[CentOS] External harddisk

Wed Sep 30 16:15:41 UTC 2020
Valeri Galtsev <galtsev at kicp.uchicago.edu>

On 2020-09-30 10:55, Mark (Netbook) wrote:
> Since you have taken the disk apart it will now be useless as within the 
> enclosure there could have been a vacuum or an inert gas.

No, old drives were filled with air usually, and were connected to 
exterior atmosphere via porous barrier. That is why regular drives are 
much more likely to fail up in the mountains, say where the is about 1/2 
of normal atmospheric pressure. Pressure inside ordinary drive is the 
same as external pressure, and heads are just spring loaded and are 
resting on platter surface, and are pushed away from it when platters 
spin (hence so called "parking track" ). Air works as viscous liquid at 
these relative speeds, and the law is at least cubic, so at 1/2 
atmosphere heads are much closer to platter surface. Therefore, failures 
are quite likely. Sealed drives are still not wide spread, He (helium) 
filled would be one type. But sealed drives existed even some 25+ years 
ago (to be used at Astronomy observatories high in mountains, e.g.). I 
remember HP drives of that kind that costed $10k apiece back then, and 
those dollars, not today's dollars.

What you are right about is: the drive upon opening got contaminated 
with solid dust particles, and will not serve long. But fair chance is, 
one still will be able to get data off it.

> You will never be able to recover any data on the disk unless you go and 
> pay for a professional data recovery organisation to read the platters.

While he may be able to recover data, professional recovery are more 
likely to succeed. They will be not happy to work with drive that was 
opened not in a "clean room", and my charge more. Be it I, I definitely 
will tell them that drive was opened not in clean room, they will know 
anyway once they have drive.


> The price for a replacement 340GByte USB disk is about $25 which would 
> give you a better product than your old disk.
> Mark
> -----Original Message----- From: H
> Sent: Wednesday, September 30, 2020 4:47 PM
> To: centos at centos.org
> Subject: Re: [CentOS] External harddisk
> On 09/30/2020 05:40 AM, John Pierce wrote:
>> On Tue, Sep 29, 2020, 8:33 AM H <agents at meddatainc.com> wrote:
>>> I have an old external harddisk, Toshiba 320 Gb, with a USB connector 
>>> that
>>> I wanted to check for contents. It did not start up when connected and I
>>> could not hear the motor spinning. After leaving it in the freezer
>>> overnight the motor spins but it is not recognized by my computer. I
>>> disassembled it and could see that the head assembly rests outside 
>>> the disk
>>> but when it is powered on, the head first moves to the center of the 
>>> disk,
>>> then to the periphery and finally back to the resting position. This
>>> happens every few seconds and leaving it connected overnight changed
>>> nothing.
>> That repeated seeking suggests it's not passing its self test, and is
>> constantly retrying.   It's probably searching for servo data on the 
>> disks,
>> and not finding it.
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> I see. I have not searched for any low-level disk utility from Toshiba, 
> the manufacturer of the disk. Do you think that might be worthwhile to 
> hopefully fix this?
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Valeri Galtsev
Sr System Administrator
Department of Astronomy and Astrophysics
Kavli Institute for Cosmological Physics
University of Chicago
Phone: 773-702-4247