Block Corruption in Datafile

You can find such an entry in Alertlog as below.

Corrupt block relative dba: 0x08c00e60 (file 42, block 4258)
Bad header found during backing up datafile
Data in bad block -
type: 6 format: 2 rdba: 0x09000e60
last change scn: 0x058c.c60f01b6 seq: 0x1 flg: 0x02
consistency value in tail: 0x01b60601
check value in block header: 0x0, block checksum disabled
spare1: 0x0, spare2: 0x0, spare3: 0x0

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Reread of blocknum=4258, file=/disk1/db123_data/oradata/db123/dbfiles/TblSp6_data1.dbf. found same corrupt data
Mon Dec 15 23:26:59 2008

After this I found corrupted block and segment name which is following

SQL> SELECT tablespace_name, segment_type, owner, segment_name FROM dba_extents WHERE file_id = 42 and 4258 between block_id AND block_id + blocks - 1;

TABLESPACE_NAME SEGMENT_TYPE OWNER SEGMENT_NAME
-------------------------- -------------------- ------------ ----------------------
TBLSP6_DATA1 TABLE USER3 ALL_PAGES

SQL> select count(*) from USER3.ALL_PAGES;

select count(*) from USER3.ALL_PAGES
*
ERROR at line 1:
ORA-01578: ORACLE data block corrupted (file # 42, block # 4258)
ORA-01110: data file 42:
'/disk1/db123_data/oradata/db123/dbfiles/TBLSP6_DATA1.dbf'

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Solutin :

Offline the datafile move the existing datafile to other name and copy the old good datafile from backup and recover the datafile.