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Date:      Sun, 22 Jul 2012 17:45:00 -0500
From:      Adam Vande More <amvandemore@gmail.com>
To:        Jakub Lach <jakub_lach@mailplus.pl>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: "da0: 40.000MB/s transfers" What was rationale behind pegging USB 2.0 at 40MB/s?
Message-ID:  <CA+tpaK3qWnh_MUfBAEzTexsJdXu4JP5nPG=z4jJdUUd2qwSUxQ@mail.gmail.com>
In-Reply-To: <1342992043358-5729028.post@n5.nabble.com>
References:  <1342992043358-5729028.post@n5.nabble.com>

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On Sun, Jul 22, 2012 at 4:20 PM, Jakub Lach <jakub_lach@mailplus.pl> wrote:

> Hi,
>
> I was fortunate enough to buy USB 3.0 pendrive,
> which actually works with FreeBSD just ripped from
> package! (normal _empty_ FAT filesystem, no
> garbageware added, no need to format).
>
> It actually bounces from 40MB/s limit when reading
> from it.
>
> Writing is about 18MB/s.
>
> Device is supposed to be "467x" which should
> be about 70MB/s.
>
> And USB 2.0 hard limit is 60MB/s.
>
> Wouldn't be nice to squeeze few additional
> MB/s?
>

You are suffering a misunderstanding of how USB 2 works.  There is a lot of
overhead to it.  If you want USB 3 speeds, buy a USB 3 controller.
-- 
Adam Vande More



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