From
http://en.wikipedia.org/wiki/CompactFlash
"The even more advanced CompactFlash controllers will also move the data
that is rarely changed so that all blocks are worn evenly."
Also, reading
http://technet.microsoft.com/en-us/library/cc785914(WS.10).aspx says that
shadow copy on write is possible, so if your system is using that, the
storage medium is irrelevant, and the original contents will not be
overwritten. Some virtual machines also do delta / differential disk
writing, to preserve the original state.
Similarly, JPSoft's own CascadePoint could copy the original file, so
overwriting it will not destroy the contents.
My point is not to dispute whether or not it will work on your system, but
that there are things to be aware of if you have a need or obligation to
actually destroy the data. It might not be as easy as you think. There have
only been a couple instances when I had sensitive customer data that needed
to be destroyed, and those were done in front of the customer to their
satisfaction.
On Fri, Nov 12, 2010 at 08:02, Steve Fábián <>wrote:
> Jim Cook:
> | If it is important that you actually wipe the data, be sure that the
> medium
> | you are wiping writes data the way you think. I believe some compact
> flash
> | file system implementations, for example, always round-robin allocate a
> new
> | block when writing, thus extending the MTBF as much as possible. In that
> | case, overwriting to wipe does no good at all, until you fill the medium.
>
> Overwriting does not allocate new blocks, it updates the contents of
> previously allocated blocks. I seriously doubt any filesystem would write
> everything into a new block, and release the original block. Regardless, my
> personal interest is in standard hard drives using NTFS, so the issue is
> irrelevant, but thanks for the interesting information.
> --
> Steve
>
>
>
>
>
--
Jim Cook
2010 Sundays: 4/4, 6/6, 8/8, 10/10, 12/12 and 5/9, 9/5, 7/11, 11/7.
Next year they're Monday.
