[CentOS] Utility to zero unused blocks on disk

Mon Feb 8 23:45:32 UTC 2016
John R Pierce <pierce at hogranch.com>

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.

john r pierce, recycling bits in santa cruz