Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!ames!ncar!asuvax!mcdphx!mcdchg!ddsw1!ddsw1!point!wek
From: wek@point.UUCP (Bill Kuykendall)
Newsgroups: comp.sys.ibm.pc
Subject: Re: COBOL, power cycles, and hard disks
Keywords: COBOL for PCs, acceptable power cycling, manual disk parking
Message-ID: <[2660.4]comp.ibmpc;1@point.UUCP>
Date: 25 Oct 89 17:00:10 GMT
References: <4005@cbnewsc.ATT.COM> <[25451d0c:6247.3]comp.ibmpc;1@ddsw1.MCS.COM
Lines: 32

>(2) My understanding is that frequent power cycling (i.e. shutting off
>    the PC/AT whenever it's not in use) cannot cause damage to or
>    in any other way hasten the wearing out of any part of the PC.
>    Is this really true?  Or is it better for the machine to leave
>    it running 24 hours a day as much as possible?

Leave it running.  The hard disk is essentially an electric motor with a set
of flywheels attached to (mechanically).  During powerup acceleration there
is thrust on the spindle that wears the thrust washers and eventually allows
the platters to contact the heads.  There is also a spindle brake which
activates when you shut the drive down that can get stuck when the bushing
in the actuating solenoid wears (the brake spindle cocks in the bushing,
causing it to bind).  There are dozens of reports populating the net about
drives that need to be manually nudged or allowed to sit with the power on
for awhile before they'll spin up.  This is the cause.  

Power your monitor off though (unless it's a Monoterm!) so that the screen
doesn't get burnt in.

>(3) I've gotten conflicting information on the necessity of manually parking

>    the hard disk heads before powering down the machine.  Some

Others have said it -- it depends on the drive.  You'll have to ask the
manufacturer.


---------------
Bill Kuykendall
Chicago, IL USA
 ...!point!wek
wek@point.UUCP