[Beowulf] Cooling vs HW replacement - fans
alvin at Mail.Linux-Consulting.com
Mon Jan 17 01:55:18 EST 2005
On Sun, 16 Jan 2005, Jim Lux wrote:
> > Is it worth cooling down the room to a Class A Computer room standard or
> > save the money for hardware upgrade after three years? In warm countries
> > keeping 18ºC the air inside a room (PC-heated) when outside temperature
> > is 30ºC average it becomes pretty expensive to pay electricity bills. It
> > is cheaper to "circulate" 30ºC air and have from 40-50ºC inside the
> Fascinating system design question....
we had some 1Us where the clients put it in a harsh 99%
- 150F is the ambient operating ( normal ) temp and running 24x7
- the ide disks ( basically all ) died within 1yr
( cpu/mem/ps all seems fine )
= circulating hot air will not help
= - cooler air needs to come in and hot air must go out
> Such data is very hard to come by, however, a good rule of thumb is that
> life (MTBF) is halved for every 10 degree (C) temperature rise (Arrhenius
where the degradation starts from say 25C or 20C .. wherever they spec'd
the mtbf starting point
> I have seen temperature vs MTBF data for disk drives, a google
> or search of a site such as Seagates should find it.
those mtbf, some disks are spec'd at a ridulous 1,000,000 mtbf hrs
> Of course, they do
> accelerated life testing at elevated temperatures, so there must be some
> analysis that equates X hours of operation at temperature Y to Z house of
> operation at temperature Y-30. The real question would be what's the life
> limiting component... I'd be willing to gamble (based on personal experience
> with PC failures over the last 20 years) that it's some component in the
> power supply.
i'd put my $$ on the "cheap" fans dying first
- adding better quality and redundant fans seems to work for 1Us
in regular operating environment
> > Links to this information are highly appreciated!
> > I remember old (40MB RLL disks shipping this information with the
> > device, several pages of printed manual) hardware showing the
> > difference in MTBF vs environment conditions, but nowadays commodity
> > harware does not consider this on the sticker on the top of the device...
> But it is available at mfr's websites, at least for some components.
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