Oracle provides the Recovery Manager utility (RMAN) to perform two types of database backups: Image Backup and Backup Set.    RMAN command BACKUP AS COPY command creates an image copy or bit for bit copy of the data files, archived redo log and controlfiles.

 

RMAN> BACKUP AS COPY DEVICE TYPE DISK DATABASE;

 

You can set the default backup to image copy with CONFIGURE DEVICE TYPE command

 

RMAN> CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO COPY;

 

Backup sets are the other type of RMAN backups, each backup set has one or more binary files called backup pieces, in proprietary format that can be restored by RMAN.  You can limit the size of size of backup pieces by the MAXPIECESIZE option.   Use the RMAN command BACKUP AS BACKUPSET to create backup copy of database.

 

RMAN> BACKUP AS BACKUPSET DATABASE.

 

You can set the default backup to backup set with the CONIFGURE DEVICE TYPE command.

 

RMAN> CONFIGURE DEVICE TYPE DISK BACKUP TYPE TO BACKUPSET;

 

You can backup the entire database with the command:

 

RMAN> BACKUP DATABASE;

 

Add PLUS ARCHIVELOGS clause will cause a log switch that allows for full media recovery to the point of starting the backup.

 

RMAN> BACKUP DATABASE PLUS ARCHIVELOG;

 

Incremental Backups are part of a backup set that only contains changes to the database since the last full backup.   The benefit of an incremental backup is size of the backup and time required to tack the backup.   Incremental Backups are only good if combined with the last full backup and any incremental backup between the last full backup.

 

You can create an incremental backup with the RMAN command BACKUP INCREMENTAL in three ways

 

Level 0 – Identical to full back

Level 1 Differential – backups all changed blocks since most recent incremental backup.

Level 1 Cumulative – backups all changed block since most recent Level 0 incremental backup

 

Restoring incremental backup use level 0 at start and apply level 1 cumulative or all differential.

 

Example of incremental Level 1:

 

RMAN> backup incremental level 1 cumulative database;

 

RMAN> backup incremental level 1 database;

 

 

Larry Catt

OCP