# Recovering disk data

**URL:** <https://boards.straightdope.com/t/recovering-disk-data/498819>\
**Category:** Factual Questions\
**Created:** [June 5, 2009, 2:19pm UTC](https://boards.straightdope.com/t/recovering-disk-data/498819 "2009-06-05T14:19:11Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Vorpal\_Blade](https://avatars.discourse-cdn.com/v4/letter/v/9de0a6/32.png) [@Vorpal\_Blade](https://boards.straightdope.com/u/Vorpal_Blade)\
**Post date:** [June 5, 2009, 2:19pm UTC](https://boards.straightdope.com/t/recovering-disk-data/498819/1 "2009-06-05T14:19:11Z")

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In discussions of how “deleted” files can be recovered, reference is made to the fact that legible, albeit faint, traces of old files can be detected (presumably using esoteric methods and equipment) in such wise as to recover the underlying data, even after it’s been overwritten several times.

Here’s my question. How can this be? Surely a device sensitive enough to read a “faint trace” would be overwhelmed by the much stronger freshly-written data overlaying it.

What’s the trick?

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**Author:** ![Kyrie\_Eleison](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kyrie_eleison/32/7682_2.png) [@Kyrie\_Eleison](https://boards.straightdope.com/u/Kyrie_Eleison)\
**Post date:** [June 5, 2009, 3:17pm UTC](https://boards.straightdope.com/t/recovering-disk-data/498819/2 "2009-06-05T15:17:57Z")

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[This](http://www.usenix.org/publications/library/proceedings/sec96/full_papers/gutmann/index.html) is probably the most often cited paper on the topic.