Destroying data permanently from old disks

[Martti Lautamaki]

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

[Pete Randall]

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

Pete

[James R. Ferguson]

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...

[Tom Geudens]

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

Regards,
Tom

[Bart Beeren]

By using dd you can "scratch the physical disks!
BB

[Donald Kok]

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

[Sanjay_6]

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

[James R. Ferguson]

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...

[Donald Kok]

Thanks James.

[Jeff Schussele]

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

[Cheryl Griffin]

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

Cheryl

[Frank Slootweg]

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.

[Robert R. Colp]

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

[Bill McNAMARA_1]

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

[Martin Johnson]

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

HTH
Marty

[Bill McNAMARA_1]

LOL !

[Martin Johnson]

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

[Volker Borowski]

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

[Bill McNAMARA_1]

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

Later,
Bill

[Martin Johnson]

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

Marty

[Diadina Cotte]

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

[Frank Slootweg]

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).