From: Michael Smith <msmith@atrad.adelaide.edu.au>
Message-Id: <199512021853.SAA21270@genesis.atrad.adelaide.edu.au>
Subject: Re: No Thumbs??? (lack of concensus)
To: jkh@time.cdrom.com (Jordan K. Hubbard)
Date: Sat, 2 Dec 1995 18:53:52 +0000 ()
Cc: dgy@rtd.com, freebsd-hackers@freefall.freebsd.org
In-Reply-To: <3594.817858677@time.cdrom.com> from "Jordan K. Hubbard" at Dec 1, 95 02:57:57 pm
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Jordan K. Hubbard stands accused of saying:
> 
> > Yeah but power is power.  If you dissipate 10 - 15W, it doesn't matter
> > *what* is dissipating the power!  So, 2X would be in the 20 - 30W range
> > (comparable to the tape drive).
> 
> Actually, you and I both know that's not true because we know that
> power dissipation is only part of the equation.  There's also the
> question of *where* the power is turning most fully into heat and how
> effective your air conditioning (or other heat transfering
> metal-to-metal contact) is at that point.

And you're not considering duty cycle either, nor average vs. peak
power consumption, or thermal mass for that matter.  It's not that disks
produce lots of heat, more that they _dispose_ of it poorly, so over 
time they become quite hot.  A tape drive, on the other hand, produces most
of its heat in the various motors involved, which are open to the air
and thus dissipate their heat more easily.

> 					Jordan

Jordan was right on the money with disk drives != tape drives.

-- 
]] Mike Smith, Software Engineer        msmith@atrad.adelaide.edu.au    [[
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