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What Does Undelete Mean?

Undelete refers to the process used to recover computer files, text, or data that have been discarded or deleted. When you delete a file, it may still reside on the hard drive somewhere; if so, you may be able to undelete it.


Techopedia Explains Undelete

Temporary data file folders or directories may be referred to by different names, depending on the operating system or software application. When files are deleted from a temporary storage location, undeleting the data becomes more difficult, or even impossible.

In a File Allocation Table (FAT)16 file system, an undelete function is supported. Whenever a file is deleted, the file system keeps the directory entry with all the related information, including physical location, timestamp, name, and length. Only the file allocation table is updated to mark those sectors as available for reuse by other files. This directory entry is used by FAT16 system software to undelete a file. In general, you have a better chance of undeleting a file in a FAT16 file system than in a FAT32 file system. Most modern UNIX file systems, with the exception of AdvFS, do not support undeletion.

An OS or application undelete feature can pose security risks. For example, a user with network access may be able to retrieve a previous user’s inadvertently-stored sensitive information.

Even if data recovery personnel and programs are established, it may not be possible to recover deleted data unless the following criteria are met:

  • The deleted file entry exists in the folder or directory and has not been overwritten by another file or file version.
  • Data storage drive sectors have not been overwritten by other files.
  • Files are not fragmented.

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Margaret Rouse
Technology Expert
Margaret Rouse
Technology Expert

Margaret is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical business audience. Over the past twenty years, her IT definitions have been published by Que in an encyclopedia of technology terms and cited in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine, and Discovery Magazine. She joined Techopedia in 2011. Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages.