Re: Block Corruption in empty pages in Oracle 11g

From: Mark D Powell <Mark.Powell2_at_hp.com>
Date: Thu, 5 Aug 2010 05:18:35 -0700 (PDT)
Message-ID: <fb8518e4-b175-4d6c-bbd8-6b74692b7756_at_14g2000yqa.googlegroups.com>

On Aug 4, 11:08 pm, zigzagdna <zigzag..._at_yahoo.com> wrote:
> I am using Oracle 11.1.0.7.1 on HP UNIX 11i.
> On several occasions, I have been seen that block corruptions are
> reported by rman. I have never seen this problem in previous release
> of databases; but I have seen it more than once in Oracle 11g.
> However, when I run dbv command; I do not see any corruption in data
> and index blocks; so my conclusion is block corruption is in empty
> pages.
> Anyone has ideas why block corruption occurs in Oracle 11g. Has
> Oracle’s algorithm for checking block corruption have changed in 11g;
> I.e.; these corruptions existed in older Oracle releases but not
> reported by rman,
>
> Another strange thing I noticed:
> 1. When doing export backup, export backup reports about corrupted
> blocks.
> 2. When I do expdp no errors are reported.
> So question is why is exp command checking empty blocks?
>
> Any insights in above will be appreciated.

If the rman backup and expdp are identifying corrupted blocks what does the following query show?

set echo off

--
-- Display corrupt block information
--
-- 20100105  Mark D Powell   Save 4 future use
--
select
  *
from
  v$database_block_corruption
order by
  file#
 ,block#
/

You can find the object idenfified by this query by looking at
dba_extents for the extent that the identified files and blocks are
held within.

HTH -- Mark D Powell --

Received on Thu Aug 05 2010 - 07:18:35 CDT