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Maintaining the Control File:

Maintaining the Control File


Objectives After completing this lesson, you should be able to do the following: Explain the uses of the control file List the contents of the control file Multiplex and manage the control file Manage the control file with Oracle Managed Files (OMF) Obtain control file information

Control File :

Control File A small binary file Defines current state of physical database Maintains integrity of database Required: At MOUNT state during database startup To operate the database Linked to a single database Loss may require recovery Sized initially by CREATE DATABASE Control files Database

Control File Contents :

Control File Contents A control file contains the following entries: Database name and identifier Time stamp of database creation Tablespace names Names and locations of datafiles and redo log files Current redo log file sequence number Checkpoint information Begin and end of undo segments Redo log archive information Backup information

Multiplexing the Control File :

Multiplexing the Control File CONTROL_FILES= $HOME/ORADATA/u01/ctrl01.ctl, $HOME/ORADATA/u02/ctrl02.ctl Disk 1 (u01) Disk 2 (u02) ctrl02.ctl ctrl01.ctl

Multiplexing the Control File When Using SPFILE:

Multiplexing the Control File When Using SPFILE Alter the SPFILE : Shutdown the database: 3. Create additional control files: 4. Start the database: ALTER SYSTEM SET control_files = '$HOME/ORADATA/u01/ctrl01.ctl', '$HOME/ORADATA/u02/ctrl02.ctl' SCOPE=SPFILE; cp $HOME/ORADATA/u01/ctrl01.ctl $HOME/ORADATA/u02/ctrl02.ctl startup shutdown immediate

Multiplexing the Control File When Using PFILE:

Multiplexing the Control File When Using PFILE Shut down the database: Create additional control files: Add control file names to PFILE : Start the database: shutdown immediate CONTROL_FILES = (/DISK1/control01.ctl, /DISK3/control02.ctl) cp $HOME/ORADATA/u01/ctrl01.ctl $HOME/ORADATA/u02/ctrl02.ctl startup

Managing Control Files with OMF:

Managing Control Files with OMF OMF created if the CONTROL_FILES parameter is not specified Locations are defined by DB_CREATE_ONLINE_LOG_DEST_n Names are uniquely generated and displayed in the alertSID.log

Obtaining Control File Information :

Obtaining Control File Information Information about control file status and locations can be retrieved by querying the following views. V$CONTROLFILE : Lists the name and status of all control files associated with the instance V$PARAMETER : Lists status and location of all parameters V$CONTROLFILE_RECORD_SECTION : Provides information about the control file record sections SHOW PARAMETER CONTROL_FILES : Lists the name, status, and location of the control files


Summary In this lesson, you should have learned how to: Multiplex the control file when using an SPFILE Multiplex the control file when using an init.ora Manage the control files using OMF

Practice 6 Overview:

Practice 6 Overview This practice covers the following topics: Starting the database without a control file Multiplexing an existing control file

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