RMAN Backup type (Differential & Cumulative)

RMAN backup types

RMAN incremental backup for an Oracle DB

Sometimes we need to backup the database changes only from the last backup (only the last changes are backed up). This is an incremental backup. There are 2 types of incremental backup: DIFFERENTIAL (by default) & CUMULATIVE.

NOTE: The incremental backups are only for the DATA files.




DIFFERENTIAL backup = which backs up all blocks changed after the most recent incremental backup at level 1 or 0. (See Picture 1). The following RMAN command is used to take a DIFFERENTIAL database backup:

RMAN> BACKUP INCREMENTAL LEVEL 1 DATABASE;






CUMULATIVE backup =  which backs up all blocks changed after the most recent incremental backup at level 0. (See Picture 2)
The following RMAN command is used to take a CUMULATIVE database backup:

RMAN> BACKUP INCREMENTAL LEVEL 1 CUMULATIVE DATABASE;


The advantages of each types of incremental backup



Here are the advantages of each types of incremental backup:


Advantages of the DIFFERENTIAL backup
 

• Less space disk used
• Less network traffic
• Less time to take a backup

Advantages of the CUMULATIVE backup

• Less time to recover