Floppy recovery

[Jerome H. Fine]

 >ethan at 757.org wrote:

> If a disk has all zeros written to it, as far as I know from what I've 
> read there is no hope of recovering the data. There were rumors that 
> the government could do it based on really fine detection of magnetic 
> levels or something -- but it was rumor. There are bounties out there 
> if anyone can pull it off.
>
> I understand data can be recovered when the file entry is removed from 
> an allocation table but data has not been zereod/randomly written over.
>
> tl;dr: single pass is fine -- no need to triple pass erase.

Since this thread has been focused on Floppy media, my assumption
is that writing all zeros does not refer to a hard disk drive.  Is my
assumption incorrect?

I have a (exactly!!) one GB file with all zeros (obviously not a floppy)
on my hard drive.  If I fill the remaining storage with copies of this
file, does that eliminate recovery from that portion of the hard drive?

And since I have two physical hard drives, copying from a one GB
file from one physical drive to the other physical drive usually
takes only about one minute, so it would be quite an efficient
method to destroy any old data.

Jerome Fine