The Backup Once Wizard is intended as a supplement to regularly scheduled backups, not as a substitution for them. For example, you can use the Backup Once Wizard for the following situations:
Volumes or folders that are not included in regular backups
Volumes or folders that are part of the regular backup but that contain important items that should be backed up immediately before making changes that will affect them
Backups of regularly scheduled items to a location other than where scheduled backups are stored
If you are using a local disk, be sure the disk supports either USB 2.0 or IEEE 1394 (if external) or is attached to the server. If using DVDs, make sure that a DVD writer is connected to the server and online, ...