Abstract: The present invention provides a real-time backup method for single storage medium which partitions a single storage medium into multiple logic units, and then the logic unit is designated as a backup logic unit or a normal storage logic unit, and the backup logic unit is partitioned into two or more unit blocks. Data with backup demand are simultaneously written into two individual stripe blocks belonging in the two selected unit blocks respectively in the backup logic unit for real-time backup function. Therefore the storage medium is used efficiently and the real-time backup function is achieved.