Re: corrupted block

An export is a great method for catching corruptions in tables. However, it does not read indexes, so it misses those corruptions. Analyze and dbv will.

Yechiel Adar wrote:

>We had a session with an expert on Monday and he recommended export to
>\dev\nul to detect errors in the database.
>
>Yechiel Adar
>Mehish
>----- Original Message -----
>To: Multiple recipients of list ORACLE-L <ORACLE-L_at_fatcity.com>
>Sent: Monday, February 24, 2003 10:41 PM
>
>
>
>
>>I had the same belief that RMAN catches the corruption earlier, but not
>>
>>
>NOW.
>
>
>>We had a database crash two months back and while performing the
>>recovery(RMAN) one of the restored data file was corrupted. *BIG SHOCK*
>>
>>
>to
>
>
>>everyone..We ran the dbverify on the restored files, the corruption showed
>>up easily.. But not a single clue on the RMAN backup logs'.
>>
>>We asked Oracle Support, if rman checks for corruption in the data files
>>when the data files are being backed up.. He said "No"..
>>
>>Oracle Ver: 8.1.7.2/Sun 2.6
>>
>>
>>..Ponnusamy
>>
>>At 11:40 AM 2/24/2003 -0800, DENNIS WILLIAMS wrote:
>>
>>
>>>Stephen
>>> RMAN ignored your corrupted block? Ya gotta tell us more man! We're
>>>relying on it to catch everything. Did you have the MAXCORRUPT parameter
>>>set?
>>>
>>>Dennis Williams
>>>DBA, 40%OCP, 100% DBA
>>>Lifetouch, Inc.
>>>dwilliams_at_lifetouch.com
>>>
>>>
>>>-----Original Message-----
>>>Sent: Monday, February 24, 2003 11:45 AM
>>>To: Multiple recipients of list ORACLE-L
>>>
>>>
>>>
>>>I think more recent versions of Oracle have options for skipping corrupt
>>>blocks with exports.
>>>
>>>One possible way:
>>>If you have a valid primary key index on the table, and the index is in a
>>>good tablespace, you might be able to cycle through all the primary keys,
>>>select the row corresponding to that primary key and insert it into a new
>>>table. I was able to do this about a month ago with a 8.1.7 database.
>>>
>>>
>In
>
>
>>>my case, I think it was a block header that was corrupt, not data; so I
>>>
>>>
>got
>
>
>>>all the data OK. It was rather slow, grabbing and inserting one row at a
>>>time; but I got all the data. As long as I didn't do anything that would
>>>cause a table scan of any kind, I could get the data.
>>>
>>>By the way, rman not only failed to spot the corruption, but backed it up
>>>AND restored the corruption! My initial attempt was to just rename the
>>>datafile at the file system level, then recover it from the previous
>>>
>>>
>backup.
>
>
>>>I could relate another one of those TAR non-support -- total and complete
>>>NON-support! -- on this one.
>>>
>>>
>>>
>>>>-----Original Message-----
>>>>
>>>>So my question is, if all backups contain the corrupted
>>>>block, how would
>>>>I copy all non-corrupted blocks from this table into a new table?
>>>>
>>>>
>>>>
>>>--
>>>Please see the official ORACLE-L FAQ: http://www.orafaq.net
>>>--
>>>Author: Stephen Lee
>>> INET: Stephen.Lee_at_DTAG.Com
>>>
>>>Fat City Network Services -- 858-538-5051 http://www.fatcity.com
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>>>--
>>>Author: DENNIS WILLIAMS
>>> INET: DWILLIAMS_at_LIFETOUCH.COM
>>>
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>>--
>>Please see the official ORACLE-L FAQ: http://www.orafaq.net
>>--
>>Author: Ponnusamy
>> INET: t_pranga_at_qualcomm.com
>>
>>Fat City Network Services -- 858-538-5051 http://www.fatcity.com
>>San Diego, California -- Mailing list and web hosting services
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>>
>>
>
>
>

-- 
Please see the official ORACLE-L FAQ: http://www.orafaq.net
-- 
Author: Daniel W. Fink
  INET: optimaldba_at_yahoo.com

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