[Gllug] Disk Wipe

[Mike Brodbelt]

On Tue, 2004-05-25 at 12:28, Christian Smith wrote:

> >If your intention is to make the disk unreadable, that'll work.
> >Permanently....
>
> Not so sure these days.
> 
> The low level format legend is based on some control information being
> stored on early IDE disks. When you low level formatted, this control
> information was accidently wiped, rendering the drive useless.

I've always been under the impression that it has more to do with the
layout of tracks/sectors on the actual disk than any special control
data that gets lost. Software/BIOS utils that could perform a low-level
format invariably didn't know enough about the specific drive to do it
right, and so wrecked the drive. Really old disks weren't "smart" enough
for this to matter, and can be low-level formatted, but anything since
at least 1990 won't play ball. 

> These days, I'm guessing any modern IDE drive can be low level formatted.
> Afterall, how else would the drive be low level formatted in the first
> place?

Typically with software produced by the manufacturer, using information
unavailable to authors of low-level format programs.

> Hmm, almost tempting to buy a second hand drive to try it...

I've done it once, and that was about 10-12 years ago. The drives in
question was a 120Mb drive owned by a friend of mine, and had numerous
bad blocks, so we regarded it as too dodgy to put anything important on.
As we were curious, and had nothing to lose, we low-level formatted it
(with PC tools, I believe). After the low-level format completed, we
fdisked it and ran a DOS format, followed by testing the partition with
SpinRite. The DOS format took several hours to complete, and > 90% of
the disk turned into bad blocks. From memory, I think we got about a
10Mb usable partition from it - the rest of the drive was mapped out as
bad in the FAT. I've seen nothing since to lead me to believe that a
more recent drive would fare any better.

Mike.

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