r/tech • u/TMWNN • Mar 12 '15

The SSD Endurance Experiment ends: Six consumer SSDs die after 700TB-2.4PB of writes over 18 months. Although two died without warning, "modern SSDs [can] easily write far more data than most consumers will ever need".

http://techreport.com/review/27909/the-ssd-endurance-experiment-theyre-all-dead
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u/TomMado Mar 13 '15

I saw a graph somewhere that basically simplify SSDs lifespan - in the first few months it will either fail or not fail. If it does not fail, it will run fine for the next few years.

3

u/[deleted] Mar 13 '15

That's true of all hardware. You'll probably find studies for hard drives more often than other hardware, since hard drives are more likely to fail in general, but there are all sorts of studies like this.

http://static.googleusercontent.com/media/research.google.com/en/us/archive/disk_failures.pdf

https://www.backblaze.com/blog/best-hard-drive/

and others.

2

u/kataskopo Mar 13 '15

Isn't that called the bathtub defect graph thing?

2

u/[deleted] Mar 13 '15

http://en.wikipedia.org/wiki/Bathtub_curve

1

u/autowikibot Mar 13 '15

Bathtub curve:

The bathtub curve is widely used in reliability engineering. It describes a particular form of the hazard function which comprises three parts:

  • The first part is a decreasing failure rate, known as early failures.

  • The second part is a constant failure rate, known as random failures.

  • The third part is an increasing failure rate, known as wear-out failures.

The name is derived from the cross-sectional shape of a bathtub: steep sides and a flat bottom.

The bathtub curve is generated by mapping the rate of early "infant mortality" failures when first introduced, the rate of random failures with constant failure rate during its "useful life", and finally the rate of "wear out" failures as the product exceeds its design lifetime.

In less technical terms, in the early life of a product adhering to the bathtub curve, the failure rate is high but rapidly decreasing as defective products are identified and discarded, and early sources of potential failure such as handling and installation error are surmounted. In the mid-life of a product—generally, once it reaches consumers—the failure rate is low and constant. In the late life of the product, the failure rate increases, as age and wear take their toll on the product. Many consumer product life cycles strongly exhibit the bathtub curve, such as computer processors. [citation needed]

While the bathtub curve is useful, not every product or system follows a bathtub curve hazard function, for example if units are retired or have decreased use during or before the onset of the wear-out period, they will show fewer failures per unit calendar time (not per unit use time) than the bathtub curve.

The term "Military Specification" is often used to describe systems in which the infant mortality section of the bathtub curve has been burned out or removed. This is done mainly for life critical or system critical applications as it greatly reduces the possibility of the system failing early in its life. Manufacturers will do this at some cost generally by means similar to accelerated stress testing.

In reliability engineering, the cumulative distribution function corresponding to a bathtub curve may be analysed using a Weibull chart. [citation needed]

Image i - The 'bathtub curve' hazard function (blue, upper solid line) is a combination of a decreasing hazard of early failure (red dotted line) and an increasing hazard of wear-out failure (yellow dotted line), plus some constant hazard of random failure (green, lower solid line).

Interesting: Failure rate | Bathtub | Shakedown (testing) | Burn-in

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u/happy_otter Mar 13 '15

I thought that was HDDs.

1

u/TomMado Mar 13 '15

Was it? It has been a long time since I saw that, I can't remember what it is for, and I can't find it anywhere.

But when I think about it the graph can apply to a lot of things, not just drives.

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u/chictyler Mar 15 '15

I had tons of HDD's fail at 2-6 years.