RDF System Management Manual for J-series and H-series RVUs (RDF Update 13)

If TMF BEGINTRANS is disabled, RDF issues an error message.
Unless you explicitly specify otherwise, RDF always starts with updating enabled: all updater
processes immediately begin updating their volumes by reading audit images from the RDF image
files and applying the appropriate changes to the backup database files.
If you want to start RDF with the updater processes disabled, you should specify the UPDATE OFF
attribute in the START RDF command on the primary system:
]START RDF, UPDATE OFF
If you later want to start the updater processes, you merely issue a START UPDATE command.
Restarting the Applications
As the final step in establishing an RDF environment, if you had shut down your applications
previously, you can restart them now.
Enabling RDF Operations 87