hard drive data recovery

From: Allison J Parent <allisonp_at_world.std.com>
Date: Sun Jul 12 13:50:38 1998

< However, a book on metal casting at home (did I mention I have other
< insane interests...) mentions that vacuum cleaner motors produce a
< reasonable pressure, but not that much air flow. It suggests a better
< choice is a car heater fan motor. Those are also easy and cheap to get,
< of course.

It would, however a glove box of 8cuft (2x2x2) would not require much air
flow once "cleared" and the remaining air needed is only that required to
provide some trivial positive pressure to then insure clean air flows out
and dirty air does not get sucked in. For that volumes in the 2-10cfm
level is all than is needed. the positive pressure needed is on the order
of 0.1" water. A vacuum motor is if anything over doing it as they are in
the 200-500 cfm range.

< Yep... That's the drive I rebuilt over the air stream from the RK07 :-).

I've done a bunch of them and I just clear my work area and go to work.

For the paranoid a vacuum with a hepa filter on the output blowing down on
the work area might be in order but take care to not stir up dust.

< I think it's going to be important to be able to do this in the future.
< They'll come a point when there are no (say) Micropolis 1200s working,
< but enough non-working ones lying about to be able to be able to make 2
< or 3 into a good one.

A glove box is trivial to build. I'd use a 25 CFM blower and a small hepa
filter and the box could be made with LEXAN (clear plastic) glued with RTV
and cleaned well. the front would be a curtain of 6mil poly with velcro
holding it to the edges. Holes would be provided to allow reaching in with
plastic gloved hands. The hole to not have to be air tight around the
gloves and the positive airflow in in the box would insure air flows out.

Hint: filter is on the output side of the blower forcing air into the box
and the outflow is through a coarse filter to limit outflow.

< For that reason, maybe we should start keeping dead hard drives....

To perfect technique. Getting the right tools is half the battle.

< Sure... I was pointing out that fixed (not sprung) heads -> higher flying
< height (due to runout) -> lower density. Not that drums are always low
< density devices.

understood. Keep in mind the old fixed head drums were mecanically crude
devices and magnetics were not well understood as yet.

< I wonder why, therefore, that service manuals on winchesters always say
< that you can't work on the insides of the HDA outside a clean room
< (which, by implication, you don't have). Even when the same manufacturer
< made demountable drives and did include instructions for head replacement
< on those.

Because if you making 500-1000 drives a day tossing 10-20 for damage due
to someone sneezing is far to costly. Also they have to insure they are
clean. But the level of clean needed is low. A hair net, nylon dust free
gloves, no facial hair and a dustmask over the nose and mouth would
eminimate 90% of human sources. Also not putting finger prints or other
debries on the disk is a must as rag wiping is already far to filthy.

there is care and there is paranoia. For example did you know that ESD
is damaging to magnetic media? If you deliver a hard spark to the plated
media you may pit it some or at least remagnetize a small area, disaster
for servo tracks.

FYI/note: Why do ALL drives spin up then load the heads? It's to allow
the airflow from the spinning media to establish the clean airflow inside
the drive. Also any dust on the active portion of the media spins off the
media and is then captured in a filter.


Allison
Received on Sun Jul 12 1998 - 13:50:38 BST