From: gryphon@openage.openage.com (The Golden Gryphon)
Subject: Re: WHEN TO TURN OFF MY MACHINE?
Organization: Open Age, Inc.
Date: Thu, 30 Jul 1992 21:26:57 GMT
Keywords: SWITCH, ON, OFF, :-)

matthews@oberon.umd.edu (Mike Matthews) writes:
>In article <1992Jul28.223237.28954@openage.openage.com> gryphon@openage.openage.com (The Golden Gryphon) writes:
>>It depends on whether you want the machine to take a lightning hit?
>>Actually there is a great debat over this, and I'll cover it later if I
>>get enough requests.  I'm too tired.

>I hope you also unplug the machine, since lightning doesn't really care much
>about whether the machine is on or not.  Might even wanna put some distance
>between the plug and the outlet, I've heard stories (not sure if they're true
>or not) about the lightning just kinda hopping the air.

>>My advice...

>>	Turn it off.

>I hope you also move your crontab jobs that occur at night into sometime
>during the day so Unix can do its periodic housekeeping.  I hope you also
>have a small drive so the constant power cycling won't hurt it *too* much
>(small physically, not storage-wise).

>It all comes down to whether or not you want to treat your Unix box like a
>PC, or like a Unix box.  Sure, some people are better off turning the
>machines off.  But giving blanket advice either way is bad, IMHO.

I really am tired.  And I really didn't want to answer this now, but I guess
it is probably best.  I really wanted to write this up properly, post it, and
then see if anyone wanted to buy it for a PC magazine.  Oh well, you can't
have everything, where would you put it.

	1) I've never seen lightning dammage unplugged electrical equipment.
	It doesn't make sense since something powered off if not "The path
	of least resistance"

	2) I've seen lightning do some really weird things, like hit the 
	building, run down the DCBB backbone, through an NIU, and smoke a
	VAX ethernet board.  Nothing else got dammaged.  So I can not
	just discount what was said above.  BTW I saw this happen I didn't
	just hear about it.

	3) I'm really tired.  I assumed (Yes I know I'm using THAT word) that
	he was talking about a PC with DOS/WIN.  I still wonder why I'm 
	reading comp.unix.*, but I'll figure it out.

	4) You can relocate cron jobs to run as start-up scripts if you
	really need that knid of house keeping.  Most people don't know
	what all their cron jobs do any way.  Still a bad idea to not let
	UNIX boxes run all the time.

	5) Are cron jobs worth having to "fsck" all your file systems when
	the power goes out.

Now the controversy. (Who care about spelling anyway!)

There are two sides to this, and I will attempt to provide both side of the
argument.  I have already stated my position.

1)	LEAVE IT ON ALL THE TIME!

	The reasoning behind this is that heating and cooling electrical
components can dammage them.  The way that this happens is that a crack 
develops on the silicon of the chip.  The metal traces run on top of the 
silicon.  This happens mostly when static discharges on a chip.  The static
electricity burns or cracks the silicon.  This usually does not effect the
metal traces unless it is a major break.  Minor ones can occur with no 
immediate impact on the system.

	When the system heats and cools the silicon and metal expand and
contract at different rates.  This can cause the metal tracings to break.
This leads to flakey HW. "It was running fine, then I turned it off for a
few minutes and it wouldn't boot.  Then I left it on for a few minutes and
warm booted it, and it worked."  

	Leaving the system on keeps the heat basically constant with respect
to room temperature changes.  This can protect your equipment.  This also
makes it more vulnerable to power spikes and lightning hits.  It also costs
bucks in electricity.  I know a computer doesn't draw a lot of power, but if you
leave it on 24 hours 365 days it adds up.  It also heats the house in summer,
and you have to cool that too.  Also minor, but also adds up.

	The only problems I've seen with modern HDD (less than 2 yrs old) is
that the grease on the bearing can break down through constant heating and
cooling.  This can cause the drive to stick if the grease breaks down too 
much.  However a spinning drive hitting the ground from 3' is much more likely
to die than one at rest.

2)	TURN IT OFF WHEN NOT IN USE

	No bad idea if you have an unstable power grid (like Montgomery County
Maryland) or frequent lighting storms with ground strikes (see last ()'s ).
You can protect against this if you have a good UPS, a power filter that will
ground out spikes and lightning, and shutdown software in case of extended
power outages.  

	This just about guarantees that you never have to clean your filesystems
because they will never be dirty.  It also means you will probably never have
to replace fried components when your computer system dies.


I will happilly (ACK Spelling again) answer any questions.  Please email me,
as I will be off the net for a few days.  I got work to do.  Now where did
I put that ...



-- 
The Golden Gryphon 				gryphon@openage.COM
Solve a man's problem and he has 1 less.        No incumbents in 92.
Teach a man to think, and all his problems are less.
Openage - The Premier SCO UNIX integrator in the Washington D.C. area