RE: v$database_block_corruption not cleared

So if it is inconvenient to get rid of that file any time soon you will want to create dummy tables until one takes that block. Small tables created in a “do another?” loop and checking for the bad blocks to have been used in another connection.  

Then you can drop all the dummies except the one(s) with the bad block(s).  

Rename the dummies with bad blocks something like BadBlock_ff_ssssss_eeeeee  

where ff is the file number, ssssss is the start block, and eeeee is the end block.  

Suggest that the table creator/owner be a dba_only_maint account, but not system or sys.  

Then clear out the files and drop the tablespace when convenient or leave the bad blocks pinned by the carefully chosen table name to never drop or move forever.  

When you could arbitrarily allocate extents this was easier, but we lost that in the enhancements to uniform and system geometric sizes.  

Good luck.  

mwf  

From: oracle-l-bounce_at_freelists.org [mailto:oracle-l-bounce_at_freelists.org] On Behalf Of nilesh kumar Sent: Tuesday, January 04, 2022 11:17 PM To: nenad.noveljic_at_vontobel.com
Cc: Leng; ORACLE-L
Subject: Re: v$database_block_corruption not cleared  

Hello Nenad,  

I had faced a similar issue on the Windows platform, the corrupted block was not getting cleared.

When the Platform team reorg the disk, it got removed permanently.  

Thanks

Nilesh  

On Fri, Dec 10, 2021 at 4:52 PM Noveljic Nenad <nenad.noveljic_at_vontobel.com> wrote:

Hi Leng,  

Thank you for the article.  

The block was returned to the free list:  

set lines 200 pages 10000

col segment_name format a30  

SELECT e.owner, e.segment_type, e.segment_name, e.partition_name, c.file#

, greatest(e.block_id, c.block#) corr_start_block#

, least(e.block_id+e.blocks-1, c.block#+c.blocks-1) corr_end_block#

, least(e.block_id+e.blocks-1, c.block#+c.blocks-1)

• greatest(e.block_id, c.block#) + 1 blocks_corrupted

, null description

FROM dba_extents e, v$database_block_corruption c

WHERE e.file_id = c.file#

AND e.block_id <= c.block# + c.blocks - 1

AND e.block_id + e.blocks - 1 >= c.block#

UNION SELECT s.owner, s.segment_type, s.segment_name, s.partition_name, c.file#

, header_block corr_start_block#

, header_block corr_end_block#

, 1 blocks_corrupted

, 'Segment Header' description

FROM dba_segments s, v$database_block_corruption c

WHERE s.header_file = c.file#

AND s.header_block between c.block# and c.block# + c.blocks - 1

UNION SELECT null owner, null segment_type, null segment_name, null partition_name, c.file#

, greatest(f.block_id, c.block#) corr_start_block#

, least(f.block_id+f.blocks-1, c.block#+c.blocks-1) corr_end_block#

, least(f.block_id+f.blocks-1, c.block#+c.blocks-1)

• greatest(f.block_id, c.block#) + 1 blocks_corrupted

, 'Free Block' description

FROM dba_free_space f, v$database_block_corruption c

WHERE f.file_id = c.file#

AND f.block_id <= c.block# + c.blocks - 1

AND f.block_id + f.blocks - 1 >= c.block#

ORDER BY file#, corr_start_block#;  

OWNER                                                                                                                            SEGMENT_TYPE       SEGMENT_NAME

-------------------------------------------------------------------------------------------------------------------------------- ------------------ ------------------------------

PARTITION_NAME                                                                                                                        FILE# CORR_START_BLOCK# CORR_END_BLOCK# BLOCKS_CORRUPTED

-------------------------------------------------------------------------------------------------------------------------------- ---------- ----------------- --------------- ----------------

DESCRIPTION

                                                                                                                                          7            694199          694199                1

Free Block    

                                                                                                                                          8            174445          174445                1

Free Block  

Best regards,  

Nenad  

From: Leng <lkaing_at_gmail.com>
Sent: Freitag, 10. Dezember 2021 11:24
To: Noveljic Nenad <nenad.noveljic_at_vontobel.com> Cc: ORACLE-L <oracle-l_at_freelists.org> Subject: Re: v$database_block_corruption not cleared  

• E-Mail from outside Vontobel: Do not click on links or open attachments unless you know the content is safe. ***

Hi Nenad,  

The corrupted block is returned to the free list to be reused. When a block is reused it is reformatted and that’s when the corruption is finally cleared.  

If you want to format it right away then you’ll need to try and create an object in the particular datafile and hope it picks up the corrupted block.  

See 336133.1  

Cheers,

Leng    

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Thanks & Regards
Nilesh
Oracle DBA (sqlplus "/as sysdba" is my world)

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