Re: Block Corruption in empty pages in Oracle 11g
Date: Sat, 14 Aug 2010 10:37:46 -0700 (PDT)
Message-ID: <67a91852-c024-479a-9c41-b95f27de69d3_at_p7g2000yqa.googlegroups.com>
On Aug 14, 12:32 am, zigzagdna <zigzag..._at_yahoo.com> wrote:
> On Aug 7, 1:39 pm, zigzagdna <zigzag..._at_yahoo.com> wrote:
>
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>
>
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> > On Aug 7, 5:54 am, John Hurley <hurleyjo..._at_yahoo.com> wrote:
>
> > > Mladen:
>
> > > > The command is:
>
> > > > ALTER SYSTEM DUMP DATAFILE <file_id> BLOCK MIN <min block>
> > > > BLOCK MAX <max block>;
>
> > > > On a real OS, one can have rather satisfactory results by doing:
>
> > > > dd if=<data file> bs=8k count=<count>|od -x
>
> > > > If the block size is not 8k, the corresponding value needs to be
> > > > substituted into the dd command.
>
> > > Some people actually take the time to ( on a test system ) introduce
> > > damage and test out their ability to find problems and recover from
> > > them. Shocking eh?
>
> > > Of course a hex editor can let you introduce just little tiny bits of
> > > corruption ... especially with tools that show one the structure of
> > > the blocks.
>
> > Thanks to all for provding your input; very useful. I do know how to
> > corrupt a blok using dd command. In fact, several years ago when I
> > took training on Oracle 9i or 10g; one of the classroom exercises was
> > to corrupt a block and recover it using rman block recover command. I
> > tried it on my database and I it seems to take same amount of time as
> > full recover; because it scans entire backup to serach for the blocks
> > specfied in the block recver command.
>
> > I am still at loss why this block corruption is happening; I have seen
> > it twtice on this system. It is hard to convince UNIX Administartors
> > that something is wrong in disk or disk controller; I even don't know
> > how they will find that. All they can do is to replace disks and disk
> > controllers.- Hide quoted text -
>
> > - Show quoted text -
>
> Can some one explain following ooutput from dbv; what is difference in
> total pages failing and corrupt pages. I see
> total pages marked corrupt as 1345; yet I do not see any data or index
> pages marked corrupt; and there is only 1 empty page. So where are
> those 1345 corrupt pages.
>
> DBVERIFY - Verification complete
>
> Total Pages Examined : 371200
> Total Pages Processed (Data) : 328622
> Total Pages Failing (Data) : 0
> Total Pages Processed (Index): 38
> Total Pages Failing (Index): 0
> Total Pages Processed (Other): 41194
> Total Pages Processed (Seg) : 0
> Total Pages Failing (Seg) : 0
> Total Pages Empty : 1
> Total Pages Marked Corrupt : 1345
> Total Pages Influx : 0
> Total Pages Encrypted : 0
> Highest block SCN : 3430163491 (2476.3430163491)
>
> DBVERIFY: Release 11.1.0.7.0 - Production on Sat Aug 14 00:25:24 2010- Hide quoted text -
>
> - Show quoted text -
My problem is even though pages shown as corrupted are not in data or
index blocks; statements such as
truncate table; delete from table... fail saying so dbv output is not
really correct? Also I do not know how to overcome such errors; ie.,
what is the woraround if I want to delete some rows from the table:
SQL> truncate table cat_fmly_corrupt;
truncate table cat_fmly_corrupt
*
ERROR at line 1:
ORA-01578: ORACLE data block corrupted (file # 5, block # 3457)
ORA-01110: data file 5: '/pqmsqa/oradb2/oradata/pqmsq/
s_pqms_01_d1.dbf'
SQL> delete from cat_fmly_corrupt;
delete from cat_fmly_corrupt
*
ERROR at line 1:
ORA-01578: ORACLE data block corrupted (file # 5, block # 4290)
ORA-01110: data file 5: '/pqmsqa/oradb2/oradata/pqmsq/
s_pqms_01_d1.dbf'
Received on Sat Aug 14 2010 - 12:37:46 CDT