[Novalug] Hardqare (?) Question : Wipe Geekstick?

The Doctor drwho@virtadpt.net
Wed Dec 17 09:22:19 EST 2008


ethan@757.org wrote:
> Look, wiping the memory stick once isn't going to do anything to the life 
> span of the thing. If you write a file to it ten times, and then wipe it 
> once, that is 11 writes on media that is good for lots. Flash has 

I've read a few whitepapers that said that each storage cell in a given
flash memory module are good for something like a half-million writes
each, give or take a few thousand.  When you factor in wear leveling,
they can take a lot of abuse before sectors start going bad.

> improved. I've seen CF cards get bad blocks, but that was a 10 year old 
> card+. People are using thumbdrives heavily every day, I use my digital 
> camera card like crazy... No problems.

The oldest one I have is eight years old, and it's still going strong.

> Also, you only need to "zero out" a drive once... hard drive or flash. All 
> the "8 pass wipe" stuff is BS. The rumors of gov't analyzing disks that 
> have been wiped 6 times is bunk AFAIK.

The seven pattern wiping method described in 5220.22-M is used for
magnetic media, probably more out of paranoia than anything else ("We
know what we're capable of but we don't really trust what we know about
what They're capable of, so let's be safe.")  Even Gutmann said that the
methods described in his paper were for antiquated drive technologies
and didn't really apply to anything used today.  Flash media's more
tricky due to redundant storage cells and wear leveling algorithms built
into the on-board microcontroller.  When sanitizing a flash module it's
hard to be sure that you overwrote every data cell that held any
sensitive data.

For what it's worth, DoD 5220.22-M specifies that a given flash storage
device should be wiped using the process in the chip manufacturer's data
sheets if it's to be re-used.  It also says that flash storage is to be
overwritten, wiped with the manufacturer's method, and then physically
destroyed if the storage units are being taken out of service.  I've
seen ten pound sledgehammers used for the final step of that particular
process.

-- 

The Doctor [412/724/301/703]

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WWW: http://drwho.virtadpt.net/

The first cup of coffee recapitulates phylogeny.


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