7遍或35遍擦除如何工作?为什么要使用这些方法? [英] How does a 7- or 35-pass erase work? Why would one use these methods?

问题描述

7遍和35遍擦除如何以及为何起作用? 一个全为零的简单重写就不够了吗?

How and why do 7- and 35-pass erases work? Shouldn't a simple rewrite with all zeroes be enough?

推荐答案

我从没听说过擦除35部分的内容: http://en.wikipedia.org/wiki/Gutmann_method

I'd never heard of the 35-part erase: http://en.wikipedia.org/wiki/Gutmann_method

Gutmann方法是一种用于 安全删除其中的内容 计算机硬盘驱动器，例如文件. 由Peter Gutmann和Colin设计 铅垂，它通过编写一系列来做到这一点 该区域内的35种图案 已删除.模式的选择 假设用户不知道 驱动器使用的编码机制， 包括设计的图案 专为三种不同类型 的驱动器.知道哪种类型的用户 驱动器使用的编码方式可以选择 只有那些针对他们的模式 驾驶.具有不同驱动器 编码机制将需要 不同的模式.大部分的 古特曼方法中的模式是 为较旧的MFM/RLL编码而设计 磁盘.相对较新的驱动器否 不再使用较旧的编码 技术，使许多 古特曼指定的模式 多余的.[1]

The Gutmann method is an algorithm for securely erasing the contents of computer hard drives, such as files. Devised by Peter Gutmann and Colin Plumb, it does so by writing a series of 35 patterns over the region to be erased. The selection of patterns assumes that the user doesn't know the encoding mechanism used by the drive, and so includes patterns designed specifically for three different types of drives. A user who knows which type of encoding the drive uses can choose only those patterns intended for their drive. A drive with a different encoding mechanism would need different patterns. Most of the patterns in the Gutmann method were designed for older MFM/RLL encoded disks. Relatively modern drives no longer use the older encoding techniques, making many of the patterns specified by Gutmann superfluous.[1]

也很有趣:

一种恢复数据的标准方法 已被覆盖在硬盘驱动器上 是捕获模拟信号 在驱动器磁头读取之前 被解码.该模拟信号将 接近理想的数字信号， 但是区别是什么 重要的.通过计算理想 数字信号然后减去它 从实际的模拟信号是 可能忽略了最后 书面信息，扩大 剩下的信号，看看是什么 之前写过.

One standard way to recover data that has been overwritten on a hard drive is to capture the analog signal which is read by the drive head prior to being decoded. This analog signal will be close to an ideal digital signal, but the differences are what is important. By calculating the ideal digital signal and then subtracting it from the actual analog signal it is possible to ignore that last information written, amplify the remaining signal and see what was written before.

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