topic Re: Clean disk ? in Operating System - HP-UX

Clean disk ?

kate32 — Tue, 22 May 2007 14:57:37 GMT

Hi,
I have been asked to clean data from the disks (rp7424 internal disk HP) HP-UX 11.0 because there were borrowed by hp and contains data.
Do you have any idea how to do it ?

Thanks in advance.
Cheers
Kate

Re: Clean disk ?

James R. Ferguson — Tue, 22 May 2007 15:02:38 GMT

Kate:

A very large magnet and a bath of aqua regia works quite well.

If you are REALLY intent on reading what was once there, the acid-bath is about the only sure way to prevent this.

It *is* possible to read data written 10-15 (or more) passes ago with the proper technology.

A simple solution is to write zeros or some random pattern at least once over the disk. This is a "reasonable" attempt for most.

# dd if=/dev/zeros of=/dev/rdsk/cXtYdZ bs=1024k

or:

# dd if=/dev/urandom of=dev/rdsk/CxtYdZ bs=1024k

Note the use of the raw disk device to circumvent the LVM layer. Note, too, the use of a large blocksize for fast I/O.

Regards!

...JRF...

Re: Clean disk ?

Ivan Ferreira — Tue, 22 May 2007 15:03:21 GMT

Hello, please see:

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=1024405

Re: Clean disk ?

A. Clay Stephenson — Tue, 22 May 2007 15:03:31 GMT

For all but the most rigorous needs, this will suffice:

dd if=/dev/zero bs=64k of=/dev/rdsk/cXtYdZ

If you are doing system disks, do them last.

Re: Clean disk ?

Bill Hassell — Tue, 22 May 2007 15:05:25 GMT

The simplest is to boot up into single user mode, determine the physical disk device file(s) and then run mediainit on each one. Leave the root disk to the last. When mediainit is finished with the last disk, the system will probably panic as there is nothing on the disk anymore. For high security situations (military, government, etc), the best solution is a sledge hammer.

Re: Clean disk ?

Geoff Wild — Tue, 22 May 2007 15:13:21 GMT

Easy way:

pvcreate -f DISK

then create a vg and add the disks to it.

next, create a lvol - using all the space.

next, newfs that lvol...

Then, remove the lvol, and vgexport the vg

No more relevant data at all :)

Rgds...Geoff

Re: Clean disk ?

James R. Ferguson — Tue, 22 May 2007 15:25:53 GMT

Kate:

Please also see:

https://forums1.itrc.hp.com/service/forums/helptips.do?#28

...JRF...

Re: Clean disk ?

Sandman! — Tue, 22 May 2007 16:23:50 GMT

We recently purchased disk scrubbing services from HP. Check out the URL if interested (although it ain't free unlike the other solutions).

http://h20219.www2.hp.com/services/cache/66370-0-0-225-121.aspx?jumpid=reg_R1002_USEN

Re: Clean disk ?

kate32 — Tue, 22 May 2007 18:42:57 GMT

Hi guys,
cheers for your reply.

I will follow them and for the first time be able to crashed everything and have some fun! yeap will be funny!

Thanks again.
Cheers
Kate

Re: Clean disk ?

Rasheed Tamton — Wed, 23 May 2007 03:18:47 GMT

Hi,

dd is the easy way. Mediainit also goo one. Damaging/destroying/degaussing disks are other ways around. But you are returning back the disks to HP!!!

Here is the commercial one:
BCWipe for UNIX is designed to securely delete files from the disk. Standard file deletion leaves the contents of the "deleted" file on your disk. Unless it has been overwritten by files subsequently saved, it can be easily recovered using standard disk utilities. BCWipe is fully integrated into the Windows Shell and efficiently shreds data in files so that they can not be recovered by any means.
http://www.jetico.com/bcwipe_unix.htm

Regards,
Rasheed Tamton.