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Date: Sat, 12 Feb 2005 14:04:52 +0100
From: Charles Longeau <clongeau@gmail.com>
Subject: Re: [Qemu-devel] image size - OS reports 720mb,
	but image file is 2.3 gig
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To: qemu-devel@nongnu.org

Hello,

> You need to make sure all the unused space on the
> image is actually zeroed.
> 
> One way to achieve this would be to shrink the guest partition to its minimum
> size, then create a second partition on the unused space and explicitly zero
> that out (using dd from knoppix if necessary).

I think there is a easier way to zero unused space on an image or partition.

Mount the image/partition
cd into it
cat /dev/zero > dummy_file
(Wait until error : No space left on device)
rm dummy_file

Hope it helps,

Best regards,

Charles Longeau