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Some Sold State Disks (SSD) have a mean time between failures (MTBF) of 2,500,000 hours. If you divide that by the rough number of hours in a year you get 2500000÷(365×24) ~= 285 years before there is a problem.

I know that the first generation SSD's used to have a short life - but now the estimated time before they fail seems absurdly high. Most warranties only cover them for 1-3 years it seems.

How long are the modern, SATA III drives supposed to last?

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closed as not constructive by DragonLord, Indrek, Nifle, Diogo, sblair Aug 22 '12 at 1:08

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Call me in 285 years and i will have an answer.... –  Moab Aug 21 '12 at 19:59
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Which are you going to believe? The marketing BS of 285 years, or the warranty period? –  BBlake Aug 21 '12 at 20:10
    
+1 for warranty period. That's how I judge every product's life expectancy... –  Tanner Aug 21 '12 at 20:24
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2,500,000 hours? [citation needed] –  Daniel Beck Aug 21 '12 at 20:42
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related: What happens when an SSD wears out? –  sblair Aug 22 '12 at 1:13

3 Answers 3

up vote 20 down vote accepted

You are misunderstanding MTBF.

What MTBF means is that if you have a large number n of drives running at the same time, you can expect to see a failure once every MTBF / n time units.

Basically, it measures how frequently relatively young drives fail; it does not say anything about the long-term survival of particular drives. These would be equivalent only if failures are linear over time, but obviously they are not. The failure rate generally increases over time.

Consider humans. Suppose that around age 20, 0.1% of males die each year. That would produce an MTBF of about 1000 years. This MTBF can be used, for example, by the military to predict the number of male non-combat deaths per year. But clearly it doesn't imply that people live for 1020 years! Mortality increases with age, so that inference would be spurious.

For more information, see https://en.wikipedia.org/wiki/Survival_analysis.

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This should be the accepted answer as it is the only one that explains the misconception of what MTBF means. –  ghoppe Aug 22 '12 at 0:02

Asking whether SSDs would really last 285 years is like asking whether you can drive 20000 miles with your car tires, there are a multitude of possibilities:

  1. You decide to go drive through nails or police street spikes after 10 miles, your tires fail.

  2. You crash into a wall after 1000 miles, now your tires have become useless.

  3. You tires suddenly stop working after 10000 miles, you wonder if it has to do with the sun.

  4. You have made it to 20000 miles, congratulations.

  5. You have made it to 80000 miles, you have put your car on top of a car truck.

Do you know in advance when the tire will give up? I don't. What tire by the way? This one?

Consider maximizing the lifetime of your SSD instead! :)

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Beware, Solid State Disks based on Flash memory (which most if not all are) have a limitation on the number of writes that can be performed which means that over time as you continue to write to the device you will eventually reach the limit of your device and won't be able to write to it any more. There are two types of flash memory, MLC which is cheaper, more dense and lower number of write cycles and SLC which is more expensive but has a higher write limit. This is most likely why the drives have a one or three year warranty. The warranty may also not apply if you have performed "excessive" writes to the device.

Most SSD flash drives are engineered to distribute the writes across all of the flash memory in the device to ensure that one section doesn't "wear out" prematurely. They also have more capacity than the user is able to use to also extend the usable life of the drive.

I hope that this helps. The MTBF number you are looking at is so high because SSD drives have no moving parts which inherently makes them more reliable. That being said, all electronic equipment can be damaged due to power issues, ESD, internal circuit flaws, excessive heat, etc.

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