Destroying data permanently from old disks (315 Views)
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Occasional Contributor
Posts: 5
Registered: ‎04-16-2002
Message 1 of 22 (315 Views)

Destroying data permanently from old disks

We have a leasing HP-UX server. We are changing disk system to new one.
Old box will be returned to HP.
If I only use rm or lvremove/vgremove commmands, how I can be sure that my company data will not be returned from disks?
What would be the most secure way to destroy old data?

Thanks
Outstanding Contributor
Posts: 16,205
Registered: ‎11-03-1996
Message 2 of 22 (315 Views)

Re: Destroying data permanently from old disks

How about running newfs or, for complete security, mediainit?

Pete

Pete
Acclaimed Contributor
Posts: 21,184
Registered: ‎07-06-2000
Message 3 of 22 (315 Views)

Re: Destroying data permanently from old disks

Hi:

Stopping short of an acid bath, this recent, lively discussion offers some other choices:

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

Regards!

...JRF...
Honored Contributor
Posts: 962
Registered: ‎11-23-2001
Message 4 of 22 (315 Views)

Re: Destroying data permanently from old disks

Hi,
pvremove will remove the LVM information on the disk ... but if you want to be completely sure, you can use "dd" ...

Regards,
Tom
A life ? Cool ! Where can I download one of those from ?
Advisor
Posts: 19
Registered: ‎07-08-2002
Message 5 of 22 (315 Views)

Re: Destroying data permanently from old disks

By using dd you can "scratch the physical disks!
BB
Life isn´t as simple as it seems
Respected Contributor
Posts: 473
Registered: ‎10-14-1998
Message 6 of 22 (315 Views)

Re: Destroying data permanently from old disks

There are unix-versions with /dev/zero, which delevers an endless stream of zero's. with that you can dd if=/dev/zero of=/dev/dsk/yourdisk.

If you have a device that is really empty, you could use this trick. Or maybe one of the forum members know how to implememnt /dev/zero?

Goodluck
Donald
My systems are 100% Murphy Compliant. Guaranteed!!!
Honored Contributor
Posts: 5,942
Registered: ‎04-15-2001
Message 7 of 22 (315 Views)

Re: Destroying data permanently from old disks

Hi,

To remove all the data from the disk, first remove the lv and then delete the VG's info from the disk and then do a dd to delete all possible data from the disk, say cxtydz

dd if=/dev/null of=/dev/rdsk/cxtydz bs=1024k

Hope this helps.

Regds
Acclaimed Contributor
Posts: 21,184
Registered: ‎07-06-2000
Message 8 of 22 (315 Views)

Re: Destroying data permanently from old disks

Hi Donald:

The thread I cited above...

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

...contains more information about '/dev/zero'. However, ff you are running 11.11 you should already have /dev/zero. If not, do this to create it:

# mknod /dev/zero c 3 0x000003 #...on 10.20
# mknod /dev/zero c 3 0x000004 #...on 11.x

# chown bin:bin /dev/zero
# chmod 666 /dev/zero

Regards!

...JRF...

Respected Contributor
Posts: 473
Registered: ‎10-14-1998
Message 9 of 22 (315 Views)

Re: Destroying data permanently from old disks

Thanks James.
My systems are 100% Murphy Compliant. Guaranteed!!!
Honored Contributor
Posts: 6,795
Registered: ‎02-18-2002
Message 10 of 22 (315 Views)

Re: Destroying data permanently from old disks

Hi Martti,

The *only* SURE way to completely remove data would be to crush & burn 'em.
Seriously, data has been retrieved from disks after up to 17 passes of random overwrites.
IF the pursuer is determined enough, it's only a matter of time & $ - they'll get it.

But normally 3-6 passes of random ones & zeros should be sufficient for most cases. IF you only overwrite w/zeros you may want to up that count some.

Rgds,
Jeff
PERSEVERANCE -- Remember, whatever does not kill you only makes you stronger!
Honored Contributor
Posts: 2,701
Registered: ‎05-11-2000
Message 11 of 22 (315 Views)

Re: Destroying data permanently from old disks

And where classifed information needs to be erased, you will want to use a wipe utility that is DoD Compliant.

Cheryl
"Downtime is a Crime."
Honored Contributor
Posts: 890
Registered: ‎09-06-2001
Message 12 of 22 (315 Views)

Re: Destroying data permanently from old disks

Adding to the other responses (and pointers given in those responses):

Do *not* use mediainit! mediainit *may* make the disk *less reliable*, but you won't *know* one way or the other.

The "Why?" is rather long. If you really want to know, search on "mediainit" and my name and you should find some pointers. If not, do the same search on Google Groups.
Advisor
Posts: 13
Registered: ‎02-02-1999
Message 13 of 22 (315 Views)

Re: Destroying data permanently from old disks

Martti-

You might consider checking the link:

http://www.lat.com

They have a program called unishread that might meet your requirements. I have not used this product, but based upon the write up on the site, it should serve your purposes.

We purchased a system with an external SCSI Hard Drive for classified information, then never used it!

Good luck.

Bob
Honored Contributor
Posts: 3,866
Registered: ‎11-14-2000
Message 14 of 22 (315 Views)

Re: Destroying data permanently from old disks

Well, speaking of burning the disks, you gotta make sure you do it well... I've heard a story where some building of a company in Finland caught fire, and up went the computer room.

Apparently they were so interested in just one disk, which was badly fire damaged (warped + melted) that they paid a small fortune to have the data restored... I guess they must have moved the heads manually.. in any case, moral is: be a real man, use a needle an magnet!

Later,
Bill
It works for me (tm)
Honored Contributor
Posts: 2,866
Registered: ‎05-07-2002
Message 15 of 22 (315 Views)

Re: Destroying data permanently from old disks

We use a portable degausser to erase old disks and tapes before they leave the company.

HTH
Marty
Honored Contributor
Posts: 3,866
Registered: ‎11-14-2000
Message 16 of 22 (315 Views)

Re: Destroying data permanently from old disks

LOL !
It works for me (tm)
Honored Contributor
Posts: 2,866
Registered: ‎05-07-2002
Message 17 of 22 (315 Views)

Re: Destroying data permanently from old disks

Bill,

It may be funny, but it is also scary. We have had operators bring down the wrong systems, use the wrong tapes for backups and type in the wrong year for a time changes. Scary stuff!

Marty
Honored Contributor
Posts: 1,521
Registered: ‎04-20-1998
Message 18 of 22 (315 Views)

Re: Destroying data permanently from old disks

This suggests to bolt a heavy 2 meters chain to the floor an tie the other end to the degausser, so it can only be moved in its designated area :-)
Volker
Honored Contributor
Posts: 3,866
Registered: ‎11-14-2000
Message 19 of 22 (315 Views)

Re: Destroying data permanently from old disks

I'd suggest tying it to the operator and sending him fishing...

Later,
Bill
It works for me (tm)
Honored Contributor
Posts: 2,866
Registered: ‎05-07-2002
Message 20 of 22 (315 Views)

Re: Destroying data permanently from old disks

Actually the degausser is no in the data center, but the warehouse. It is used prior to packing for shipment.

Marty
Advisor
Posts: 31
Registered: ‎05-29-2002
Message 21 of 22 (315 Views)

Re: Destroying data permanently from old disks

Consider doing a low level format or writing the drive with zeros.

As everybody said, data can still be retrieve, you need to repeat this operation a few times. Depending on the size of the drives, this procedure takes a lot of time.

Good Luck!

Diadina
Coffee please ;-)
Honored Contributor
Posts: 890
Registered: ‎09-06-2001
Message 22 of 22 (315 Views)

Re: Destroying data permanently from old disks

Do *not* use a (real) low-level format because that *may* make the disk *less reliable*, but you won't *know* one way or the other. See my reference to mediainit in my earlier response (mediainit tries to do a low-level format).
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