Backblaze reveals HDD statistics for the second quarter of 2022
As of the end of the second quarter of this year, Backblaze was observing 219,444 HDDs and SSDs in the company’s data centers throughout the world. The analysis, 4,020 are used as boot drives, splitting between 2,558 SSDs and 1,462 HDDs. In their latest report, Backblaze focuses on the data drives under management — 215,424 to be exact — and reviews the quarterly and lifetime failure rates. The first part of their analysis reviews the lifetime failure rates of HDDs. Backblaze removed 413 HDDs from the observation. The exclusion is because those drives were utilized for testing or were in drive models that did not maintain up to 60 drives. The hard drives will be split into twenty-seven HDD models, with a total of 215,011 HDDs analyzed for the report. Some observations that Backblaze notes in their study is that the “lifetime annualized failure rate for all the drives listed above is 1.39%. That is the same as last quarter and down from 1.45% one year ago (6/30/2021).” They found that the annualized failure rate noted that three specific drives had the highest failure rate among the twenty-seven tested.
The 8TB HGST (model: HUH728080ALE604) at 6.26%. The Seagate 14TB (model: ST14000NM0138) at 4.86%. The Toshiba 16TB (model: MG08ACA16TA at 3.57%.
The three stand out from the remainder of the drives analyzed because the sample sizes were limited compared to others. The rates meant that the low and high confidence interval values were extensive and that the three drives were less reliable for the analysis. In the below chart, Backblaze has removed HDDs with what they consider “wide confidence intervals” and has only listed drives that were readily accessible to all customers. The following table lists the full results of the analysis, along with notable points.
The 6TB Seagate HDD drives (model: ST6000DX000) finally had a failure this quarter—actually, two losses. Given that this is our fleet’s oldest drive model with an average age of 86.7 months of service, a failure or two is expected. Still, this was the first failure by this drive model since Q3 of last year. We hope these drives to be cycled out in the future, but with their lifetime AFR at just 0.87%, they are not first in line. Our collection’s next oldest drive cohort, the 4TB Toshiba drives (MD04ABA400V) at 85.3 months, had zero failures for Q2. The last failure was recorded a year ago in Q2 2021. Their lifetime AFR is just 0.79%, although their lifetime confidence interval gap is 1.3%, which we’ve seen means we lack enough data to be truly confident of the AFR number. Still, they could last another 97 years at one failure per year—probably not. Three other drives had zero failures this quarter: the 8TB HGST (model: HUH728080ALE604), the 14TB Toshiba (model: MG07ACA14TEY), and the 16TB Toshiba (model: MG08ACA16TA). As with the 4TB Toshiba noted above, these drives have extensive confidence interval gaps driven by a limited number of data points. For example, the 16TB Toshiba had the most drive days—32,064—of any of these drive models. We need at least 500,000 drive days in a quarter to get to a 95% confidence interval. Still, any of these drives may continue to post great numbers over the coming quarters. We’re just not 95% confident yet. The 4TB Seagate drives (ST4000DM000) show their average age at 80.3 months. They have served us well, but they appear tired after nearly seven years of constant spinning. Their quarterly failure rate has increased each of the last four quarters to 3.42% this quarter. We have deployed our drive cloning program for these drives as part of our data durability program, and over the next several months, we will cycle these drives out. In Q2, the AFR increased to 1.46% for all drive models combined. It is up from 1.22% in Q1 2022 to 1.01% a year ago in Q2 2021. The aging 4TB Seagate drives are part of the increase, but the failure rates of both the Toshiba and HGST drives have also increased over the last year. It appears to be related to the aging of the entire drive fleet, and we expect this number to go down as older drives retire over the next year.
You can see more detailed descriptions in their report here.
