File/Disk Erasing for computer Disposal and/or Transfer


Securing your data

Most departments will either transfer or dispose of their old computers when they purchase new systems.  You will want to protect your documents with sensitive information from being exposed to others that may end up with your old system.  If you think that by deleting your files or reformatting your hard drive will be good enough then you should probably read the rest of this document.

What is the difference between erase and delete?

When you delete a file on a computer it is not actually removed from your hard drive.  The system just removes the record of the file’s existence from the part of the system that keeps track of where all of your files are located.  Think of it this way, you have a piece of paper that you wrote your name, address, phone number on and you decide to throw it in the trash can.  Is the information you wrote still on the paper?  When you empty the trash can and the garbage is dumped in a land-fill, is the information still on the paper?  Of course it is, just because you don't have access to it doesn’t mean that the information can’t be picked out of the trash and used by someone else.

Now think of erase as a more permanent way of disposing your information.  It's similar to using a paper shredder or burning the paper.  It makes it a lot harder for someone to retrieve the information.  In a computer, eraser programs will write 1s and 0s over the file that you are trying to remove.  It will usually do this several times to make sure that the information is “shredded” from the hard drive.  Note that it is still possible to recover information after a single pass of erasing.

Well I formatted my hard drive so my data is destroyed right?

WRONG! Formatting your hard drive is similar to the delete command. It does not actually remove data from your hard drive. All formatting does is create a new file record table to keep track of the files you place on after the format is done.  This is the same for the FDISK utility. You can still retrieve the data until you actually write new files over the old data on the hard drive.

Are there other ways of removing my data?

Yes, the first 2 options will destroy the hard drives (but it will be a permanent way of removing access to information on the hard drive). The 3rd option is a recommended way to erase the data and still use the computer.

1)                  Physically destroying the drive. This is a good choice when your hard drive has failed, “crashed”. Remember that even though you can’t use the hard drive it still holds the information you put on it.  Hard drive’s can be disassembled and data can still be retrieved from the drive platters.  

2)                  Degaussing the hard drive.  Degaussing will demagnetize the fields used to store data on the hard drive.  Usually when this method is used the magnetic field is so strong that the hard drive is damaged beyond use.

 3)                It’s best to use an eraser program so others can still benefit by being able to use the computer.  Please review “Securely Deleting Electronic Information” for information on programs and procedures for erasing your files.  This document also has information on other electronic storage and devices that you may want to erase before disposal.

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Article ID: 672
Created: Fri, 01 Dec 2006 9:13am
Modified: Tue, 06 May 2008 3:23pm