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Date:      Wed, 14 Nov 2001 09:07:46 -0600 (CST)
From:      Chris Dillon <cdillon@wolves.k12.mo.us>
To:        Bill Vermillion <bv@wjv.com>
Cc:        <stable@FreeBSD.ORG>
Subject:   Re: ATA hard drives
Message-ID:  <Pine.BSF.4.32.0111140856470.12336-100000@mail.wolves.k12.mo.us>
In-Reply-To: <20011114051132.A12369@wjv.com>

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On Wed, 14 Nov 2001, Bill Vermillion wrote:

> Just a comment on rotational speed.  You should always check the
> manfacturers specs as the design of the head can greatly affect
> the speed of transfer to/from the platters.  I have seen 5400 RPM
> drives move data faster than 7200 RPM drives.  You don't see it
> often but RPM alone is not sole determining factor as much as
> legend would make you think it is.

Data rates aren't the only factor.  It is true that higher RPM doesn't
necessarily mean higher data rates since you can have a lower-RPM
drive with a high areal density resulting in a higher transfer rate
compared to a higher-RPM drive with lower areal density.  However, the
higher RPM drive does have a lower rotational latency, so it takes
less time for the section of the platter with the data on it that you
want to come under the head, which lowers the overall latency of the
drive.

--
 Chris Dillon - cdillon@wolves.k12.mo.us - cdillon@inter-linc.net
 FreeBSD: The fastest and most stable server OS on the planet
 - Available for IA32 (Intel x86) and Alpha architectures
 - IA64, PowerPC, UltraSPARC, and ARM architectures under development
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