How to Detect and Fix a Corruption in the Datafile OS Header/Block Zero - ORA-27047 DBV-107 ORA-1157/ORA-27048
(Doc ID 360032.1)
Last updated on JANUARY 31, 2022
Applies to:
Oracle Database - Enterprise Edition - Version 8.0.5.0 to 12.1.0.2 [Release 8.0.5 to 12.1]Oracle Database Cloud Schema Service - Version N/A and later
Oracle Database Exadata Cloud Machine - Version N/A and later
Oracle Cloud Infrastructure - Database Service - Version N/A and later
Oracle Database Cloud Exadata Service - Version N/A and later
Information in this document applies to any platform.
Symptoms
OS block in an Oracle file
- The OS Block Header is in the first datafile block. It is used by Oracle to store Operating System information.
- It is the Block Zero. It is not the datafile header which is in Oracle Block 1.
- Corruption in Block Zero will not cause damage to the data and in versions lower than 11g it is not detected by dbverify/rman. In 11g Dbverify has been enhanced to detect it.
- dbfsize can be used to check the consistency of Block 0.
- When this block is corrupted the database may sometimes be opened with no errors as Block 0 is only checked by some specific database operations like 'CREATE CONTROLFILE' or in 11g during Database OPEN.
Symptoms
- Creating the control file may report error ORA-27047 when OS block header is invalid for a particular datafile:
ORA-27047 : unable to read the header block of file.
Example taken from HPUX:
Changes
Cause
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In this Document
Symptoms
OS block in an Oracle file
Symptoms
Changes
Cause
Solution
References
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