About the Recovery Appliance Incremental-Forever Backup Strategy

While Recovery Appliance can support many different RMAN backup strategies, Oracle strongly recommends using the incremental-forever backup strategy to back up protected databases. This strategy is based on an initial level 0 incremental backup followed by successive level 1 cumulative incremental. Enabling real-time redo transport to the appliance is recommended, so that archived log backups are automatically created by and stored on the appliance. Apart from the initial full backup, no regular full backups are required. This eliminates traditional backup windows and improves protected database performance.

For each protected database, Recovery Appliance regularly receives scheduled level 1 incremental backups consisting of only the data file block changes relative to the most recent virtual full backup (recorded as level 0 in the recovery catalog). The level 1 backups are validated to ensure that there are no corrupt data blocks, compressed using specialized block-level algorithms, and then written to a storage pool on the Recovery Appliance. Virtual full backups are created based on the incoming incremental backups. When you need to recover the protected database, Recovery Appliance uses virtual full backups and archived log backups that together allow the recreation of all database changes until the specified recovery time.

When incremental backups are mistakenly taken to DISK or other SBT destinations, this can create a gap in the incremental backup strategy preventing the creation of a new virtual full.

Smart incremental backups works with RMAN to create the needed incremental backups in order to properly maintain the virtual backup lineage. This feature also allows new Transparent Data Encrypted (TDE) databases, and re-key or master key rotation of existing TDE databases to continue with the incremental forever backup strategy for creating virtual full backups on the Recovery Appliance. Smart incremental backups are enabled by default.

Note:

RMAN sparse backups are not supported with incremental forever strategy.

Oracle recommends that you take frequent backups of the archived redo log files and include them in both full and incremental backups. Even with real-time redo, the recommended L1 incremental backup script includes archived logs that have not yet been backed up as a safety measure just in case some logs were not sent due to a Recovery Appliance outage. Alternatively, you can use RMAN to backup archived logs to the Recovery Appliance.

Note:

"About Real-Time Redo Transport"

Difference Between RMAN Incrementally Updated and Recovery Appliance Incremental-Forever Backup Strategies

There are important differences between the incremental strategy used in a conventional RMAN setup and the incremental-forever backup strategy used with Recovery Appliance:

  • The RMAN incrementally updated backup strategy uses an initial image copy, followed by successive level 1 incremental backups. The image copy is then updated by merging the level 1 incremental backups with the image copy.

    Following is an example of a script that is used to implement the RMAN incrementally updated backup strategy:

    run
{
    RECOVER COPY OF DATABASE
       WITH TAG 'incr_update';
    BACKUP
       INCREMENTAL LEVEL 1
       FOR RECOVER OF COPY WITH TAG 'incr_update'
    DATABASE;
}

  • With the Recovery Appliance incremental-forever backup strategy, only one level 0 incremental backup is required. Subsequently, level 1 incremental backups are created and stored on the Recovery Appliance. A virtual full backup is created by referencing blocks from the initial level 0 and subsequent level 1 backups.

    Following is an example of a script that implements the Recovery Appliance incremental-forever backup strategy:

    BACKUP CUMULATIVE INCREMENTAL LEVEL 1
     DEVICE TYPE sbt FORMAT '%d_%U' TAG '%TAG'
     DATABASE;
BACKUP DEVICE TYPE sbt FORMAT '%d_%U' TAG '%TAG'
     ARCHIVELOG ALL NOT BACKED UP;