The backup and restore functions are designed to help you recover from an emergency situation where an erroneous configuration update renders the respective configuration resource useless. This event is unlikely and can normally be rectified by first returning to the customization and then repeating the update tasks with corrected customization data.
Some services that maintain critical configuration resources provide backup and restore as an extra recovery path. For example, backup is provided for the msys for Setup parmlib and the couple data sets. See Back up configuration data for more details. To find out if a service provides backup consult the respective service informtion file.
Use the restore function if you cannot IPL your system because of a failing critical resource. IPL your system with the emergency member and then run the restore task for the affected service. By returning to an older version of some configuration resources the restore causes the management directory and the actual configuration to be out of sync. After the restore, you must refresh the management directory for the affected services and then correct the configuration. See Restore configuration data for more details.