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Date:      Fri, 4 Oct 2002 09:33:28 -0500
From:      Dan Nelson <dnelson@allantgroup.com>
To:        "Jacob S. Barrett" <jbarrett@amduat.net>
Cc:        freebsd-questions@FreeBSD.ORG
Subject:   Re: Block Zeroing Tool
Message-ID:  <20021004143328.GC21868@dan.emsphone.com>
In-Reply-To: <3D9DA621.2080201@amduat.net>
References:  <3D9DA621.2080201@amduat.net>

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In the last episode (Oct 04), Jacob S. Barrett said:
> Is there a tool for FreeBSD that zeros the unallocated blocks on a
> filesystem?
> 
> The company I work for has an image on demand system for our lab
> machines.  This system relies on ghost which only supports file by
> file imaging on certain file systems.  I want to take disk images of
> certain FreeBSD installations.  Ghost will only take sector by sector
> images of FreeBSD partitions.  Since it is doing this it stores all
> the "junk" unused blocks as well.  This makes for a very large image
> even with high compression.  If I can zero out the unused blocks
> before taking the image with high compression the image size should
> be much smaller.
> 
> So, is there utility to zero out those blocks?  Does this make sense? 
> Is there a better way to take images of FreeBSD machines?

dd if=/dev/zero of=filler bs=1m ; rm filler

-- 
	Dan Nelson
	dnelson@allantgroup.com

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