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Re: What is the universal (world wide) understanding behind degaussing harddisks?




On Mon, Apr 02, 2018 at 09:40:40PM +0800, Turritopsis Dohrnii Teo En Ming wrote:
> Good evening from Singapore!
> 
> The foremost question which I want to ask is, what is the universal
> (world wide) understanding behind degaussing hard drives?
> 
[Snip long and entertaining problem description]
> 
> Please advise.
> 
My preference is to first thoroughly shred the device (for traditional
spinning disk, as these utilities are not especially effective on solid
state media thanks to write leveling):

sudo shred -n 37 -v -z /dev/sda
(or alternatively, boot a DBAN disk and use its wipe function)

Then, if it has ATA secure erase (hdparm -I /dev/sda | grep -i erase), I
also wipe it like so:

hdparm --security-set-pass password /dev/sda
hdparm --security-erase-enhanced password /dev/sda

It is necessary to first set the password, assuming it has not
previously been set, or the drive will just return an error.

Also, the ATA enhanced erase is, as far as I know, the best option for
wiping an SSD. Assuming, that is, that you do not want to physically
shred/pulverize the device.

As an interesting note, the enhanced erase takes on the order of ~3
*hours* for a decent sized (e.g., 2 TB) HDD, but on the order of ~3
*minutes* for an SSD of the same size.

Regards,

-Roberto

-- 
Roberto C. Sánchez