Path: utzoo!attcan!uunet!tektronix!sequent!mntgfx!mikes
From: mikes@mntgfx.mentor.com (Mike Stanbro)
Newsgroups: comp.sys.ibm.pc
Subject: Re: Leaving the hard disk on continuously
Message-ID: <1988Jul19.153220.854@mntgfx.mentor.com>
Date: 19 Jul 88 22:32:17 GMT
References: <12184@agate.BERKELEY.EDU>
Organization: Mentor Graphics Corporation, Beaverton Oregon
Lines: 41

From article <12184@agate.BERKELEY.EDU>, by cotner@jif.berkeley.edu (Carl Cotner):
> After some recent discussions and testimonials on the net, I've been
> convinced that I should leave my PC and hard disk on 24 hours a day
> to spare it the trauma of being powerred it on and off each time I 
> use the machine.  
> 

Here's a wild thought I had several months ago but never pursued it because it 
seemed a bit risky.  There are two voltages to hard disks: +5V and +12V.  
The +5V powers all of the electronic circuits, the +12V powers the spindle motor and
actuator motor or coil.  If you shut the +12V off and leave the +5V on, the spindle 
motor will shut down but the disk remains "intelligent" and will continue normally 
after the +12V is reapplied and the platters spin back up to speed.

What do you think about a "black box" that plugs in-between the hard disk and the 
power supply cable and controller cables.  My idea is to have a timer in the black 
box that senses the select signal going to the hard disk.  As long as the select 
signal is toggled every now and then, the black box does nothing out of the ordinary.  
If the select line is inactive for more than a pre-established cut-off period 
(maybe 2 hours), the black box cuts off the +12V to the spindle motor to save 
wear on the bearings of the spindle and the spindle motor.  But wait ... there's
more ... when the select line goes active again, the black box reapplies the power
to the motors and the disk spins back to life.

I tried this with a manual switching setup.  The only oddity is that DOS times-out
waiting for the hard disk to respond and issues the familiar message you have seen 
from floppy drives: "Drive not ready:  Abort, Retry, Ignore".  If you wait for a
second or two until the drive is at full speed, then issue a "retry" response, 
everything seems to work great.

Well guys ... is that a wild idea or what?

Mike Stanbro, Research Engineer                     (503) 626-1437
Mentor Graphics Corp., 8500 SW Creekside Place, Beaverton OR 97005
...!{sequent,tessi,apollo}!mntgfx!mikes   OR  mikes@pdx.MENTOR.COM
These are my opinions, & not necessarily those of Mentor Graphics.
-- 
Mike Stanbro, Research Engineer                     (503) 626-1437
Mentor Graphics Corp., 8500 SW Creekside Place, Beaverton OR 97005
...!{sequent,tessi,apollo}!mntgfx!mikes   OR  mikes@pdx.MENTOR.COM
These are my opinions, & not necessarily those of Mentor Graphics.