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KHB: Real-world disk failure rates: temperatureKHB: Real-world disk failure rates: temperaturePosted Jun 16, 2007 2:41 UTC (Sat) by giraffedata (subscriber, #1954)Parent article: KHB: Real-world disk failure rates: surprises, surprises, and more surprises About those temperature correlations: temperature of what, how do they know, and why did temperatures vary?
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KHB: Real-world disk failure rates: temperature Posted Jun 16, 2007 10:44 UTC (Sat) by vaurora (subscriber, #38407) [Link] Part of the SMART protocol included reading temperatures from sensors inside the disk. The record temperatures are of the inside of the disk enclosure. The temperatures vary according to the external temperature, air flow around and in the drive, and the waste heat generated by the drive itself.
KHB: Real-world disk failure rates: temperature Posted Jun 18, 2007 3:52 UTC (Mon) by giraffedata (subscriber, #1954) [Link] That puts the question of temperature/failure correlation in a whole different light. The correlation people expect has to do with the idea that if you put a disk drive in a hot environment, it will die sooner than if you put it in a cool environment.But my guess is that the outside temperature and air flow around the drives doesn't vary among Google's sample, so any temperature difference inside the drive is due to the design of the disk drive. IOW, the correlation shows that the designs that run cooler are also the ones that fail more. Considering that the engineers do design for and test for failure rates, i.e. the failure rate is the independent variable, I would not expect a drive that runs hotter to fail more. Engineers would have designed it to run that hot. But I might be convinced that in their struggle to make a drive consume less power, and thus run cooler, the engineers sacrificed longevity. (I don't know enough about disk drive design to know how such a tradeoff would be made, but I'm sure there's a way). That could explain the negative correlation.
KHB: Real-world disk failure rates: temperature Posted Jun 20, 2007 2:09 UTC (Wed) by mhelsley (subscriber, #11324) [Link] Considering the energy needed to manufacture the hard drives and their lower lifetimes I wonder it truly results in net energy savings.
KHB: Real-world disk failure rates: temperature Posted Jun 20, 2007 16:40 UTC (Wed) by giraffedata (subscriber, #1954) [Link] Considering the energy needed to manufacture the hard drives and their lower lifetimes I wonder if it truly results in net energy savings. That's an insightful question, but as the true goal is to save resources in general, and not just energy (or fossil fuels and clean and clear air), the right question is actually a little simpler: Does the money a data center saves on electricity make up for the cost of more frequent replacements? The amount energy used in manfuacturing a drive is reflected in its price. Of course, we're only speculating at this point that there is any correlation between energy efficiency and failure rate. The one really useful result of these two studies is that manufacturers don't know what their drive lifetimes are, so users have been making buying decisions based on wrong numbers.
KHB: Real-world disk failure rates: temperature Posted Jun 19, 2007 23:21 UTC (Tue) by peterc (subscriber, #1605) [Link] Note also that those temperature sensors are not calibrated. I wouldn't be surprised if they have a design variability of 10%!
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