Re: RAID Class Drives`

[Bill Davidsen <davidsen@tmr.com>]

Joachim Otahal wrote:
> John Robinson schrieb:
>> On 18/03/2010 16:45, Joachim Otahal wrote:
>>> [...]  You should take care of the temperature of the drives,
>>> 30°C to 35°C is preferred, above 35°C the lifespan goes down, over 
>>> 40°C rapidly down.
>>
>> Do you have a reference for this? Most drives' operating temperature 
>> range is specified up to 55°C, sometimes higher for enterprise 
>> drives, without any indication (apart from common sense perhaps) that 
>> running them this hot reduces lifespan.
>>
>> Cheers,
>>
>> John.
>>
> About a half year ago the german publisher c't did this testing (or 
> reported from a big testing, cannot remember) what the best 
> temperature of desktop drives is. The statistic varied from drive to 
> drive since some are less than 5°C over room temperature, others are 
> 15°C or more over room temperature (of course mounted behind a silent 
> fan which keeps the air moving, no turbine mode).
> The result was that 10°C and 15°C are not good for the drives. The 
> "perfect sweet spot" changes from drive to drive (even within on 
> manufacturer), but all of them had their sweet spot somewhere around 
> 20°C to to 35°C with variation in the range of measurement error.
> Some drives has a higher failure rate at 40°C, for some 55°C was no 
> problem at all and showed no real change in the failure rate. The last 
> two examples were the extreme cases.
>
> Some of my drives are 2°C above room temperature, others are 12°C over 
> room temperature. Sine I really take care that non reaches 40°C even 
> in summer the failure rate got down from "every few month" to once in 
> the 3 years which is the time I really take care of the drive 
> temperatures. There are 6 drives currently in use from 750GB (the 
> hottest of all my drives) up to 1.5 TB in my private machines, only 
> one of them shows a gradual change in the SMART values (reallocated 
> sector count), which mean it will probably fail in about 1.5 years if 
> the error rate stays constant. At work (at least the two machines 100% 
> under my control) I had the same effect, keep the HD's cool and they 
> will live long, let them get over 40°C and be ready to replace them soon.

40°C is a good target, readily available to people in the Arctic. It 
requires a lot of cooling to do it in normal climates where the ambient 
may be mid to high 40s. Fortunately my experience looks more like 
Google's, as long as you move enough air over the drive to avoid hot 
spots they seem to do well, hitting 43-46 much of the time. If I replace 
them because they're obsolete and working, they lasted long enough. 
Perhaps being "always on" is part of longevity, the ones I have on for 
5-6 years seldom fail, the desktop cycled daily maybe half that.

I do note that the WD drives run about 8°C cooler than Seagate. That's 
the "black" drive, I guess, the "green" drives would run cooler, based 
on power use. I will switch to them next build.

-- 
Bill Davidsen <davidsen@tmr.com>
  "We can't solve today's problems by using the same thinking we
   used in creating them." - Einstein


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