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Date:      Sat, 12 Feb 2011 21:42:33 -0800
From:      Julian Elischer <julian@freebsd.org>
To:        perryh@pluto.rain.com
Cc:        jhs@berklix.com, hackers@freebsd.org
Subject:   Re: memstick.img is bloated with 7% 2K blocks of nulls
Message-ID:  <4D576F49.5030201@freebsd.org>
In-Reply-To: <4d5753d7.BT5wqP8CnfTD02s8%perryh@pluto.rain.com>
References:  <201102111909.p1BJ9UAE097045@fire.js.berklix.net>	<66758C9D-DCE2-4381-A4B1-956A48423CDD@kientzle.com> <4d5753d7.BT5wqP8CnfTD02s8%perryh@pluto.rain.com>

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On 2/12/11 7:45 PM, perryh@pluto.rain.com wrote:
> Tim Kientzle<tim@kientzle.com>  wrote:
>
>> The strategy used by libarchive's recent ISO writer
>> is to concatenate the file bodies into a temp file
>> (with minimal padding between entries to meet alignment
>> requirements) while storing directory information
>> in memory.  The final output then consists of the
>> directory information followed by the concatenated
>> file bodies.
>>
>> I suspect a similar strategy could be used to lay
>> out and write a read-only optimized UFS image ...
>> I think it's probably feasible but I doubt very
>> much of the existing UFS code can be recycled for
>> such a project.
> There was at one time a capability in mkfs(8) -- which no
> longer even exists as a separate entity, having been absorbed
> into newfs(8) -- to pre-populate the filesystem with specified
> content.  Dunno if it was ever in any BSD release -- it's not
> mentioned in the 4.2BSD-derived SunOS 4.1.1 manpage -- so
> I may be remembering it from Bell Labs 6th edition on the PDP-11.

man makefs

> The code to collect and write all of an existing filesystem's
> directories, followed by all of its files, exists in dump(8).
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