Archive mode and non-archive mode Oracle 10g Learning Series (4)

First, the archive mode:

The Oracle database has an online redo log, which records changes made to the database, such as inserting, deleting, updating data, etc., which are recorded in the online redo log. A generic database must have at least 2 online redo log groups. When an online redo log group is written full, a log switch occurs, the online redo log Group 2 becomes the currently used log, when the online redo log Group 2 is full, the log switch, to write online redo log Group 1, so repeated.

If the database is in non-archive mode, the online log is discarded when it switches. In archive mode, when a log switch occurs, the log that is toggled is archived. For example, in the current use of online redo log 1, when 1 is full, a log switch occurs, start to write online redo log 2, the contents of online redo log 1 will be copied to another specified directory. This directory is called the Archive directory, and the copied files are called archive redo logs.

A database can be run with an archive for catastrophic recovery.

Second, non-archiving mode

Conversely, non-archiving means not saving the old transaction log.

Iii. differences between archived log mode and non-archived log mode

Archive mode can do hot backup, and can do incremental backup, can do partial recovery.

Non-archive mode only makes cold backups, and only full backups can be made when recovering. Data cannot be recovered during the last full backup to system error.

Four, in order to make the Oarcle database automatic log file, need to do two things;

1. Is the setting of the database logging mode (available for Archive mode and no Archive mode);

2. is the auto-archive mode setting (Automatic archival, which is enabled and disabled).

V. Open archiving mode for Oracle database

Sqlplus>select Log_mode from V$database;

Log_mode

------------------------------------

Noarchivelog

Show archive mode not turned on

Data Backup before change:

To manually export an Oracle database command:

Exp System/manager file=e:\back.dmp full=y

1. Connection

Linux/unix System:

Rman Target/nocatalog;

Sqlplus/nolog

Conn/as Sysdba;

2. Open Archive

Sqlplus>shutdown immediate; (To stop the database before starting the archive)

Sqlplus>startup Mount; (database starts in Mount mode)

Sqlplus>alter database Archivelog; (starting a DB archive)

Sqlplus>alter database open;

Sqlplus>archive log list; (see if the archive is already open)

Database Log Mode Archive mode

Automatic Archival Enabled

Sqlplus>select archiver from V$instance;

Archiver

---------------------

STARTED

View Archive log file path

Sql> Show Parameter Db_recovery_file_dest

This article is from "Kaka West" blog, please be sure to keep this source http://whnba.blog.51cto.com/1215711/1596029

Archive mode and non-archive mode Oracle 10g Learning Series (4)