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Name: Stuart
Status: Other
Age: 40
Location: N/A
Country: N/A
Date: Around 1999


Question:
When you delete a file from your computer e.g., a word document, where does the actual data go?



Replies:
When you delete a file, the data actually stays on the drive. The files are just renamed and marked as deleted. On a Windows95/98 or Macintosh, they are renamed and moved to a special folder for deleted files. The data doesn't actually change, the computer just changes the name so the file appears as deleted in the new folder.

Then, when the file is emptied out of the recycle bin or trash can, the file name is changed again so that can be overwritten by new data, but the data remains on the drive.

Because just the names of the files are changed, programs like Norton can "recover" deleted files, as long as the space the file occupied before it was deleted hasn't been used by a new file.

I hope this answers your question.

Thanks,
--ET


Usually, it doesn't go anywhere. In most computer operating systems, a deleted file just has a character changed in its name (or some related identifying tag), so that the computer knows not to bring it up when asked to list its files. When the computer needs disk space later, say, if you want to save a new file, it can write the new data over the old data that has been marked "free." But it won't actually erase the old data until then.

This is how programs such as Norton Utilities can recover deleted files. The longer a file has been deleted, the less the chance of recovering it, because chances are parts of it have been overwritten by newer files.

This is also part of the computer security scandal that has hit America's National Laboratories recently. If a secret computer file is loaded onto an unsecure computer and then deleted, much of the data will still be on the disk, and it can be recovered by some programs.

Richard Barrans Jr., Ph.D.


Stuart, that is a good question.

The file does not go anywhere. But the "Pointer" in the File Allocation Table changes and marks that physical space on the disk as empty, or able for storage. In reality, you are most likely writing over the old file or parts of it when you make a new file and save it on your hard drive.

Joe Noga
DEP Network Support


The disk contains a "file system", which is a method of storing the data on it. Very rarely is a file stored as one continuous strip of magnetized disk material. You can see that trying to do so would never work if you were all the time storing files of various lengths, and continuously erasing them, modifying their lengths, writing new ones, etc. Instead data is stored in small, fixed-size chunks, blocks, and at the front of the disk there is a table of contents which lists, for each file, which blocks and in which order constitute the contents of the file.

When the computer "erases" a file it merely notes in the table of contents that the blocks formally assigned to file such-and-such are now free to be reassigned to another file. Only when they are in fact reassigned, and only when the new file actually overwrites them with new data, does the original data disappear.

Dr. Grayce



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