Re: How to erase all data on disks

On 3/3/08, Leinweber, James <[email protected]> wrote:
> > I have a Compaq Proliant ML370 server running Red Hat Linux release
>
> > 7.1. The server has two local disks each 18GB and mirrored as RAID 1.
>  >
>  > How do I erase all the data on each disk?
>
>
> As a theoretical matter, it's pretty hard, particularly against really
>  well funded adversaries such as the NSA, who might have scanning
>  electron microscopes and be able to read remnant magnetism.  As a
>  practical matter, it's sufficient to:
>
>  A. Boot a rescue disk
>  B. Run "dd if=/dev/zero of=/dev/sda & dd if=/dev/zero of=/dev/sdb"
>
>  This is the essence of what the dban suggestion was.  It won't take
>  care of stuff like data in sectors that were remapped as bad, but it
>  will be good enough for compliance with most regulations such as
>  HIPAA or FERPA or whatever.


If you have a few days to turn the drives over to the receiving party
you can use a loop:

  while true
  do
    dd if=/dev/zero of=/dev/sdy
    dd if=/dev/zero of=/dev/sdz
    dd if=/dev/urandom of=/dev/sdy
    dd if=/dev/urandom of=/dev/sdz
  done

Just let it run for a day or two.

If it's a boot disk you're wiping make sure you're booted off a CD
first.  If you can get two shells going you can make that two loops,
one for each drive.

I can't speak to different security requirements (HIPAA, NSA, etc),
but this will do a lot more than just zeroing out the drive.

I don't recommend doing this for SAN attached devices, it might affect
the performance of other systems using the SAN.

-Gene
[email protected]


>
>  -- Jim Leinweber
>  State Laboratory of Hygiene, University of Wisconsin - Madison
>  <jiml-qDHGe9P1N6L2fBVCVOL8/[email protected]>

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