topic Re: disk wiping issues in Operating System - HP-UX

disk wiping issues

Gregory Hartmann — Fri, 22 Jun 2001 15:55:25 GMT

I wrote an Xwindow program that uses the UNIX command "dd if=file of=/dev/rdsk/c0txd0 bs=1024k", where x=1 for the system disk, x=2 for the archive disk, and "file" contains all 1's, all 0's, or alternating 1's and 0's (depending on the pass the program is on) The program does 7 passes, writing all 1's, then all zeros, and repeating this 2 more times, with a final pass of alternating 1's and 0's. Each pass consists of 4096 calls to the dd command, since we are using 4Gb disks. This works fine on the archive disk, but when I try and run it on itself (the system disk) it appears to be working ok but when I do a "xd" on the disk it appears that there is still alot of garbage still on the disk. I would greatly appreciate it if anybody could tell me what is going on and what, if anything can be done to fix this problem, or if there are better ways to do what I'm trying to accomplish.

Greg

Re: disk wiping issues

Jim Turner — Fri, 22 Jun 2001 16:00:05 GMT

Is there any reason why a simple mediainit won't work for you? Are we talking spook stuff here?

I used to work for an "Agency" whose idea of "wiping a disk" consisted of melting down the platters. And that was after the oxide coating was removed from the platters with an acid bath. Talk about overkill :-)

Re: disk wiping issues

Bill McNAMARA_1 — Fri, 22 Jun 2001 16:02:13 GMT

the system disk has active/open files on it.
including the dd command and the /dev/dsk device file.

Blank the disk from support media memory based filesystems..

Bill

Re: disk wiping issues

Gregory Hartmann — Fri, 22 Jun 2001 16:07:58 GMT

Yes, wer'e talking spook stuff here. The security regulations at the air force base here
(Vandenberg) require a series of 1's and 0's be written to the disk 6 times with a final pass of alternating 1's and zero's in order to remove all possibilities of classified data. The only other alternative is to physically destroy the disk(s), which my managers tell me they want to avoid doing if at all possible.

Re: disk wiping issues

Patrick Wallek — Fri, 22 Jun 2001 16:21:54 GMT

You won't be able to run this on the system disk.

The way I think I would do it is this:

1) Run said script on all disks except the OS disk (vg00). Hopefuly the OS is all on one disk.
2) Reinstall a BASE HP-UX OS onto one of the disks that has been wiped.. Don't enable networking or anything else, just install the OS.
3) Boot from the new OS disk.
4) Run your script now agains the OLD OS / boot disk.
5) Now all you have is a system with a base HP OS, with no networking or anything else enabled.

Re: disk wiping issues

Paula J Frazer-Campbell — Fri, 22 Jun 2001 16:48:35 GMT

Hi

Write your clean up file to CD, Tape or Floppy.

Boot from CD and the fire up your file from whichever media you placed it on.

Just and idea.

Paula

Re: disk wiping issues

Gregory Hartmann — Fri, 22 Jun 2001 17:08:27 GMT

Thanks all for the help. Is it possible to make a boot floppy (ala DOS) for HP-UX on which I can run my program. If so, how would I do it?

Re: disk wiping issues

Gregory Hartmann — Fri, 22 Jun 2001 17:32:26 GMT

Bill,
I'm pretty much a newbie at UNIX, Could you explain what you mean by "Blank the disk from support media memory based filesystems" Is it
possible to run everything in memory so as to not tie up the disk?

Re: disk wiping issues

Paula J Frazer-Campbell — Fri, 22 Jun 2001 17:40:29 GMT

Hi

If you boot your machine from the support media (CD) then you will not be using the on board disks as Bill has said.

Now if you have your clean up routine on a disk (floppy) you can run it against ALL disks on your system.

Paula

Re: disk wiping issues

Paula J Frazer-Campbell — Fri, 22 Jun 2001 17:48:25 GMT

Hi

Booting from core/install CD:-

Power on server, and interrupt boot when You see it on console.

Search for CD path with sea command
>sea

Also note floppy path.

boot from CD with

bo

E.G
> boot 0/0/1/0.1
Interact with IPL (Y, N, or Cancel)?> n

HTH
Paula

Re: disk wiping issues

Brandilyn Carpenter — Wed, 13 Mar 2002 16:11:45 GMT

I am in a similar predicament to yourself. I was wondering how you created your "input" file.