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Subject: Re: [cygwin] DD bug fails to wipe last 48 sectors of a disk
To: Hashim Aziz <hashaziz@hotmail.com>, cygwin <cygwin@cygwin.com>
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From: Eliot Moss <moss@cs.umass.edu>
Message-ID: <239d7547-efe8-4b59-6f4f-8a387baf8048@cs.umass.edu>
Date: Tue, 23 Jun 2020 11:29:45 -0400
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On 6/23/2020 11:28 AM, Hashim Aziz via Cygwin wrote:
> I hadn't checked with 512 byte block sizes because of the amount of time it would have taken, but sure enough have just finished trying with bs=512 and no block size at all (so dd's default block size, which is either 512 or 1024) and although each wipe took over 24 hours, they did indeed wipe all of the sectors. So it seems that there's a bug with regards to how Cygwin handles the last block when a large (i.e. sane) block size is selected, and that this bug doesn't occur on actual UNIX-based systems.

Well, that certainly points the finger at last-block handling ... EM
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