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Google Releases Paper on Disk Reliability
oski4410 writes "The Google engineers just published a paper on Failure Trends in a Large Disk Drive Population. Based on a study of 100,000 disk drives over 5 years they find some interesting stuff. To quote from the abstract: 'Our analysis identifies several parameters from the drive's self monitoring facility (SMART) that correlate highly with failures. Despite this high correlation, we conclude that models based on SMART parameters alone are unlikely to be useful for predicting individual drive failures. Surprisingly, we found that temperature and activity levels were much less correlated with drive failures than previously reported.'"
Excellent, i have been looking forward to thi *%)%*# DISK FAILURE
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I noticed this too. If a Google-sanctioned report had charts of which brands were more reliable, this would do serious damage to the brands that didn't perform so well. No wonder they sidestepped the whole issue!
FTA:However, in this paper, we do not show a
breakdown of drives per manufacturer, model, or vintage
due to the proprietary nature of these data.
But, of course.
What?
More likely: "We buy millions of dollars worth of drives each year, and our buying decisions are driven in part by the reliability data that we collect. If we told everyone what kind of drives work best, more people would buy those drives, driving up the price that we pay."
They would have released that data, but it was saved on a Maxtor.
You really didn't read the article, did you? On page 3 (Section 2.2 Deployment Details), the authors state: "More than one hundred thousand disk drives were used for all the results presented here. The disks are a combination of serial and parallel ATA consumer-grade hard disk drives, ranging in speed from 5400 to 7200 rpm, and in size from 80 to 400 GB. All units were put into production in or after 2001. [...] The data used for this study were collected between December 2005 and August 2006."
What are you waiting for Google to tell you? Are you really accusing them of being evil because they did a study, described their methodology, detailed their results, presented their analyses, and published it all for anyone who is interested?
You describe their conclusions as:
But there is no contradiction at all if you are smart enough to understand. They are telling you that if SMART identifies a problem with a drive then it is very likely that drive will fail within 60 days. But in a sample of 100,000 drives, many drives will also fail that have not returned errors on SMART scans. Thus SMART is a reliable indicator of impending failure but is not a silver bullet that can recognize and predict all failures before they happen.
Next time you have access to 100,000 hard drives, can analyze patterns of failure among them, can use those failures as a benchmark against which to measure analysis tools, and can come up with better recommendations for predicting failure than this study, then by all means let us know. But if you're looking for Microsoft or Western Digital or Seagate or Yahoo to perform and publish this kind of study for free, I think you may be waiting a good long while.
Another translation:
We're not so bloody stupid to believe that our competitors are standing in the aisle of Circuit City and scratching their head over whether to buy a Seagate or WD drive.
We know that our competitors all have their own metrics and their own relationships with manufacturers and frankly, we don't care. We know our competitors also measure these things, and we're not telling them anything they don't already know.
We aren't particularly worried about saying that some drives fail, because everyone who cares already knows that some drives fail. Everyone whose job it is to know which drives fail first already knows that as well.
But we're not going to tell you which brand fails at a higher rate than normal because we don't need a lawsuit that would cost us a lot of money but in the end would only confirm what the people who need to know these things already know.
We will, on the other hand, describe the tests we ran, our methodology, our results, and our analyses. We do this just for kicks and we hope you can learn something from the results.
And we hope you have a nice day.
Well, obviously you're not a lawyer :-) Otherwise you would know the answer.
What?
The paper claims "more than 100 thousand drives". But the nice thing is that you can derive the actual number from the error bars, for example those in figure 4. The data should be governed by Poisson statistics, which means that the standard deviation in the counts is equal to the square root of the count. However, their error bars seem to be about a factor 2 larger than the standard deviation, because normally around 68% of the data points should lie within one standard deviation from the "smooth curve". Let's assume the error bars are 95% confidence intervals, i.e. 2 standard deviations.
Look at the data for 20 to 21 C. It tells you that it represents a fraction 0.0135 of their total drive population, with an average failure rate of 7 +- 0.5 %. Following the reasoning above, this 7% should represent 784+-28 drives. Since these represent 7% of 1.35% of the total number of drives, we can derive that the total number of drives is 784/0.07/0.0135 = 830,000 drives. Trying the same thing for 30 to 31 C gives 826,000 drives, which seems fairly consistent.
So can we assume that Google has deployed 830,000 hard disk drives since 2001? How many servers do they have now?
Avantslash: low-bandwidth mobile slashdot.
One of largest retailers in Russia (and maybe in Europe - more than 300 terminals for orders in person at ex-factory building, busy 24/7) "Pro Sunrise" released information on failure rates of major components (CPU, Videocards, motherboards, IDE/SATA, etc) of PC they sold for Q1-Q2 of 2005.
8 3 - the article (in russian, but diagrams are self-explanatory).
http://pro.sunrise.ru/articletext.asp?reg=30&id=2
http://pro.sunrise.ru/docs/30/image001.gif - IDE/SATA (3.5" formfactor)
http://pro.sunrise.ru/docs/30/image002.gif - HDD (2.5" notebook formfactor)
In short, most returns are for Maxtor brand. Lowest - IBM/Hitachi.
Toshiba is worst in 2.5", and Seagate is best.
The chance to be blown are between 1/20 (Maxtor) to 1/70 (Hitachi).