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Date:      Sun, 06 Jan 2002 16:10:52 -0800
From:      "Kevin Oberman" <oberman@ptavv.es.net>
To:        Scott Mitchell <scott.mitchell@mail.com>
Cc:        Anthony Atkielski <anthony@freebie.atkielski.com>, Cliff Sarginson <cliff@raggedclown.net>, FreeBSD Questions <freebsd-questions@FreeBSD.ORG>
Subject:   Re: Parts I recommend (formerly "Workstation and server-market") 
Message-ID:  <20020107001052.B29255D2D@ptavv.es.net>
In-Reply-To: Your message of "Sun, 06 Jan 2002 12:10:09 GMT." <20020106121009.A338@localhost> 

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> Date: Sun, 6 Jan 2002 12:10:09 +0000
> From: Scott Mitchell <scott.mitchell@mail.com>
> Sender: owner-freebsd-questions@FreeBSD.ORG
> 
> On Sun, Jan 06, 2002 at 08:29:03AM +0100, Anthony Atkielski wrote:
> > Cliff writes:
> > > Don't live in the same room as a server with
> > > SCSI drives though. They are significantly noisier
> > > than ATA ones.
> > 
> > The only difference between them is in the electronics, so I don't know why
> > they'd be noisier.
> 
> I'd not be so sure that they're mechanically identical -- IME the failure
> rate for ATA drives is much higher than the SCSI ones, despite the fact
> that the SCSI server drives do a lot more work than the ATA units in the
> workstations.  Of course most SCSI drives are going to be running at 10Krpm
> or above, while your typical ATA drive does 5400 or 7200rpm, so there's
> some extra noise for you right away... I suspect there might be some
> mechanical differences between a drive that has to run reliably for years
> at 15Krpm and one that's idle half the time at 5400rpm in someone's
> desktop.

They are sometimes similar and do share many part, but, even on close
to "identical" drives, there are differences (or were, the last time I
looked into drive manufacturing).

First, and probably most significant, is sound level. Most SCSI drives
are aimed at the server market and not the office. As a result, there
is no sound deadening built into them. While the addition of sound
deadening does not effect performance much, it does really impact
reliability. It impedes heat transfer and makes the driver run hotter.

Other differences include faster (and more robust) positioning motors,
different head acceleration profiles (beyond that enforced by the
cheaper hardware) to further quiet the drive, and larger spindle motors.

In recent times the SSI market has moved to much more differences due
to things like faster rotation, but even then, many mechanical
components are identical.

The cost differential is also growing since ATA drives are built in
MUCH larger numbers and targeted toward the low end of the market
(desktops). Profit margins are probably MUCH thinner on ATA drives.

R. Kevin Oberman, Network Engineer
Energy Sciences Network (ESnet)
Ernest O. Lawrence Berkeley National Laboratory (Berkeley Lab)
E-mail: oberman@es.net			Phone: +1 510 486-8634

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