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Date:      Sun, 10 Jun 2012 20:15:52 -0400
From:      Robert Huff <roberthuff@rcn.com>
To:        "Ronald F. Guilmette" <rfg@tristatelogic.com>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: Making a bootable backup (hard)disk... how?
Message-ID:  <20437.14520.364554.528919@jerusalem.litteratus.org>
In-Reply-To: <48774.1339367039@tristatelogic.com>
References:  <alpine.BSF.2.00.1206100543280.75580@wonkity.com> <48774.1339367039@tristatelogic.com>

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Ronald F. Guilmette writes:

>  Warren?  Just a couple more quick questions.  You recommend:
>  
>  >>   dump -C16 -b64 -0uanL -h0 -f - /usr | (cd /mnt && restore -ruf -)
>  
>  I'm real curious about you suggestions for the -C and -b values.
>  
>  I have what amounts to a personal workstation.  Yea, OK, it is running
>  mail, web, and FTP servers also, but fundementailly, it is not that busy
>  most of the time.  And it's got 4GB of main installed.  On average, I
>  suspect that I ain't even using half of that.
>  
>  Given all that, why shouldn't I specify (e.g.): -C512 -b1024  ?
>  
>  Wouldn't that all make the dump go faster?

	There are many possible obstacles to faster dump speed;
enumerating them is left as an exercise for the reader.
	As it happens, I have a set-up very similar to what you
describe ... except with 8g of memory.  A few years ago I did some
testing with various cache sizes (as part of diagnosing other
problems) and ended up with C=32.
	(I should probably run the tests again, given some hardware
changes since.)
	That machine's level 0 runs tonight; I will try to remember to
(retain and) post the results.



					Robert Huff



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