APPLIES TO:
Zero Data Loss Recovery Appliance Software - Version 12.1.0.1.0 and later
Information in this document applies to any platform.
PURPOSE
This bulletin will advise DBAs about best practices for RMAN backup commands that are handled most efficiently by the Recovery Appliance.
SCOPE
RMAN database backups that will be stored on the Recovery Appliance
DETAILS
The Recovery Appliance provides an Incremental Forever backup strategy that receives Incremental Level 1 backups and converts them into Virtual Level 0 backups. However, the Recovery Appliance can also receive traditional Full Backupsets, which will not be converted into Virtual Level 0 backups. Using the correct type of backup for the desired business goal will best utilize the resources on the Recovery Appliance.
Controlfile Autobackups
Controlfile Autobackups provide a means for automatically creating a backup of the current controlfile at the end of an RMAN backup operation. RMAN can then restore a controlfile autobackup from the Recovery Appliance by searching for the special naming convention defined for autobackups.
Incremental Forever backup strategy
The Recovery Appliance's premier feature is the ability to convert Incremental Level 1 backups into Virtual Level 0 backups. These Virtual Level 0 backups allow the database to be restored to different times within the Recovery Window offered by the appliance, and requiring a minimal amount of Media Recovery.
The best practice RMAN command to implement an Incremental Strategy is
backup device type sbt cumulative incremental level 1 filesperset 1 section size 64g database plus archivelog filesperset 32 not backed up;
Each backup piece received by the Recovery Appliance will contain one datafile, and therefore the Recovery Appliance can begin converting each datafile's backup to a Virtual Level 0 immediately as it is finished. Since the Recovery Appliance can process up to 78 tasks concurrently on a ZDLRA X5 system and up to 88 tasks concurrently on a ZDLRA X6 system, the data files will be indexed quicker and the overall time from the start of the backup to the time that the last Virtual Full backup is created is shorter.
Note that the best practice RMAN command is not the default used by Cloud Control. To implement the best practice, under the "Schedule Backup..." UI, select "Schedule Customised Backup" and on the final page of the UI, click Edit Script and then replace the suggested command with the recommended backup command above.
An alternative RMAN backup script that we often see used, but which is not a best practice, is
backup incremental level 1 cumulative section size 64g device type sbt database;
backup device type sbt archivelog all not backed up;
When this script is used, the Recovery Appliance is able to process the backup pieces received from the protected database, but the length of time between the start of the backup and the time that the Virtual Level 0 backups are available will be longer than the best practice command, because the Recovery Appliance must wait for the backup piece, which may consist of up to 64 datafiles, to be completed before the Recovery Appliance can begin to convert the Incremental Level 1 backup into a new Virtual Level 0 backup.
Full Backupset backup strategy
Sometimes it is necessary to use the Recovery Appliance as a means to instantiate a standby or dev/test database, or to aid in migrating a database from one system to another. In such cases, there is no need to create an Incremental Forever strategy for this purpose because the backup will be used once and then deleted.
The backup command that should be used to facilitate this type of operation should be
backup device type sbt database;
With such a command, the Recovery Appliance simply stores the database backup in the Storage Location, but no Virtual backup is created. This is desirable when it comes to deleting this backup from the Recovery Appliance or deleting the database from the Recovery Appliance, as the operations that the appliance needs to perform are simpler.