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From: russotto@eng.umd.edu (Matthew T. Russotto)
Newsgroups: comp.sys.mac.hardware
Subject: Re:  Leaving Mac On
Message-ID: <1991Feb15.214147.8321@eng.umd.edu>
Date: 15 Feb 91 21:41:47 GMT
References: <22085@hydra.gatech.EDU>
Sender: news@eng.umd.edu (C-News)
Organization: College of Engineering, Maryversity of Uniland, College Park
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In article <22085@hydra.gatech.EDU> gt4586c@prism.gatech.EDU (WILLETT,THOMAS CARTER) writes:
>The most cogent reason I've seen for turning off the mac is the possibility
>of excessive wear on the spinning hard drive.  How well engineered are the
>hard drives in that regard?
Most hard drives fail during spinup and spindown, or die due to stiction.
Leaving them on will help them as well.

> How many spin hours can they be expected to
>last?

According to the docs on my WREN-IV, 100,000 continuous hours.  The specs for
your drive, obviously, may be different.

>Lastly, is it feasible to create a "sleep" mode for your computer
>in which the hard drive spins down but the CPU stays on to keep warm?

I suspect that the portable does this, to conserve power.  The SCSI spec seems
to implement two commands, Start and Stop, that could be used for this purpose,
but since the mac doesn't send a Start on boot, this may not be a feasible
solution (I'm a bit fuzzy on this part)
--
Matthew T. Russotto	russotto@eng.umd.edu	russotto@wam.umd.edu
     .sig under construction, like the rest of this campus.