A flash memory system including one or more flash memory devices; the flash memory devices are partitioned into multiple units, at least a first unit and a second unit. A mechanism which allocates the units in combination as a super-unit, reserves at least a portion of a first unit field required for managing the super-unit in the first unit and the mechanism reserves at least a portion of a second unit field required for managing the super-unit in the second unit. Preferably, the first unit field and the second unit field are different unit fields, or the first unit field and the second unit field are the same unit field. Preferably, the flash memory device each support at least two planes, and the first unit and the second unit each belong to a different plane. Alternatively, there are two flash memory devices, and the first unit and the second unit each belong to a different flash memory device.