[CentOS] Utility to zero unused blocks on disk

[Valeri Galtsev]

On Mon, February 8, 2016 4:22 pm, John R Pierce wrote:
> On 2/8/2016 2:14 PM, Chris Murphy wrote:
>> DBAN is obsolete. NIST 800-88 for some time now says to use secure erase
>> or
>> enhanced security erase or crypto erase if supported.
>>
>> Other options do not erase data in remapped sectors.
>
> the only truly safe way to destroy data on magnetic media is to grind
> the media up into filings or melt it down in a furnace.

Without any intent to contradict... This article I found to be very
instructive reading:

https://www.cs.auckland.ac.nz/~pgut001/pubs/secure_del.html

As far as hard drives are concerned, it changed my mind about magnetic
media (hard drives): from "you never will be able to securely destroy
data" to "one pass of writing zeroes is sufficient for modern drives.
Bringing platters over 1000 times deep into hysteresis back and forth is
enough to destroy even residual magnetization related to magnetic domain
aging... On modern drives though... No, I decided to not spoil it for
those who decides to read that article. One thing I learned from there:
DRAM had more persistent imprint of information that was sitting in it,
which appears much harder to destroy than information on hard drive. I
hope I intrigued you enough to go and read that article.

Valeri


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Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247
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