a fast destruction (standard 1-round filling of random data) = 快速模式 (覆寫1次)
a forced destruction (3 rounds of filling according to DoD 5220.22M standard) = 一般模式 (覆寫3次)
an ultimate destruction (35 rounds of filling with data according to Guttman algorithm) = 究極模式 (覆寫35次)