QuickCheck: Is something deleted from your computer gone forever?

WHEN you place a file in a computer's recycle bin and clear it, it is gone forever and you will never get it back.

Is this true?

Verdict:

FALSE

Deleting a file from your computer does not mean that it's gone forever, in fact it is fairly easy to recover a deleted file.

To understand why, you have to understand a little about how computers store information on your hard disk or in the case of mobile phones (and newer computers) solid state drives.

When a computer copies or writes a file to disk, it allocates the space required for it on your storage drive and 'remembers' that it's put something there.

Depending on the size of the file, the data could be written in the same area on the drive or spread out across the disk wherever there's space.

The important part is that the computer 'remembers' that the data is there so it does not overwrite it.

When you delete a file, your device will not wipe off the disk, instead it will untag the space that it's on so that the next time it needs to write a new file it will use the freed up space to do so.

This means that the original data is still there until it is overwritten.

There are tools that are freely available online that can scan drives for deleted files and recover them.

If the file was only just deleted, then these tools will more likely than not be able to recover most if not all of it.

The only way to securely delete a file is to overwrite the sector of the disk it's on so that the older data is removed.

Again, there are tools available online that can help you with that. These tools will either over-write the area of the disk where the targeted file is with either ones, zeroes or random ones and zeroes before tagging the area as free space.

Again forensic tools (like what the police might use) can still recover files deleted this way.

With older drives (drives that were made in the 90s and older) you might have to wipe the area several times in order to delete so that these forensic tools would not be able to recover them.

Newer hard disks however do not have this problem so a single wipe usually is enough, two or three in you are paranoid.

As a side note, secure deleting of files really only works on the platter type hard disk drives, newer solid state drives cannot be wiped with any degree of confidence because of the way it stores and uses the data.

In that scenario, it might be best to make sure your data is encrypted when it is written so that the files would be gibberish even if it were recovered, but that is a story for another day.

References:

1. http://www.datarecoveryspecialists.co.uk/blog/how-is-data-in-a-computer-stored

2. https://www.ibm.com/topics/data-storage

3. http://www.datarecoveryspecialists.co.uk/blog/how-is-data-in-a-computer-stored

4. https://safecomputing.umich.edu/protect-yourself/prepare-devices-disposal/securely-delete-files