Michael Valentine Jones (11/26/2012)
Jeff Moden (11/26/2012)
Steve Jones - SSC Editor (11/26/2012)
Jeff Moden (11/26/2012)
Michael Valentine Jones (11/25/2012)
I think they quote most mechanical disks with a MTBF of 1 million+ hours. I have to assume that they get these numbers from the reported failure rate of large numbers of disks, but maybe they just make them up.
Yeah... I don't believe those numbers, either. 😛
They're statistical extrapolations. There's some science, but "mean" is "mean", not likely or expected. It means that half fail later, which implies that yours might fail tomorrow.
Precisely. I was in the service so I definitely know what MTBF stands for (Most Troubles Begin way more Frequently :-D)... especially the ones that claim a million + hours. 😛
If they have enough drives in service, MTBF should not be hard to calculate:
5,000 drives in service * 8,760 hours/year at 100% duty cycle = 43,800,000 total drive operating hours/year, so 43 failures/year would give you 1,000,000 MTBF
Of couse, there may be a big difference in the failure rate of new drives vs. 6 year old drives, and they probably don't have any history for that.
Let us (or is that "lettuce") hope they're not tossing the salad with those kinds of calculations. 🙂
Still, that wouldn't be so bad... it's a 0.86% failure rate.
--Jeff Moden
Change is inevitable... Change for the better is not.