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Make Sure You Do This Before Donating or Disposing of Your Old Computer

How to Clear Your Computer’s Hard Drive of Personal Data

I know that some of us will be donating or disposing of our computers this year. I hope that each of you has considered that your personal information may be visible on your computer’s hard drive, even after you have deleted it. The data is actually still there and can be accessed by savvy computer users for malicious purposes.
eWaste on the curb

When you delete files, all you are really doing is telling your operating system to clear out its table of contents of those files. It doesn’t “zero out”, or “blank” the files as you might guess. You are essentially giving your OS permissions to write over the files you told it to delete. Since you deleted them, you told the OS you don’t need them, and therefore it can reclaim that space and report back to you the new “free space” size. In reality, all the data is still there and anybody with an undelete program downloaded from the Internet can recover some or even all of the data (including you photos, saved browser passwords, bank info, social security number, etc…) But don’t fret; you can still give away that computer safely.

Windows and Linux Users

Windows logo
To ensure that your data is wiped clean, use Darik’s Boot and Nuke. This is a free download that installs on a floppy or USB drive. Once installed, you can boot your computer to that floppy or USB drive and begin to wipe. Darik’s Boot and Nuke does an effective job of writing and overwriting the data multiple times with random 1s and 0s. This process will leave no recognizable files or folders left on the hard drive.

Mac Users

Disk Util Icon
Mac OS X 10.4 has a built in disk utility that can securely erase your hard drives. If you want to erase the System Disk, you will need to boot your OS X Install CD first. More info for Mac Users can be found here.

Do you know of any good data erasure tools?

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10 Responses to “Make Sure You Do This Before Donating or Disposing of Your Old Computer”

  1. Mark Antony says:

    A great post, poeple should take notice of this!

    The BBC did a programme about old Pc’s being picked up on rubbish dumps, with hard drives being taken out, shipped out to Nigeria and sold in shops over there! They contacted one person in UK and said they found out many things about them, work, family, CV, bank accounts, and all from the hard drive of a pc been scrapped!

  2. Maldiveslive says:

    Don’t just donate or dispose you computer with you love one photo in it.

  3. StampYourFoot says:

    When I threw away my old PC, i just made sure I took it apart and smashed up the hard drives. That was a fun afternoon.

  4. Allen23 says:

    wow I wish i would of know this before. But the only things on my computer back then where like neo pet files.

  5. Don says:

    I like to use the commercial program: Superscrubber for OS X. You can erase all, or just a section of your disks. It uses the US military certified method of zeroing. Unfortunately, the company, Jiiva has gone out of business!


  6. Right on!
    I’m guilty here too. My problem is I procrastinate wiping the hard drive, and the old computers sit in my office for a few years. By then even donation sites don’t want them because they’re too old.

    One thing I like about donating rather than recycling old computers (where possible) is for the tax benefits.

  7. I have to disagree with so called secure erasure of disks. Admittedly, it does wipe the disk but there are plenty of tools, both free and commercial, that can recover data. Your best bet is to remove the disk and reuse or smash it with Mr.Hammer – I love that part 🙂

  8. @Computer Discounts,
    Unless you are the NSA, I don’t think anybody is going to recover your data with a 7 pass erasure (even the NSA may not be able to recover data). Even a 3 pass erasure may be a bit overkill. I would certainly not want to dispose of my hard drive before I used one of these tools.

  9. Having worked for a number of organisations involved in security I have to say you’d be rather surprised what some of the readily available tools can do. That said, they’re not perfect but if you have anything personal on your hdd you can never be too careful. I suppose it comes down to personal preferences – I’ll need a fork lift to clear my backlog of disks! 🙂

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