----- Original Message -----

From: tmac

To: Bert Kiers

Cc: Nils Vogels ; toasters@mathworks.com

Sent: Tuesday, August 14, 2007 11:59 AM

Subject: Re: Disk content erase on a 740 running 6.2.2.

As I stated in the first reponse of this thread...

et yourself a disk_sanitization license (it is free!)
(once installed, you cannot remove)

Boot to the floppy menu. Use the menu to create a 2 disk root volume.
When finished, run through the setup.
Install your Disk_sanitization license then run the command:

disk sanitize start x.1 x.2 x.3 etc...

This will by default, write 3 patterns:
0x55
0xaa (the compliment of 0x55, 0x55 + 0xaa = 0xff)
0x3c (the 3 is three up and the c is three down, another nice off-setting bit pattern)

I believe it even starts off with a low-level format before the bit patterns.

When complete, I think the disks are move out of the spare pool so you
know what is done and what is not.

At this point, you would need to be the federal government, invest lots of money for specialized gear and spend lots of time to get data off the disks.

Why are those bit patterns important?

Disks are magnetic. They are nor absolute 1 or absolute 0. they "lean" towards 1 or "lean" towards 0. If the data has been on the drive long enough, the bits will have a tendancy to "lean a particular" way.

The bit pattern excersize will force the bits one way, then the other:
0x55 = 01010101
0xaa = 10101010
0x3c = 00111100

See the pattern now? These patterns try to reduce the amount of "leaning" going on.

If you want to be sure the data is gone without physical desruction, this is the best way to go. Of course, you can tell the command to use your own bit patterns and/or how many cycles to run.

--tmac

On 8/14/07, Bert Kiers <kiersb@xs4all.net> wrote:

On Mon, Aug 13, 2007 at 11:33:53PM +0200, Nils Vogels wrote:
> Hey Oskar!
>
> On 8/13/07, Oskar Pienkos <oskar_pienkos@sfu.ca> wrote:
> > Hello,
> >
> > I'm decommissioning my old 740 running Ontapp 6.2.2 and would like to
> > wipe the disk content.
> > Any ideas how can I do it?
>
> I'd boot into maintenance mode and choose to reinitialise disks and
> reinstall ONTAP. On ONTAP versions 7 that's menu choice 4.

How well does this erase the contents? Is it all overwritten? How often?
Or is it just a reformat of some kind that only rewrites the meta data?

What does 'disk zero spares' actually do?

One time, when I really needed to be sure the data was gone forever, I
reformatted the disks to 512 bps an ran wipe on them
( http://wipe.sourceforge.net/)

TIA,
--
Bert Kiers
XS4All UNIX systeembeheerder, suspected terrorist

--
--tmac

RedHat Certified Engineer #804006984323821

Principal Consultant, RABA Technologies
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