[Beowulf] Re: failure trends in a large disk drive population

Richard Walsh rbw at ahpcrc.org
Wed Feb 21 10:06:17 EST 2007


Mark Hahn wrote:
>>   Not sure the vapor pressure of the perfluoroethers that they use as 
>> lubricants
>>   varies that much over the operating temperature regime of a disk 
>> drive.
> on the other hand, do these lubricants tend to get sticky or something
> at lowish temperatures?  the google results showed significantly greater
> failures in young drives at low temperatures.  (as well as extreme-temp
> drives when at end-of-life.)
>
Hey Mark,

Good question.  The properties of perfluoropolyethers (Krytox, Fomblin, 
Demnum)
must be well-known, but the Googling I did yielded only a single 
reference on
point which I did not want to pay for.  The ambient temperature range in 
the study
is pretty small which would limit viscosity variation, but when the head 
arrives
at a long unread location on a cooler disk maybe there are some shear 
effects.

Any disk drive vendors read this list and care to comment?

rbw

-- 

Richard B. Walsh

"The world is given to me only once, not one existing and one
 perceived. The subject and object are but one."

Erwin Schroedinger

Project Manager
Network Computing Services, Inc.
Army High Performance Computing Research Center (AHPCRC)
rbw at ahpcrc.org  |  612.337.3467

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