Wiping Multiple Hard-Drives with Shred?



I'm doing a kind of internship / jobshadowing thing with a small PC Shop to try and gain technical experience with the goal of getting into IT. One of the small starter projects the owner may let me tackle is erasing hard drives so they can be resold.

I am aware of Darik's Boot and Nuke, but wondered if there may be a simpler option by just using the Linux command Shred. I was thinking 3 passes of random data and 1 pass of zeros. I have wiped one of my own drives this way.

I'm curious about how this may work if I could hook up 3 or more drives at the same time. From the desktop environment, could I just simply open 3 terminals and run shred in each of them at the same time and be able to watch the progress? I'm also working on improving my knowledge of Hardware, so I thought I'd run this idea by other people before I put it into practice, but it seems like this could be a way for a Live Linux to bulk erase some drives. Even better if it's faster than DBAN so I can feel like I'm contributing to the store.

Just an FYI, some stupid admin I know managed to "DD" a hard drive. The data was however completely recoverable. (Thank goodness)

If you want to secure a hard drive from being harvested for data, do what Cyber Bunker does and literally shred the hard disks. (Again, I mean that literally)

If a data recovery service is good enough to recover a hard disk after being zeroed out, then there's a high chance your resold disks can be harvested as well.

If you still insist on selling the disks, you should write over it, wipe it, write over it, wipe it, repeat about ten dozen times, then sell it.

I expect people to disagree with my statement, but trust me, data can be extracted from a wiped disk even if you use elaborate software to clean it up.

On a side note, I've managed to extract data from my old Windows 95 machine. Not a zeroed drive, but I guess age is irrelevant as well. :)
Well, Shred can write random data to the disk with multiple passes. Would that help?
DBAN is a nice tool, and I think it does 6 passes. It looks like it has been bought out by a big company (Blancco) but is still available for free. Another Linux product that looks pretty good is KillDisk (http://www.killdisk.com/downloadfree.htm)

How is your boss on this issue? Some guys feel the extra security is worth the time it will take. Some guys will just do a quick format and think that is "good enough."
I believe he has already been using DBAN and I do think he wants something more thorough than a simple Format.

My impression is he is about doing a quality job and will not do anything half-assed.
I am happy to hear that. That is a good sign that he will be a good guy for you to work for and learn from.

You asked about wiping multiple drives at the same time. I don't know about DBAN's ability for that. The KillDisk program says in their FAQ (a new entry at the bottom) that they can wipe all fixed drives except the USB stick it boots from. That might help you, but I'm not sure about it. I haven't used this program before. But you're on your way... you will find which one suits your needs very soon. Good luck!
On http://www.marksanborn.net/howto/wiping-a-hard-drive-with-dd/:
To further complicate the recovering process we will write over the entire drive with random data.

dd if=/dev/urandom of=/dev/hda

This will write over drive ’hda’ with random data. Now the recovering process is hopeless.

If you are really paranoid or just want to be ultra secure you could write over the drive 7 times with random data. This is the same procedure the US Government uses to secure its own data.

for n in `seq 7`; do dd if=/dev/urandom of=/dev/sda bs=8b conv=notrunc; done
# chmod a+x wipeIt
sh wipeIt`
Notrunc means ‘do not truncate the output file’.
Regardless of which software you use, writing random data all over the disk will do the job. I wouldn't go much further than 2 passes for that purpose.

Doing the math, I'd say 1 pass is enough wipe for common use. The odds the average joe will even try and only then maybe recover any relevant data from such storage are extremely low, near zero.

After writing random data on the whole disk a single time, a recovered video/pic (if its index and or header are sort of readable) will be so distorted that it will be harmless, for instance. As to text, I wouldn't mind at all, **it would be unreadable.

P.S.: as to cleaning multiple hard drives, you could random dd all of them at once on multiple terminals. Or try writing a piece of software that handles multiple dd instances. Just make sure to set BS to 1-8bit and be happy with a really safe single step wipe (although time consuming).
Last edited:

Members online