So if we now know, (and we have seen similarly spirious behaviour with SATA Raid arrays), isn't the real solution to lose the node discs?
Regards Robin > >>> How did they look for predictive models on the SMART data? It sounds >>> like they did a fairly linear data decomposition, looking for first >>> order correlations. Did they try to e.g. build a neural network on it, >>> or use fully multivariate methods (ordinary stats can handle it up to >>> 5-10 variables). >>> >>> This is really an extension of David's questions below. It would be >>> very interesting to add variables to the problem (if possible) until >>> the >>> observed correlations resolve (in sufficiently high dimensionality) >>> into >>> something significantly predictive. That would be VERY useful. >>> >> >> RGB, good idea, apply clustering/GA/MOGA analisys techniques to all of >> this data. Now the question is, will we ever get access to this data? >> ;) > > As mentioned in an earlier e-mail (I think) there were 4 SMART variables > whose values were strongly correlated with failure, and another 4-6 that > were weakly correlated with failure. However, of all the disks that > failed, less than half (around 45%) had ANY of the "strong" signals and > another 25% had some of the "weak" signals. This means that over a > third of disks that failed gave no appreciable warning. Therefore even > combining the variables would give no better than a 70% chance of > predicting failure. > > To make things worse, many of the "weak" signals were found on a > significant number of disks. For example, among the disks that failed, > many had a large number of seek error; however, over 70% of disks in the > fleet -- failed and working -- had a large number of seek errors. > > About all I can say beyond what's in the paper is that we're aware of > the shortcomings of the existing work and possible paths forward. In > response, we are > <GOOGLE_NDA_BOT> > Hello, this is the Google NDA bot. In our massive trawling of the > Internet and other data sources, I have detected a possible violation of > the Google NDA. This has been corrected. We now return you to your > regularly scheduled e-mail. > [ Continue ] [ I'm Feeling Confidential ] > </GOOGLE_NDA_BOT> > > So that's our master plan. Just don't tell anyone. :) > -jdm > > P.S. Unfortunately, I doubt that we'll be willing or able to release the > raw data behind the disk drive study. > > Department of Computer Science, Duke University, Durham, NC 27708-0129 > Email: [EMAIL PROTECTED] > Web: http://www.cs.duke.edu/~justin/ > _______________________________________________ > Beowulf mailing list, Beowulf@beowulf.org > To change your subscription (digest mode or unsubscribe) visit > http://www.beowulf.org/mailman/listinfo/beowulf > Robin Harker Workstations UK Ltd DDI: 01494 787710 Tel: 01494 724498 _______________________________________________ Beowulf mailing list, Beowulf@beowulf.org To change your subscription (digest mode or unsubscribe) visit http://www.beowulf.org/mailman/listinfo/beowulf
