If the device is or closely emulates SCSI control, there are options in
the format low level command which (if implemented) can get a drive to
ignore its bad sector maps, starting over. If cleaning a disk, then, using
these commands after a normal pass should give the most access to any
bad sectors which is possible to the drive hardware and allow it to be
overwritten.
A few bits here and there might escape destruction by these means, but
also, arguably, a few bits on "known corrupted" sectors may prove very
little.
-----Original Message-----
From: Nathan R. Valentine [mailto:nathan@nathanvalentine.org]
Sent: Thursday, September 30, 2004 2:30 PM
To: forensics@securityfocus.com
Subject: Shred. Was: Securely wiping...
From the 'shred' info page:
<snip>
Generally speaking, it is more reliable to shred a device than a
file, since this bypasses the problem of filesystem design mentioned
above. However, even shredding devices is not always completely
reliable. For example, most disks map out bad sectors invisibly to the
application; if the bad sectors contain sensitive data, `shred' won't
be able to destroy it.
</snip>
I guess that means that I can go outside this weekend. ;)
--
Nathan R. Valentine <nathan@nathanvalentine.org>
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