"Translated from MoS article" How to Detect and resolve DataFile OS header (Block Zero) Damage--ORA-27047 DBV-107 ora-1157/ora-27048

How to detect and resolve damage to the DataFile OS header (Block Zero)-ORA-27047 DBV-107 ora-1157/ora-27048

From:
How to Detect and Fix a corruption in the datafile OS header/block zero-ora-27047 DBV-107 ora-1157/ora-27048 (document ID 3600 32.1)

Suitable for:
Oracle database-enterprise edition-version 8.0.5.0 to 12.1.0.2 [Release 8.0.5 to 12.1]
Information in this document applies to any platform.
Checked for relevance on 02-feb-15***

Symptoms:

OS block knowledge in Oracle file: The 1.THE OS block Header is the first block in DataFile and is used by Oracle to store operating system information. 2. Its block number is 0 (it's The Block Zero), and the DataFile header's block number is 1, and the two headers are not the same thing. 3.Block Zero damage does not result in data corruption and Block zero damage cannot be detected by DBV or Rman until Oracle 11g.   in the 11g DBV has been improved (enhanced), 11g of DBV can detect the damage of block zero. 4.dbfsize can be used to detect the consistency of block zero.  Note: For an example of dbfsize, see my article: http://blog.csdn.net/msdnchina/article/details/43345445 5. When block zero is damaged, sometimes The database may be open and there is no error (no errors).   Block Zero is checked under the following circumstances (checked):    5.1 Certain database operations, such as ' CREATE Controlfile '     5.2 in the 11g version, in the database is open process.

Symptoms:
1. When the OS block header is invalid, the creation of a control file may be reported on a particular datafile ORA-27047

  Ora-27047:unable to read the header block of file.

Here is an example of HPUX:

  Ora-1503:create Controlfile failed   ora-1565:error in identifying file '/oradata/users.dbf '   ora-27047:unable To read the header block of file   HP-UX error:22:invalid argument   Additional Information:2

2. The DBV utility, which is below the 11g version, will not report the error "Dbv-00107:unknown header format" DBV the corruption,11g on the data file.

3.database Upgrade (open migrate) or normal open may fail, reported error: ORA-01157 ORA-27048

Reason:
The OS Block header (block 0) in DataFile is corrupted

1. Corruption can be identified by Oracle utility Dbfsize

   $ dbfsize/oradata/users.dbf   Header block magic number is bad

Other errors identified by Dbfsize are:

   /oradata/users.dbf:header block file size is bad; Trying RAW file Format ...   /oradata/users.dbf:header Block magic number is bad   

2. Invalid datafile copy causes the problem. An example is when using the OS command DD to perform a file copying on a bare device and a filesystem. Reference Bug 4307836 (closed as not a bug) in HPUX.

3. File system corruption may cause this issue.

4.NetBackup may cause this problem, see note:373595.1

5.Bug 4721022/bug 4724358 may also cause it. See Note 4724358.8

Solution:
Use good control files to copy open database and resize datafile
1.resizing DataFile will reformat OS block header

  ALTER DATABASE datafile '/ORADATA/USERS.DBF ' resize <new size>;

Run dbfsize to confirm that the block has been repaired:

  $ dbfsize/oradata/users.dbf  Database file:/oradata/users.dbf  database file type:file system  Database File size:51200 8192 byte blocks

Note: Resize original size, reconstruction or error, need to resize a different size. --According to Source: http://www.cnblogs.com/rootq/archive/2012/12/12/2814579.html

2. If the problem is caused by file system corruption, running fsck on that file system may fix the problem.

3. Another way to solve this problem is to restore recover affected file from backup

References
Note:4724358.8-bug 4724358-ora-27045 ORA-1578 ORA-27047 corruption caused by dbms_ldap

Bug:4721022-ora-27045 reported intermittently and with BLOCK corruptions
Bug:4724358-using Dbms_ldap with CONNECTION POOLING CAN cause corruption/ora-27045
note:373595.1-ora-1578 ORA-27047 ORA-27048 corrupt blocks when using rman/netbackup

"Translated from MoS article" How to Detect and resolve DataFile OS header (Block Zero) Damage--ORA-27047 DBV-107 ora-1157/ora-27048