10 Mar
2011
10 Mar
'11
5:41 a.m.
Message: 17
Date: Wed, 9 Mar 2011 15:05:30 -0500
From: Joachim Thiemann <joachim.thiemann at gmail.com>
Subject: Re: Who will be the last HD maker down the road?
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Message-ID:
<AANLkTinuT62O+YRh=V9h3Ad9zEjGwN_W4z-kvTjSRj+B at mail.gmail.com>
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Writing a '0' to a location of the flash that used to be '1' MIGHT
leave the internal analogue state at a higher level than if the bit
previously was '0'. If you then operate the flash in abnormal
conditions (messing with the supply voltages) you MAY be able to get
the memory into a state where the reading thresholds are "just right"
to get the old state.
That only gets you so much. If I copy a stream from /dev/urandom to the
card having an occasional bit recoverable isn't going to help because of
all the bits that can't be recovered. From what I have read I am alot more
confident flash can be safely erased with software than I am about a
physical drive since magnetism is harder to clean out than flash. Seems to
me the point is not relying on a filesystem delete operation but actually
filling the drive with random data. And as I said destroying flash is alot
easier than smashing a hard drive.