Parking disk drive heads

[Brooks Davis]

On Fri, Aug 19, 2005 at 10:11:30AM -0400, Bill Vermillion wrote:
> "Bits dont fail me now!" was what
> freebsd-hackers-request at freebsd.org muttered as he hastily typed
> this on Fri, Aug 19, 2005 at 12:00 :
> 
> >    1. Re: Parking disk drive heads (Glenn Dawson)
> 
> > Message: 1
> > Date: Wed, 17 Aug 2005 12:47:32 -0700
> > From: Glenn Dawson <glenn at antimatter.net>
> > Subject: Re: Parking disk drive heads
> 
> > At 11:32 PM 8/16/2005, m.ehinger at ltur.de wrote:
> > >Hi,
> 
> > >which is the correct way to park the hd head?
> 
> > Seagate drives park the heads automatically when they are turned
> > off. As far as I know, this applies to other manufacturer's
> > drives as well.
> 
> 
> To which he replied:
> 
> > Message: 2
> > Date: Thu, 18 Aug 2005 08:14:47 +0200
> > From: m.ehinger at ltur.de
> > Subject: Re: Parking disk drive heads
> 
> > I don't want to park them on turn off. I want to park them
> > before a possible strong shock which could cause damage and
> > unpark them afterwards.
> 
> The setups for parking heads pretty much went away when the move
> from MFM drive to ATA technology.
> 
> And if your are worried about a shock that could damage the drive,
> you will probably lose your computer at the same time.
> 
> Check the technical specs on current drives.  You will see that
> most will handled well over 100G shocks when not running, and
> usually far over 20G in operational mode.  Considering that
> 20G to the human body usually means death you aren't going to have
> to worry about losing drives to operating bumps unless you have a
> habit of dropping them in parachutes from airplanes. :-)

I've ruined at least one modern ATA disk without otherwise damaging the
laptop by hitting it too hard so this is not true.

> IOW - unless you are running some early ATA drives, shocks when
> running are something you don't have to really worry about, unless
> you plan to shove the entire computer off the desk when it is
> running with the power on.

This is exactly what the origional intends to protect against.  Nearly
all good laptop vendors are adding the necessicary hardware to their
systems these days.  At the end of the day, the data on your hard drive
is much worth more then the laptop so it's perfectly rational to save
the hard drive even if the machine will be toast.  For an economic
example, my corprate laptop is worth slightly less then one week's
pre-tax income.  It would take a lot more than one week to reconstruct
the data on it if not for backups and extensive use of remote revision
control systems for anything of importance.

-- Brooks

-- 
Any statement of the form "X is the one, true Y" is FALSE.
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