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