Thanks to all people who replied. Their comments are very much appreciated.
The following is a summary of the answers I got. I tried to order them as much
as I could. They are part my words and part (a large one) the words of all
people who reply to my original message. They will probably recognize their
thoughts and opinions. Most people agreed dust could have an impact on the
system. There was only one person that disagreed. I did not include his
comments here.
Once again. Thanks a lot
Carlos Perez
------------------------------------------------------------------------------
Can Dust damage a disk drive ?
* The impact of Very Fine Particles on a disk drive
Gypsum or Calcium Sulfate dust can damage a Winchester disk drive if the size
of the dust particles is less than five microns. Modern disk drives are
supposed to be sealed from the environment -no air exchange is supposed to
take place-; however, almost all drives -the WREN IV in the Sun 386i not being
an exception- have a set of very little ventilation holes which are protected
by a five micron mesh. With some biological viruses being larger than that,
one may be inclined to believe that 'nothing goes inside of the drive'.
Gypsum and asbestos dust (and dust from other materials) can include Very Fine
Particles (VFP) whose sizes may be smaller than 3 microns -just about the
right size to go through the ventilation holes-. Once inside of the drive, the
dust particles may interpose themselves between the disk head and the
recording surface. The heads and the recording surface will gradually abrade
away, causing location-specific errors which progressively spread across the
disk surface, as David C. Woodruff <dcw@WLV.IIPO.GTEGSC.COM> explains.
In addition, large amount of gypsum dust could also have blocked the
ventilation holes on the disk pack. As a consequence, the disk will fail
because overheating. Again, it is worth mentioning that any drive with
ventilation holes will have a clear warning from the vendor not to cover the
vents. In fact, as Andrew Luebker <aahvd@eye.psych.umn.edu> suggests, is not a
very good idea to tap the disk defect-list over the holes!
Moreover, with the ventilation holes being blocked, with the gypsum dust
being highly soluble, and dust with attracting moisture; we could have a
situation where the holes may be actually 'plastered'. Consequently, the disk
will fail because overheating.
Instances of dust making disk drives to fail -because the dust went inside of
the disk- have been reported by Ed Arnold <era@ncar.ucar.edu>. He carefully
points out that these drives were not sealed.
* The impact of gypsum dust on the Electronic Components
Gypsum dust inside of the computer will also produce a fine coating over the
electronics of the drive. The coating may act as a heat insulator causing
parts of the drive to overheat. Heat, over time, may destroy some of
the electronics, such as the sense amplifiers from the read/write heads,
as Dr. Robert Pasken <pasken@newton.slu.edu> suggests. Bill Morrow
<morrow@cns.ucalgary.ca> also mentions that the NVRAM which holds, among other
things, the motherboard revision information, is infamous for dying if it gets
too hot.
Dust causing the electronics to fail has also been reported from several
sources : Tobias Weingartner <weingart@tau.inf.ethz.ch> explains that Sun3/50
and Sun3/60's, which have been accumulated dust over time, will fail
when moved/shaken. The failure is reported as RAM parity errors that will
eventually crashed the workstations. Joe Murray <murray@akeila.mech.utah.edu>
also explains that a Sparc1+ failed dues to fiberglass dust, according to the
Sun technicians. No attempt was made to explain how this kind of dust affected
the electronics.
* The impact of Dust on the ventilation system
Dust can clog the mesh in front and behind the fans, reducing the air flow
causing the disks to overflow and fail. The Sun 386i is particular prone to
this problem. The dust screen at the front of the chassis is is quite easily
clogged with dust and the machine's cabinet is poorly designed with respect
to ventilation ( Sverre Slotte <sverre@research.nokia.fi> reports that he
obtain this information from Sun dealer). In addition, the WREN IV is being
known to be very sensitive to overheating. In short, several people have
reported disk problems, on Sun 386i's, due to overheating, which in turn is
due to dust blocking the machines's fans.
* The impact of dust on Mechanical system
The dust could have gone into the bearings thus decreasing the efficiency of
the cooling system.
* The impact of dust on the software system
One thing is hard to believe is that a software condition will cause a
hardware fault that could not be corrected by reloading the operating system.
ACK:
From: David Fetrow <fetrow@biostat.washington.edu>
From: weingart@inf.ethz.ch
From: sverre@research.nokia.fi (Sverre Slotte Jr.)
From: blymn@mulga.awadi.com.AU (Brett Lymn)
From: Mr T Crummey (DIJ) <tom@sees.bangor.ac.uk>
From: lem@usb.ve (LDC - Luis E. Mun~oz)
From: dzambon@afit.af.mil (Dan A. Zambon)
From: matt@wbst845e.xerox.com (Matt Goheen)
>From peb%sandoz@scdipc0.ueci.com Tue Mar 9 09:26:52 1993
From: "Jon Mellott" <jon@alpha.ee.ufl.edu>
From: Wade Smith <wsmith@imagine.convex.com>
From: Paul Lemman <lemmanp@ohsu.EDU>
From: mckibben@witch.nssl.uoknor.edu (Loretta McKibben)
From: Ray Schnitzler <ras@unipress.com>
From: Jay Plett <jay@silence.princeton.nj.us>
From: dcw@WLV.IIPO.GTEGSC.COM (David C. Woodruff)
From: danny@ews7.dseg.ti.com
From: poffen@sj.ate.slb.com (Russ Poffenberger)
From: morrow@cns.ucalgary.ca (Bill Morrow)
From: birger@vest.sdata.no (Birger A. Wathne)
From: boes@corona.AuE.com (Barry A. Boes)
From: murray@akeila.mech.utah.edu (Joe Murray)
From: "Dan Franklin" <dan@diamond.bbn.com>
From: dunstan@gec-epl.co.uk (Dunstan_Vavasour)
From: unixsys@ssg.com (Rick Emerson)
From: era@ncar.ucar.edu (Ed Arnold)
From: "Andrew Luebker" <aahvdl@eye.psych.umn.edu>
From: ekurgpol@develop-law.usc.edu (Elmar Kurgpold)
From: tpriddy@mipos3.intel.com (Tim Priddy )
From: vasey@issi.com
From: Adrian Booth <abcc@DIALix.oz.au>
From: pasken@newton.slu.edu (Dr. Robert Pasken)
From: ext_adm!jmcgrath@uunet.UU.NET (John Mc Grath)
From: laz@cheetah.ece.clarkson.edu (Matt Parker - N2MGI)
From: Geert Jan de Groot <geertj@ica.philips.nl>
From: "David T. Hightower" <hightowr@cadre.af.mil>
From: ron@drd.com (Ron.Madurski)
Anybody else I may have omitted by mistake.
This archive was generated by hypermail 2.1.2 : Fri Sep 28 2001 - 23:07:38 CDT