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Learn how to erase your hard drive before you sell or donate it.

Posted By : of Data Doctors on October 30, 2003

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I have an old hard drive and want to get rid of it, but I want to erase my info on it first, before I donate or sell it. How do I do this?

- Charlotte

This question was answered on October 30, 2003. Much of the information contained herein may have changed since posting.


Removing personal data from a hard drive before the sale or donation of a computer is vitally important, since you have no control of it once the drive leaves your hands.

Because of our years of experience in the data recovery business, I was asked to help in a television news story where we purchased used hard drives from various companies and examined them to see if we could ‘retrieve’ critical data from them.

The intent was for us to use basic data recovery techniques to see what could be derived from these random drives, but to our surprise, we didn’t have to do anything to get the data, because it had never been removed in the first place.

The data that resided on these drives where actually court records from computers that had been leased by a municipality

It turned out that the municipality thought that the leasing company was going to remove the data and the leasing company assumed that the municipality had removed it.

The leasing company sold the equipment at an auction and the hard drives ended up on a used computer company’s store shelves, complete with all the data intact.

There are a number of things that can be done to protect your personal information on old hard drives.

The first is to remove the hard drive from inside the computer and donate or sell the computer without the drive You can store the drive as a tertiary backup of old data or destroy the drive (take it apart, use if for target practice in the desert, etc.).

Many feel that reformatting and reloading the operating system will securely remove the data, but our company routinely retrieves data from drives that have been accidentally reformatted, so it isn’t really very secure.

An easier way to assure that your data is scrubbed clean from the magnetic platters of the drive is to install a program that uses a sophisticated overwriting scheme to ensure that data is irretrievable

For Windows users, I have long recommended a free program called Eraser, which is available at www.tolvanen.com/eraser This simple program installs into the operating system and becomes on option whenever you right click on any file.

The ‘Erase’ option that will appear in the dialog box will open the program and ask for your confirmation to remove the file and overwrite it 35 times.

The standard delete function in Windows actually only removes the first character of the filename, but the file remains in tact, magnetically Eraser will actually scrub the file from your hard drive and will not send it to the Recycle Bin.

Eraser also allows you to securely remove a file, a folder, subfolders or scrub the empty space on your hard drive clean (since the empty space contains the file fragments of your previously deleted data)

Mac OS X users can download a free utility from www.download.com called SafeShred and older Mac OS users can try Shredit from www.mireth.com to accomplish the same task.

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of Data Doctors on October 30, 2003

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