Arch Linux

detto

Member

Registered: 2006-01-23

Posts: 510

erasing my hdd

hey there!
i'm erasing a 200gb sata hdd atm by using this cmd

dd if=/dev/zero of=/dev/sda bs=64k

how long will that procedure take? is this bs= setting speedier than without? and if it'll take too long, can i abort it?
thx in advance! :-)

cheers,
deTTo

fk

Member

From: Germany

Registered: 2006-04-29

Posts: 524

Re: erasing my hdd

I use this with bs=1M, but I don't know the time

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Have you tried to turn it off and on again?

detto

Member

Registered: 2006-01-23

Posts: 510

Re: erasing my hdd

it just finished i GUESS

dd: /dev/sda: No space left on device.

that SEEMS correct, but is it? about 1 hour has passed.
thx 4 the quick response & in advance ;-D

cheers,
deTTo

zeus

Member

From: Korolev / Russia

Registered: 2006-09-19

Posts: 117

Website

Re: erasing my hdd

man shred

hightower

Member

Registered: 2006-04-02

Posts: 182

Re: erasing my hdd

If you want to have a _clean_ hard disk so that no one can restore the data, you have to use special programs or overwrite your disk several times.

200GB / 1h = 204800MB / 3600s = 56.9 MB/s

Yes, that SEEMS (:D) realistic

hightower

fk

Member

From: Germany

Registered: 2006-04-29

Posts: 524

Re: erasing my hdd

Why do you need special programs?

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Have you tried to turn it off and on again?

hightower

Member

Registered: 2006-04-02

Posts: 182

Re: erasing my hdd

Because the 1 or 0 information of one bit is stored in multiple (hundreds) of physical units. If you overwrite once only the majority of this units is set to the new state. So it is possible to recover the former state by analysing the unchanged units. In order to change these units, too, you have to overwrite again and again (I don't know how many times are sufficient).

The term "special" is misleading - these programs simply overwrite multiple times by default.

hightower

Last edited by hightower (2007-02-13 19:32:36)

Xilon

Member

Registered: 2007-01-01

Posts: 243

Re: erasing my hdd

How about

for i in `seq 1 10`; do
    dd if=/dev/zero of=/dev/sda bs=1M
    dd if=/dev/urandom of=/dev/sda bs=1M
done

That should wipe it fairly nicely. It would take around 20 hours or more though, and some data will still be there, you can never really wipe the disk clean