Oracle RMAN Pocket Reference

Parallelism of backups

In order to improve performance, RMAN can break out certain commands and use multiple, parallel processes to execute the issued command. This does not mean that if you issue five RMAN commands, RMAN will try to parallelize and run those five commands at the same time, but rather that each individual command will be parallelized.

A good example of parallelization is using a backup command. If you allocate multiple channels, RMAN simultaneously uses multiple processes to work on the command, writing data simultaneously through all channels:

RMAN> configure device type disk parallelism 3;
RMAN> backup database format '/d99/rmanback/rman_%U.bus';

In effect, this uses three concurrent processes to back up the database.