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Shubhangi Yadav
Asked: 2012-04-22 06:43:50 +0800 CST

Permanently erasing external hard disk data

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I have a seagate hard disk which is under warranty for next 4 years. I always had a problem reading this hard disk as I had to tilt the usb cable for it to make proper contact with the pins. However, for last 2 to 3 months, it has stopped working altogether.

fdisk -l does not yield any device info apart from the partitions on the internal hard disk. However, the hard disk does light up when I successfully connect it (that is, by tilting the USB cable)

My problem is that I can not simply give my hard disk to the seagate customer support for replacement as there are some personal pictures and scanned images of almost all identity cards possible and educational certificates.

Is there a way to somehow erase the data on this hard disk without opening it (as that would void the warranty)? Magnetic degaussing comes to mind, however, as this guy has mentioned here, it requires industry grade magnets to do it. I know I should have encrypted my data and I learned it the hard way, but is there a way out so that I can erase the data and make use of the warranty as well?

hard-drive data-loss

4 Answers

  1. We have answered this fully over on security stack exchange - https://security.stackexchange.com/questions/6133/best-method-of-retiring-hard-drives - and it was such a popular topic it also got a feature on our blog - http://security.blogoverflow.com/2012/02/qotw-18-how-can-we-destroy-data-on-a-hard-drive/

    Summary of key methods

    • Degaussing
    • Physical Destruction
    • Manual Dis-assembly
    • Electrical Scrambling
    • Wanton Destruction
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  2. Now be careful that you use the exact right device, or you will be erasing the wrong disk.

    1. Find the device name to your USB drive: cat /proc/partitions. It is probably /dev/sdb, but you should check the size against the actual disk size. If in doubt, copy the output in your question. You can double check with the dmesg command. That should show the connecting/disconnecting of the USB cable and the exact device name assigned.
    2. sudo bs=4M if=/dev/zero of=/dev/your_device_name
    3. The drive LED will light up and you'll have to wait a while until it finishes. Approx. 50-100 GB/hr. In your case you might want to use an elastic band to keep the USB connector up.

    You can repeat it several times, but that is not really necessary. Recovering data from a drive erased this way is already extremely difficult. You'll need a specialized laboratory and drive firmware already.

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  3. If your disk is not working anymore degaussing seems to be the only way. There are some professional degaussing services around. Look for one close to your location. Here the first one I found on google ... http://www.garner-products.com/Degserv.htm

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  4. If you are that paranoid that you do not trust the drive manufacturer to look at your data, then you simply need to destroy the drive physically, write off the cost, and buy a new one rather than return it for repair or replacement.

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