Konstantin Olchanski wrote: >>Does anyone have an actual formula? > > > I doubt it, because it requires measuring lifetimes, which takes > years, by which time the data are useless because the disks you used > are obsolete. I found this article on drive reliability from Seagate: http://www.digit-life.com/articles/storagereliability/ They do indeed model the temperature derating as an exponential, such that 25C is the reference temp and at 30C the MTBF is reduced to 78%. Running the drive at 40C gives you half the lifetime. Can't find anything about spinup/down though, but they do talk about how MTBF depends on power-on hours per year, which should be a correlated quantity. They assume the MTBF goes *up* the fewer POH/yr the drive has, there's never any reduction due to excessive spinup/down, or at least the reduction is never dominant. They also talk about the effect of duty cycle. cheers, /Patrik
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