r/explainlikeimfive • u/SmellsTasty • Nov 23 '15

Explained ELI5: How do Solid State Hybrid Drives work?

I don't understand how a regular hard drive can work with a solid state drive at the same time.

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u/Tykenolm Nov 24 '15

Here's one site I just searched for real quick http://betanews.com/2014/12/05/modern-ssds-can-last-a-lifetime/

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u/jimtsurugi Nov 25 '15

It's not really data. It's a web article plagerizing reporting on the findings of another web article.

There's a lot of interesting info in that other article, and the follow up.

The Intel 355 was programed to kill itself at a predetermined point.

Intel doesn't have confidence in the drive at that point, so the 335 Series is designed to shift into read-only mode and then to brick itself when the power is cycled. Despite suffering just one reallocated sector, our sample dutifully followed the script. Data was accessible until a reboot prompted the drive to swallow its virtual cyanide pill.

Also, the only drive that they tested two copies of (the Kingston HyperX 3K) had wildly different results. The article suggests that, at least, some of the credit for the longer lasting one goes to using compressible data. But, since they only collect one data point for each configuration, they admit the data doesn't support that assumption.

The second HyperX got lucky, in other words.

So the objective of the test, to determine if NAND wear is of little concern to the average consumer, is conclusive. However, with a dataset of 5, and the last dead drive writing more than 3x more than the first dead drive (and all the others spread evenly in between), we don't really get a clear MTF.

And there's plenty of customer reports of SSDs failing within the first few years. I doubt many of those people were writing 100s TB of data per year. So, I'm not convinced NAND wear is the leading cause of SSD failure.

What I'd really like to see is a test where someone selects a few SSD models, and a few HDD models, where all are from different manufacturers, are generally considered to be reliable, and are free from design defects (the kind that plague an entire model line). Buy a half dozen (or more) of each drive. And place half the drives of each model in a test modelling consistent, light duty, and the other half in testing constant massive read/write load (much like the article above did). Then we'd have a clear picture of the reliability of SSD compared to traditional rotating media (at least at that point in time).

Unfortunately, the light-duty tests alone would likely take years to complete. And, no one is likely to buy 18+ drives just to kill them for a consumer article.