Decommissioning an older server

[Peter Gillis]

Hi,

hpux 11.00 d390 and d220. Very soon i will be decommissioning these two machines. I am curious to know if there is a preferred method for ensuring that no data is (or bits of data) are left on the disks. If there is how do I go about doing it?

Thanks,
Maria

[Michael Steele_2 · Accepted solution]

To erase all sensitive data on a disk use:

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

I'd also use pvcreate and erase the VG header information.

But, as the link listed below will point out, some people get real uptight about this kind of thing:

http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x24b53a7b3682d611abdb0090277a778c,00.html

[Steven E. Protter]

When I take a system off the line, I do a complete operating system install, allocating all local disk.

This erases everything that was there and puts the system in good condition to show that it does work and support an OS.

At that point there is no possibility of anyone seeeing your old data, so long as you have physically disconnected from any disk arrays you are connected to.

You can now safely sell your machine in ebay. Or donate it to a charity like the Jewish United Fund.

SEP

[Michael Tully]

Hi Maria,

There are a few ways:

First remove the logical volumes and VG information by:

# vgexport /dev/myvg
# pvcreate -f /dev/rdsk/cxtydz

You could go to a further extreme and place a bunch of zeros on each disk, as per the link that was provided. It all depends on what is happening with the machine after. If your keeping it, and then using it as a test system, exporting the VG's will be sufficient.

Cheers
Michael

[Jeff Schussele]

Hi Maria,

Totally depends on *just* how sensitive the data is.

For absolute certainty, crush 'em & torch 'em.

For slightly less, overwrite 'em at the bit level >10 times with alternating 0s & 1s.

For even less, just all 0s

And on down the line....

Ask mgmt just how secure do they want to be? There IS an absolute $ value that can be assigned. That's something they can understand....

My 2 cents,
Jeff

[Peter Gillis]

Thanks for all the info, but just one more thing for the dummy - how can I prove that there us really only 1's, 0's or nothing on the disk. Just a a simple ll cmd or something like that?

Thanks everyone for all your help and patience.
Maria

[Balaji N]

hi,
as SEP suggested, the best way is to reinstall the OS. and re-create new VG's.

We keep such machines around for testing purposes. and some new system admin's are around, they install / crash / do whatever they want with these boxes.


-balaji

[Balaji N]

may be this of some help.
http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x624e28c64656d71190080090279cd0f9,00.html


and to see what is the actual data, use dd.


dd if= of=/tmp/file.out bs=512 count=1

and see the contents of the file.

-balaji

[Balaji N]

hi,
sorry for the follow up. since you are doing a low level write, u need to do a low level read to get the data.
-balaji

[Yogeeraj_1]

hi maria,

To erase all sensitive data on a disk use:

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

I'd also use pvcreate and erase the VG header information.

You can also write a layer of junk data on the disk to prevent any possibility of recovering data even from the physical level.

The following scripts does it. This shell script requires the cXtYdZ disk indentifier as an agruement. This script assumes /dev/zero exists.

#!/bin/sh
date
echo "Starting first pass now ..."
dd if=/dev/zero of=/dev/rdsk/$1 bs=8k
date
echo "33% done"
tr '\0' '\377' < /dev/zero | dd of=/dev/rdsk/$1 bs=8k
date
echo " 66% done"
dd if=/dev/zero of=/dev/rdsk/$1 bs=8k
echo "Wipe is complete."
date

hth
Yogeeraj

[Jeff Schussele]

Hi again,

You can't prove it......definitively.
I'm sorry, I didn't make myself clear earlier.
The point is entirely about scale.
The point about repitition is the key. Understand the physics of it and the distribution of reads/writes & the inherent properties of magnetic media & how that acts upon such.
Drift is a word that comes to my mind.
Doggedness is another....

Moral: If there's a platter they *may* get it. How much does one wish to spend....

My $0.02,
Jeff

[Peter Gillis]

Thanks again to all. flipping bits will do us , well mgmt, for now. I reckon though if they want 100% certainty no data on disk - smash the little ...things. That would even be fun!!

SEe yas.
Maria.

[Jeff Schussele]

Hear that!
Do us a favor & convince mgmt of that...it's true. THEN tell them you HAVE to witness it..just to verify!
We techies have to enjoy our little victories.
Sometimes the facts DO get in the way with businessmen's decisions.
Savor it when you can.

Cheers,
Jeff