Oracle database internals by Riyaj

Discussions about Oracle performance tuning, RAC, Oracle internal & E-business suite.

Posts Tagged ‘corruption’

How to reformat corrupt blocks which are not part of any segment?

Posted by Riyaj Shamsudeen on July 11, 2014

There was a question in . Problem is that there were many corrupt blocks in the system tablespace not belonging to any segment. Both DBV and rman throws errors, backup is filling the v$database_block_corruption with numerous rows. OP asked to see if these blocks can be reinitialized. Also, note 336133.1 is relevant to this issue on hand.

$ dbv file=/oracle/SID/system_1/system.data1

DBVERIFY: Release 10.2.0.5.0 - Production on Fri Jul 11 08:04:18 2014

Copyright (c) 1982, 2007, Oracle.  All rights reserved.

DBVERIFY - Verification starting : FILE = /oracle/SID/system_1/system.data1
Block Checking: DBA = 67121421, Block Type = Save undo data block
ERROR: SAVE Undo Block Corrupted.  Error Code = 50
kts4subck: record (3) seq# (0), split flag (0)
and total pieces(0)
…
REM Many such corruptions.
select * from v$database_block_corruption order by 1,2,3,4  ;

FILE# BLOCK# BLOCKS CORRUPTION_CHANGE# CORRUPTIO
----- ------ ------ ------------------ ---------
    1  12557      1                  1 UNKNOWN
    1  12561      1                  1 UNKNOWN
    1  12589      1                  1 UNKNOWN
    1  12593      1                  1 UNKNOWN
..

From the output above, blocks belonging to saved undo data blocks, which probably have undo records referring to other data files also. Since these blocks do not belong to any segment (note 336133.1 has a SQL statement to verify that), we should be able to force the allocation of these blocks to a table, load that table with numerous rows, which, in theory, should re-initialize the blocks. That should eliminate rman and dbv errors.

First, let me take a selfie
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Posted in corruption, Oracle database internals, recovery | Tagged: , | 1 Comment »

 
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