Re: Wiping hard drives

[Martin Steigerwald <Martin@lichtvoll.de>]

Am Mittwoch, 14. September 2011 schrieb yudi v:
> > I used an external USB/eSATA case hooked up via eSATA and then bootet
> > GRML. The BIOS did not protect the external drive and I was able to
> > transfer the ATA Secure Command via eSATA. I bet it might not work
> > via USB tough.
> > 
> > Booted from ubuntu live USB, checked if the internal disk was frozen,
> > yes.
> 
> Suspended the system and back on again, not frozen. This hack was
> mentioned in http://ata.wiki.kernel.org/index.php/ATA_Secure_Erase
> 
> > Tough my SSD also reports SECURITY ERASE UNIT, does your HDD have
> > that too?
> > 
> > merkaba:~> hdparm -I /dev/sda | grep -i erase
> > 
> >                supported: enhanced erase
> >        
> >        2min for SECURITY ERASE UNIT. 2min for ENHANCED SECURITY ERASE
> > 
> > UNIT.
> 
> yes. what exactly does Security erase unit mean?
> 
>  supported
>         not     enabled
>         not     locked
>         not     frozen
>         not     expired: security count
>                 supported: enhanced erase
>         132min for SECURITY ERASE UNIT. 132min for ENHANCED SECURITY
> ERASE UNIT.

I think it is the ATA Security Erase I wrote about. Tough it seems it may 
refer to different ways of doing the erase.

Given from the time difference, I think, that the Intel SSD 320 security 
erases itself by deleting the crypto key, and that your harddisk might do 
it by overwriting its data. Cause when your harddisk used encryption and 
just overwrote the crypto key, then it should be able to security erase 
quicker than in 132 minutes. And if the Intel SSD overwrote all of its 
data to security erase itself it would need longer.

-- 
Martin 'Helios' Steigerwald - http://www.Lichtvoll.de
GPG: 03B0 0D6C 0040 0710 4AFA  B82F 991B EAAC A599 84C7