On Feb 4, 2008, at 9:56 AM, Diehl, Gary (MVSSupport) wrote:
Ed,
I've been told the same thing. I worked SBLC for the AF, and we were
told that data could be recovered after up to 7 rewrites, and the
methodology was based on signal strength analysis. I.E. You read the
sector of a hard disk umpteen millions of times and get enough samples
of it to determine what was written there last time, overwritten once,
overwritten twice, etc, based on the signal degradation created by
overwrite.
Our destruction procedures were based on these assumptions. We had to
do massive overwrites and then physically take apart, scratch, and
then
bend old HDAs (3375/3380 drives) before they could go to DRMO for
metal
recycling. And the "new fangled" PC hard drives were degaussed, and
then melted in an incinerator for good measure.
I don't know how true the "recovery after x overwrites" is either, but
this is what we were trained on, and the paranoid procedures we
followed.
I'd be interested to see what methodology is used to ensure the
data is
really gone from IBM hard drives today, particularly with these
massive
RAIDs we all seem to use!
Gary Diehl
MVS Support
Gary,
A While ago someone on here indicated that the units you talk about
have some sort of built-in facility to just do that (erase the
data). I have no access to any documentation either. One could
argue just deleting the pointers should be good enough. I am a little
skeptical about this seeing as how the PC world doesn't to be really
interested in this issue. I have a feeling that the only good method
is to take the platters out and break them up or toss them in acid
and for safe measure a degausser.
I know the military is decent at doing decommissioning of drives. If
anything they are probably a little overkill which is fine with me.
Personally if they really wanted it GONE they should send it in a
rocket to the sun and let it vaporized already erased data. If
somehow agents were to land on the sun and intercept the rockets I
think they deserve to get it.
Ed
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