Re: Urgent: System tablespace corruption

First of all, I have seen several times in this group people stating dbv can provide unpredictable results, and it is not reliable, at least not in 7.3. This might be false alarm.
Secondly, I would assume you normally would have db_block_checksum = false, unless you suspect some sort of hardware problem. Setting this parameter to true is done only in exceptional situations. Thirdly, you could easily find the corrupted segment using the dba_extents view

select segment_name, segment_type
from dba_extents e, dba_data_files f
where e.file_id = f.file_id
and 100 >= block_id and 100 <= block_id + e.blocks and f.file_name = 'C:\ORACLE\ORADATA\ORCL\SYSTEM01.DBF'

where 100 is the number of the affected block and the filename is the name of the affected file.

Depending on where the corruption is, exp looks the only way to go, at least if those blocks are truly corrupt.
However, of course the datadictionary is used to determine which objects to export.
I would recommend posting the outcome of the above query here.

Hope this of some help.
Good luck,

Sybrand Bakker, Oracle DBA

"Amol" <addprabha_at_my-deja.com> wrote in message news:8qk8rg$rgb$1_at_nnrp1.deja.com...
> Oracle gurus,
>
> I have oracle 7.3.4 and the problem I am facing is block corruption in
> system tablespace. I cannot restore it from any of the backups as the
> corruption exists in all the backups of the DB. I did verify this using
> the tool "dbv". Please suggest if in any way the corruption can be
> removed without loss of any data.
>
> Can I use the export utility for the above problem? What would be the
> implication if I change the parameter DB_BLOCK_CHECKSUM to false? Will
> it solve this problem? Also suggest how to find which table/index is
> corrupt from the system datafile. This is very urgent and your
> suggestions will be very much appreciated.
>
> Amol
>
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
Received on Sun Sep 24 2000 - 04:02:50 CDT