Re: Re: Strange Screws
- From: "J. Clarke" <jclarke.usenet@xxxxxxxxxxxxxxxx>
- Date: Wed, 18 Jan 2006 08:59:02 -0500
Rob B wrote:
>
> "J. Clarke" <jclarke.usenet@xxxxxxxxxxxxxxxx> wrote in message
> news:dqkjp901pbd@xxxxxxxxxxxxxxxxxxxx
>> Stan Blazejewski wrote:
> <snip>
>>
>> Examine that filter carefully and you will find that its primary function
> is
>> to filter the tiny amount of air moving through the pressure-equalization
>> hole and that there is no mechanism by which all or any significant
> portion
>> of the air circulating inside the capsule can be made to pass through it.
>>
>> > The 'new' drives I've pulled apart for the magnets seem to have the air
>> > filters as well although I'd expect today's technology to be less
> tolerant
>> > to dirty air what with the amount of data that they pack into the
> smaller
>> > space but I still wouldn't expect it to die in "a few days or weeks".
>>
>> It dies as soon as something hard enough to scratch the platter or head
> and
>> small enough to get wedged between them finds its way into that space.
>>
>> In the real world people have tried this, and the drives typically died
>> in anywhere from a few hours to a few weeks.
>>
> <snip>
>
> the Math-CS dept at my alma-mater had pretty poster depicting the
> magnified size of various particles hair, dust, skin cell and smoke
> particles next to
> the disk heads and the cushion of air that head float on and if i
> remember correctly the smoke particle would barely squeeze between the
> head and platter
>
> guessing you were dust lucky with the drive surgery
Not me, the only time I've opened drives either they were already dead or
they were old drives being used as show-and-tells when teaching a class.
Never expected them to actually run afterwards. But if you will google
the archive for this newsgroup I think you'll find some reports from people
who have done this to see how long the drive would run.
One thing that is really bad news is fingerprints. I've seen a fingerprint
rip the head off and toss it across the room (somebody decided to power up
a show-and-tell after it had been passed around the classroom).
If it's _thicker_ than the gap and not stuck down and not too massive it
just gets pushed aside. If it's brittle though it may shatter when it hits
the head and make smaller particles. If it's hard and massive enough then
it can chip or deform the head. If it's an insect you get ichor on the
platter and the result is similar to fingerprints.
Bear in mind that that poster dates from the days of removable disk packs,
when drives were _not_ sealed. Few minicomputers were installed in special
rooms and even mainframe shops generally didn't have laminar-flow positive
pressure clean rooms with airlocks. Nonetheless a standard operation was
for some guy in a suit and tie (if it was a corporate shop) or tie-dyed tee
shirt and jeans and hair down to his ankles (if it was a university shop)
to change disk packs and they ran a good long time despite such treatment.
That's the reason for the posters, to remind people of why that area was
supposed to be kept clean.
--
--John
to email, dial "usenet" and validate
(was jclarke at eye bee em dot net)
.
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