Day 5: Configuring ARCHIVELOG Mode

Posted by Paola Pullas | Posted in Administración, Base de Datos, Oracle | Posted on 05-09-2010

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Configuring the Flash Recovery Area

The flash recovery area is a storage location for all recovery related files. All files that are needed to completely recover a database from a media failure are part of the flash recovery area. Some files in the flash recovery area are: control files, redo logs, archived logs, backup pieces, image copies, flashback logs and foreign archived logs.

By allocating a storage location and unifying related recovery files within a specific area, the Oracle database server relieves the database administrator from having to manage the disk files created by these components.

When setting up a flash recovery area, you choose a directory, file system or Automatic Storage Management disk group to hold the files, and set a disk quota for the maximum space to be used for all files stored in the flash recovery area.

The flash recovery area should be on a separate disk from the working area. Keeping the flash recovery area on the same disk as the working area exposes you to loss of both your live database files and backups in the event of a disk failure.

You can execute the next command from SQL*Plus in order to verify the actual configuration of flash recovery area:

  • show parameter db_recovery_file_dest

If you want to change this configuration you can execute the alter system command from SQL*Plus to set the values that are more appropriate for your environment:

  • alter system set db_recovery_file_dest='/u01/app/oracle/flash_recovery_area' scope=both;
  • alter system set db_recovery_file_dest_size='2G' scope=both;

The first parameter shows you the physical directory of the flash recovery area and the second parameter shows you the quota or size assigned for this area. Keep in mind that quota should be bigger enough to keep the recovery files.

Another method to verify the flash recovery area configuration is using Enterprise Manager Dbconsole going to Availability –> Recovery Settings like I show you in the next screens.

Configuring the Archivelog Mode from SQL*Plus

The firs step is make a clean shutdown of your database using any of the next commands from SQL*Plus:

  • shutdown immediate;
  • shutdown normal;
  • shutdown transactional;

Then you should use the next commands from SQL*Plus in order to mount the database, configure the archivelog mode and finally open the database:

  • alter database mount;
  • alter database archivelog;
  • alter database open;

Next I will verify if my configuration is working properly with the next commands:

  • select log_mode from v$database;
  • alter system archive log current;

In the first screen the command verify the log mode of the database and in the second screen I am forcing the archiving process in the database:

Configuring the Archivelog Mode from Enterprise Manager Dbconsole

Login in Enterprise Manager Dbconsole page.

Go to Recovery Settings link under Availability tab.

Go to Media Recovery section and check the ARCHIVED Mode option then click in Apply button.

A Confirmation screen will appear after click in Apply button, then click in Yes button.

The next screen will appear and you should fill the text boxes with the os and database users information, in my case the os user is oracle and the database user with SYSDBA privilege is sys, then click in OK button.

The next screens will appear after this operation. You should wait a few minutes until the process finished. In order to know that this complete successfully you should refresh your browser until the login screen appears.

Author: Paola Pullas
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