DBA

Control File :-

* Small Binary file necessry for the database to start and operate successfully.

* Each Control file associated with only one database.

* Before database opened, the control file is read to determine if the database is in a valid state to use.

* Control file is updated continously by the oracle server.

* It must be available for writing whenever the database is open.

* No databse administrator or end user can not edit this file.

* If all copies of a control file lost, the database must be recovered before database opened.

* Control file should be multiplexed upto eight times.

Control Files Contents :-

• Database name and identifier
• Time stamp of database creation
• Tablespaces names
• Names and locations of datafiles and redolog files.
• Current redo log file sequence number.
• Checkpoint information
• Begin and end of undo segments
• Redo log archive information
• Backuop information.

sql> show parameter control_files;

Multiplex control files using pfile

(alreay have two control files and then)

sql> Alter system set control_files= '\oracle\oradata\{sid}\control01.ctl',

'\oracle\oradata\{sid}\control02.ctl','\oracle\oradata\{sid}\control03.ctl' scope = spfile ;

system altered.

sql> show parameter control_files;

***** Now not effet right now and so you shutdown the database and startup manually and copy the controlfile os level and paste it and rename it.

(control01.ctl (copy) and paste it same location (copy of control01.ctl ) and then rename it (control03.ctl))

sql>shutdown immediate

copy and paste and rename it

sql> startup

Sql> show parameter control_files;

Backup the control file :-

sql> Alter database backup controlfile to 'filename';

sql>alter database backup controlfile to trace;

View :-

• v$controlfile
• v$parameter
• v$controlfile_record_section
• show parameter control_files
• v$backup
• v$datafile
• v$tempfile
• v$tablespace
• v$archive
• v$log
• v$logfile
• v$loghist
• v$archived_log
• v$database