Oracle 11g Management control files

Oracle database control files are very important files, which are automatically generated binaries when the database is created, which records the status information of the database, mainly including the following content

? Name of the database, a control file can belong to only one database

? Database creation Time

? Name, location, online, and offline status information for the data file

? Redo log file name, location, and archive information

? All Table space Information

? Current log sequence number

? Recent Checkpoint Information

The control file is read in the Mount stage of the database startup, and when the database is started, the default rules are used to locate and open the parameter file, the parameter file contains the location information of the control file, and when the control file is opened, the database is opened by controlling the location of the various database files recorded in the file. To start the database to a usable state. When the database is successfully started, the database server can continuously modify the contents of the control file during the database operation, so the control file must be read-write during the database being opened. However, no other user can modify the control file, only the instance of the database is able to modify the information in the control file.

View Control file information, you can view control file information from the V$controlfile view, control file name

In addition to viewing control file information from the V$controlfile view, you can view it from the V$parameter view

How to view content information that is stored in a control file

You can use V$controlfile_record_section

View V$controlfile_record_section in type,record_size,records_total,records_used

From there, you can see information such as database creation, redo log information, data files, and archived log file records in the control file. These valuable information is used for data maintenance and management, and many data dictionary views are information obtained from control files.

Storing multiple control files

Because the control file is very important, so require control files can not only one, usually more than 3 control files in the database, and stored on different disks, this method of using control files is also known as control file multiplexing. One way to achieve multiple is to include all control file names by copying the control file to multiple locations and modifying the Control_files parameter in the initialization parameter file. It is important to note that when there are multiple control files, Oracle updates all control files at the same time, but only reads the first control file enumerated in Control_files.

Examples of ways to implement a multiplexed control file:

The database state is open, modify the Control_files parameter in the SPFile


Close the database

To copy a file to a new location by using the operating system command

Restarting an instance

Backup control files

Backup control files

To ensure the security of the database, the control files are backed up when data file or log file location information changes, such as when adding data files to the tablespace. There are two ways to backup: Backup as a binary file and back up as a script file

An example of how to back up a binary file:

Before you back up the control file, check that there are several control files in the current system

Backup control files

Modify System Parameters File

ORA-00214 error is reported after database has been shut down since the control file version inconsistency is responsible for

The Control01.ctl control file version is 817, and the Control02.ctl version is 806.

Use Control01.ctl to overwrite the control03.ctl, so that the control file version remains consistent.

Close the database

You can restart the database.

Recovery control files

Assuming that the control file specified by Controld_files is corrupted, but you can also access the control file in the data dictionary, you can restore it using the following steps:

To close a DB instance

Delete a control file

Start the database

The state of the database at this time is

Use the operating system to overwrite the corrupted control file with the intact control file

Close the current database

Restarting a DB instance

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Oracle 11g Management control files