Oracle RMAN Staging Job Types

There are three types of Oracle RMAN backup staging jobs:

Master Job

A backup job is a master job.

RMAN Dummy Job

Every Oracle database instance has a RMAN dummy job and the description of the RMAN dummy job contains the database instance name. It is as follows:

STAGING [JOB **] RMAN DUMMY SUBJOB *, Source [hostname (***.***.***.*** ) Oracle:Instance_name], [the description from master job]

After a backup job is launched, the master job tries to reserve the media for every database instance according to the backup settings. When the master job reserves enough media for an instance, it will create a dummy job to handle the backup for this instance, and then it will continue to reserve media for the next instance.

If the number of dummy jobs is not equal to the number of instances, it means the master job cannot reserve enough media for all instances. In this scenario, depending on what was specified for the Device availability waiting time (minutes) setting, some instances have to wait until other instances finished or a timeout will occur.

RMAN Child Job

Every RMAN backup channel has a corresponding RMAN child job. The description of the RMAN child job is as follows:

STAGING [JOB xx] SUBJOB x, Source [hostname (***.***.***.***)], the description from master job.

The child jobs can be reused between different database instances after the previous one is done and there are other pending instances. This usually happens when the number of maximum streams is small and all of the instances cannot start to back up at the same time.