On Sun, Feb 05, 2006 at 03:42:26PM -0800, David Liontooth wrote: > In designing an archival system, we're trying to find data on when it > pays to power or spin the drives down versus keeping them running. > > Temperature obviously matters -- a linear approximation might look like this, > Lifetime = 60 - 12 [(t-40)/2.5] I would expect an exponential rather than linear formula (linear formula yelds negative life times). L = ... exp(-T) or L = ... exp(1/kT) > 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. > Or are different components stressed in a running drive versus one that > is spinning up, so it's not possible to translate the cost of one into > the currency of the other? I would expect that spinning-up a drive is very stressful and is likely to kill the drive [spindle motor power electronics]. In my experience disk die about evenly from 3 causes: no spinning (dead spindle motor power electronics), heads do not move (dead head motor power electronics), or spontaneusly developing bad sectors (disk platter contamination?). Hmm... NASA-type people may have data for life times of power electronics, at least the shape of the temperature dependance (linear or exp or ???). -- Konstantin Olchanski Data Acquisition Systems: The Bytes Must Flow! Email: olchansk-at-triumf-dot-ca Snail mail: 4004 Wesbrook Mall, TRIUMF, Vancouver, B.C., V6T 2A3, Canada - To unsubscribe from this list: send the line "unsubscribe linux-raid" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
