Dropping Control Files steps - Oracle Control Files

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• Nirja Shah   -Posted on 28 Aug 15
  - A control file is a small binary file that records the physical structure of the database.
  - It includes:
  1. The database name
  2. Names and locations of associated datafiles and redo log files
  3. The timestamp of the database creation
  4. The current log sequence number
  5. Checkpoint information
  
  -Dropping Control Files - You want to drop control files from the database, for example, if the location of a control file is no longer appropriate. Remember that the database should have at least two control files at all times.
  
  1. Shut down the database.
  2. Edit the CONTROL_FILES parameter in the database initialization parameter file to delete the old control file name.
  3. Restart the database.
  
  - Creating Initial Control Files - The initial control files of an Oracle Database are created when you issue the CREATE DATABASE statement.
  - The names of the control files are specified by the CONTROL_FILES parameter in the initialization parameter file used during database creation.
  - The filenames specified in CONTROL_FILES should be fully specified and are operating system specific.
  
  - Creating Additional Copies, Renaming, and Relocating Control Files - You can create an additional control file copy for multiplexing by copying an existing control file to a new location and adding the file name to the list of control files.
  - Similarly, you rename an existing control file by copying the file to its new name or location, and changing the file name in the control file list.
  - In both cases, to guarantee that control files do not change during the procedure, shut down the database before copying the control file.
  
  - Creating new control files - It is necessary for you to create new control files in the following situations:
  1. All control files for the database have been permanently damaged and you do not have a control file backup.
  2. You want to change the database name.
  3. The compatibility level is set to a value that is earlier than 10.2.0, and you must make a change to an area of database configuration that relates to any of the following parameters from the CREATE DATABASE or CREATE CONTROLFILE commands: MAXLOGFILES, MAXLOGMEMBERS, MAXLOGHISTORY, and MAXINSTANCES. If compatibility is 10.2.0 or later, you do not have to create new control files when you make such a change; the control files automatically expand, if necessary, to accommodate the new configuration information.

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