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Simson Garfinkel researches computer security, privacy and digital forensics. With Abhi Shelat, he studied whether used hard disk drives retained readable information after disposal or resale. Their 2003 paper transformed a general concern about confidentiality into an investigation of actual storage devices.^[ref]

The researchers acquired 158 drives between November 2000 and August 2002, recorded their provenance and examined copied device contents. Some drives were damaged or unreadable; others retained recoverable data. The paper distinguishes ordinary access through a file system from information remaining outside its live names and records. It also cautions that the sample does not establish a population-wide prevalence.^[ref]

An original storage example makes the distinction concrete. Suppose a toy file system holds a document in four 512-byte file data blocks. Removing its name from a file-system directory and marking those blocks reusable can leave all $4\times 512=2048$ content bytes unchanged. The file deletion changed live bookkeeping, while this stipulated model performed zero overwrites of the document's contents. Other file systems can behave differently, but disappearing from a directory listing alone does not prove data sanitization.

The experiment motivates testing a storage claim at the level it concerns: absence of a live filename and absence of recoverable former content are different observations.