 POPULATE_MACSDATA - ORA-01578: ORACLE data block corrupted
(file # 48, block # 142713)
ORA-01110: data file 48: '/hqlinux08db06/ORACLE/macsl/MACSDAT_2006_06.dbf'
ORA-02063: preceding 2 lines from MODSL_MACSL_LINK
File name : /hqlinux08db06/ORACLE/macsl/MACSDAT_2006_06.dbf

Check first if the there is only one(few) blocks corrupted or most of the blocks are
corrupted.

macsl:/opt/oracle/admin/macsl/bdump>

Issue command below at UNIX prompt.

dbv file=/hqlinux08db06/ORACLE/macsl/MACSDAT_2006_06.dbf BLOCKSIZE=8192
LOGFILE=test.log

DBVERIFY: Release 10.2.0.1.0 - Production on Wed Oct 4 14:28:37 2006
Copyright (c) 1982, 2005, Oracle.  All rights reserved.
DBV-00200: Block, dba 201469305, already marked corrupted

macsl:/opt/oracle/admin/macsl/bdump> vi test.log
DBVERIFY: Release 10.2.0.1.0 - Production on Wed Oct 4 14:28:37 2006
Copyright (c) 1982, 2005, Oracle.  All rights reserved.
DBVERIFY - Verification starting : FILE = /hqlinux08db06/ORACLE/macsl/MACSDAT_2006_06.dbf
DBVERIFY - Verification complete
Total Pages Examined         : 262144
Total Pages Processed (Data) : 218615
Total Pages Failing   (Data) : 0
Total Pages Processed (Index): 0
Total Pages Failing   (Index): 0
Total Pages Processed (Other): 22422
Total Pages Processed (Seg)  : 0
Total Pages Failing   (Seg)  : 0
Total Pages Empty            : 21107
Total Pages Marked Corrupt   : 1
Total Pages Influx           : 0
Highest block SCN            : 2550111754 (1040.2550111754)

You can get the list of corrupted blocks from  v$database_block_corruption

SQL> Select * from v$database_block_corruption;

You will get block number corrupt.
Ex: block 142713.

After that LOGIN TO RMAN.

macsl:/opt/oracle/admin/macsl/bdump> rman target / catalog rman10/rman10@rman10p
Recovery Manager: Release 10.2.0.1.0 - Production on Wed Oct 4 14:33:26 2006
Copyright (c) 1982, 2005, Oracle.  All rights reserved.
connected to target database: MACSL (DBID=1125502194)
connected to recovery catalog database

RMAN> BLOCKRECOVER DATAFILE 48 BLOCK 142713;;

Starting blockrecover at 04-OCT-06
allocated channel: ORA_SBT_TAPE_1
channel ORA_SBT_TAPE_1: sid=119 devtype=SBT_TAPE
channel ORA_SBT_TAPE_1: Tivoli Data Protection for Oracle: version 5.2.0.0
allocated channel: ORA_DISK_1
channel ORA_DISK_1: sid=131 devtype=DISK

channel ORA_SBT_TAPE_1: restoring block(s)
channel ORA_SBT_TAPE_1: specifying block(s) to restore from backup set
restoring blocks of datafile 00048
channel ORA_SBT_TAPE_1: reading from backup piece MACSL.20061004.7379.1.1.602899473
channel ORA_SBT_TAPE_1: restored block(s) from backup piece 1
piece handle=MACSL.20061004.7379.1.1.602899473 tag=TAG20061003T222108
channel ORA_SBT_TAPE_1: reading from backup piece MACSL.20061004.7379.2.1.602899473
channel ORA_SBT_TAPE_1: restored block(s) from backup piece 2
piece handle=MACSL.20061004.7379.2.1.602899473 tag=TAG20061003T222108
channel ORA_SBT_TAPE_1: block restore complete, elapsed time: 00:04:01

starting media recovery
media recovery complete, elapsed time: 00:00:46

Finished blockrecover at 04-OCT-06

Additional information:

V$database_block_corruption is the view to check the list of corrupted blocks.

If you have multiple block list as corrupt, You can use single command to recover them.

RMAN> BLOCKRECOVER corruption list;
 

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