Today BackBlaze just released some new drive info. It’s handy, but ultimately proves my points – the data is a small data set (only 4500 drives) and comes three years after the drives are out of production. So while it is handy and interesting to know that Seagate had a higher failure rate three years ago, it does not give us usable information to change our buying patterns today. Nor does it show comparitives to other models and makers during that same window.

https://www.backblaze.com/blog/3tb-hard-drive-failure/

I have repeatedly published that data – it is discussed regularly. There is not an official publication from the investment bank where the study was done because banks do not do this, there is no financial reason to publish data for the IT industry by a bank. The reasons for this were covered in the article. Pretty much any company capable of doing such a study has no financial incentive to provide it to others, has legal barriers from doing so or would see the data as a competitive advantage not to be shared with their competition. Even in a case, like mine, where the data is benign and non-competitive, no company will voluntarily take on risk and cost of publishing a study that has no benefit to them.

I would be too glad to tell you what conclusions can be drawn from it.

The total number of drives is not the factor, it is the total number of different types of drives. 40,000 is not a large number when we are talking about a statistical sample set. If that were testing just four models, that’s an average of 10K drives of each. The numbers get much smaller very quickly. But the distribution is nowhere near even, a few models are in huge quantity and others are in very small. The total sample size is obviously misleading because 40K sounds good until you look at the distribution and individual samples.

Doing drive and array reliability requires very large numbers. For doing my own statistics I used over 32,000 drives at a time over 8 years, more than 60,000 drives total and I can assure you it was not statistically relevant at all with the rarity of drive and array failures. I could produce a few meaningful statistics about a single factor but did not have a sample size large enough to produce comparative numbers at all.

So while you draw the conclusion that a number like 40K is simply enough to be meaningful based on a raw number, I see 40K as unable to produce enough data to compare any meaningful number of options while overcoming background noise from the sample process. Stastically, when looking at very low failure rates and needing to not produce a single number but needing to compare many different models, types and options, 40K is far, far too small to tell us anything more than some very general numbers that we can only trust so far because the data is primarily about one or two specific models of drives and not about drives in general.

So I do no longer expect you to prove why their sample sizes should be too low.

I’ve used Green drives too with great results, but my pool is tiny and not statistically significant. Are you using them standalone or in storage pools (like RAID?) If the latter, look to WD Red drives instead. They are WD Green drives with modified firmware to be more reliable in that setting.

Could you please explain how you come to that conclusion?

I felt safe enough to decide my recent (small scale) buying decisions based on the published Blackblaze data.

My own experience had shown unsatisfactory reliability of WD green drives, but due to a much too small number that data is not representative.

For all those who do not have data from an installed base of a few thousand drives, imho Blackblaze gives valuable hints.

No doubt that every sufficiently big IT company nowdays collects this kind of data in order to minimize cost and/or risk.

But Blackblaze still is the only company to publish their findings in detail, because they believe that this kind of publicity gives them an advantage over their competition.

Not even Google published data about the manufacturers and models of their failure analysis!

And the big rest of companies is convinced that this kind of valuable know-how best suits their needs if it is not available to their competitors.

This is the short truth, no longer text is needed.