When phasing out the use of hard disk and other devices storing digital data, for ordinary users, the private data inside should be erased effectively in order to avoid the abuse or leakage of privacy made by people with ulterior motives; for enterprises and institutions, the data is often very important, sensitive and confidential, so that they must be destroyed strictly. To do this, we have to turn to some third party professional data sanitizing tools, because deleting the data itself and formatting the entire disk are all futile.