[CentOS] Utility to zero unused blocks on disk

[Valeri Galtsev]

On Mon, February 8, 2016 5:45 pm, John R Pierce wrote:
> On 2/8/2016 3:33 PM, Valeri Galtsev wrote:
>> DRAM had more persistent imprint of information that was sitting in it,
>> which appears much harder to destroy than information on hard drive.
>
> well aware of that.   30 years ago a friend and I built a specialized
> video card for a consulting project....   discovered on the prototype
> that we could power it down, go home, come back the next day, and power
> it up, and sufficient image remained in the DRAM to be totally
> recognizable.   sure, it had 'noise' bits all over it, but whatever was
> on the screen the day before was still visible.
>

This is amazing! That is what distinguishes experts from us mortals: what
we just learned by reading they saw themselves (sometimes quite a while
ago)! On the other hand, why I'm so surprised? This is why they can answer
any of our questions on this list in a split second.

Still, I'm very impressed!

Valeri

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