SSD Lifetimes
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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.
--Jeff Moden
RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.Change is inevitable... Change for the better is not.
Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally) -
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.
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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
RBAR is pronounced "ree-bar" and is a "Modenism" for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
________Stop thinking about what you want to do to a ROW... think, instead, of what you want to do to a COLUMN.Change is inevitable... Change for the better is not.
Helpful Links:
How to post code problems
How to Post Performance Problems
Create a Tally Function (fnTally) -
It seems those SSDs are performing much better, and I do know some people that have gotten multiple years in SQL Servers with SSDs. Not a representative sample by any means, but they are better than some I heard about 3-4 years ago that measured the tempdb SSD lifetime in months.
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