In Computing, what does "Undelete" Mean?

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  • Written By: Andrew Kirmayer
  • Edited By: Angela B.
  • Last Modified Date: 20 May 2020
  • Copyright Protected:
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When you delete a file from your computer and then empty your computer's recycling bin, it seems as if there’s no way to recover that file. It is possible, however, to undelete almost any file, all of which are saved on the computer's hard drive even after you have intentionally deleted them and after it appears data have been lost. On the Windows® 98 operating system, the File Allocation Table (FAT) lists where a deleted file is still being used on the drive, even though you think it’s not there. Operating systems such as Windows® Vista with a Master File Table (MFT), instead of the FAT, can similarly find files and related data storage clusters on the disk drive. It is because of this setup that files can still be recovered.

There are several file recovery and computer disaster recovery software programs that can find data you thought was gone forever. Such programs do a search on your hard drive for FAT or MFT entries. Once the deleted file is located, the software scans the rest of the table to see whether other locations, or clusters, on the disk previously used by the deleted file are being used by other files. If so, the file you’re looking for was probably overwritten and you’ll never see it again. There are programs that can undelete files in Apple® Macintosh operating systems in a similar way.

It is possible to recover files after a computer crash, because the system saves them even after the recycling bin is emptied. The deleted files are specially marked in the MFT, indicating the clusters that were occupied by it are empty. In Windows®, the content of these indicated clusters is untouched, so the data stored there still exist, even if the file has been deleted or the system has crashed. Using software to undelete deleted files is the most popular method of file retrieval. The best way to use the program is to load it directly from a compact disk (CD) or flash drive without installing it on the hard disk.

There are also professional data recovery services that can undelete files on your computer. You should always make a copy of the deleted sector housing the deleted files. There are many software programs that automate this process for you. If the data are in these parts of the hard drive, yet not visible to the operating system, there is a good chance you can undelete files you didn’t think could be recovered.


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