Use the -extension flag to prevent overwriting by restoring data into a new volume. If the name of the ReadWrite version of a volume is provided, the Backup System automatically appends a .backup extension to the name. It then determines which version of the volume was dumped most recently, the Backup or the ReadWrite, and restores that version. If a .backup or .readonly extension is provided with the name of the volume, the Backup System restores only that version of the volume. This causes the Backup System to restore the data from tape into a new volume, distinct from the existing one.
Any string is acceptable except .readonly or .backup.
If a period is to precede the extension, include it in the string provided. Only dumps dated before -date are restored. The instance can have one of two legal values. A value of this type causes a date-specific restore containing data only from dumps done before the indicated date and time. Port offsets must be paired with dump levels.