RMAN provides multiple backup types, but the most commonly used in production environments are Full backups and Incremental backups. Understanding their differences helps DBAs design efficient backup strategies that optimize storage, speed, and recovery time.
1. Full Backup
A Full Backup (or Level 0 backup) is a complete backup of the entire database.
Key Characteristics
Backs up all data blocks, regardless of whether they changed.
Forms the baseline for incremental backup strategies.
Larger in size than incremental backups.
Takes more time and requires more storage.
Recovery is straightforward—restore full backup + apply archived logs.
2. Incremental Backups
Incremental backups only capture blocks that have changed since a previous L0 backup.
RMAN supports two types:
Differential Incremental Backup (Level 1 Differential)
Cumulative Incremental Backup (Level 1 Cumulative)
Both rely on a Level L0 full backup as a baseline.
2.1. Differential Incremental Backup
A Differential Level 1 backup captures all blocks changed since the last backup (Level 0 or Level 1).
Key Characteristics
Smaller and faster than full backups.
Captures daily changes.
During recovery, RMAN may use multiple Level 1 backups.
When it comes to recovery we need L0 Backup and all L1 backups including Archive logs need to be apply.
2.2. Cumulative Incremental Backup
A Cumulative Level 1 backup captures all blocks changed since the last Level 0.
Key Characteristics
Slightly larger than differential backups.
Faster recovery (fewer incremental files to apply).
Preferred for large, mission-critical systems.
When it comes to recovery we need L0 and recent L1 Cumulative backup including Archive logs need to be apply.
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