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Date:      Thu, 28 Mar 2013 09:12:45 +0000
From:      Steve O'Hara-Smith <steve@sohara.org>
To:        freebsd-questions@freebsd.org
Subject:   Re: Copying memstick image to a USB (flash/thumb) drive
Message-ID:  <20130328091245.c5eecadea50b45f92e8363db@sohara.org>
In-Reply-To: <5153FEFF.4090305@sneakertech.com>
References:  <14008.1364453112@server1.tristatelogic.com> <5153FEFF.4090305@sneakertech.com>

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On Thu, 28 Mar 2013 04:27:43 -0400
Quartz <quartz@sneakertech.com> wrote:

> 
> > I have filed the following PR:
> >
> > http://www.freebsd.org/cgi/query-pr.cgi?pr=177431
> 
> Er, don't take my word for law: I have *no* idea if 1M is a good idea 
> for most systems, I'm not even sure if it's optimal for mine. I did a 
> single test with three random values at different orders of magnitude 
> and picked the fastest. I do think that 10k is probably way under the 
> right value, but someone should do proper testing on a variety of 
> hardware before changing all the docs.

	The 1M will work fine, it's way bigger than any physical write. In
theory the performance should max out when the block size matches the
maximum physical write size of the controller (often 64K), but that assumes
zero read latency on the data feed so in practice larger block sizes help,
but except for things like tape they don't help much once you pass the
device/controller max write block size.

-- 
Steve O'Hara-Smith <steve@sohara.org>



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