by Backblaze, a San Mateo, California-based backup and cloud storage company, shared data Thursday that gives us a unique insight into SSD reliability over up to four years of use. Looking at the 2,906 SSDs in its possession, the company tracked the failure rates of mostly consumer SSDs it was using as boot drives early in Q4 2018.
Backblaze has long shared data on hard disk drive (HDD) reliability, but this latest report offers a new perspective on HDD’s faster and more expensive cousins. As detailed in Backblaze’s blog post, the company uses SSDs to boot storage servers and to read, write, and delete logs and temporary files created by those storage servers. According to Backblaze, all SSDs analyzed have “similar” workloads.
Before we turn to Backblaze’s first table, which plots the annualized failure rates (AFRs) for 13 different SSD models, it’s important to note the limited sample size of 2,906 drives and the different number of drives for each model. Some drives were used much more actively than others, with active days ranging from 104 to 724,240 days. While these aren’t direct comparisons of SSD models, the chart provides a broad insight into SSD reliability that the average person can’t replicate themselves.
Backblaze’s blog provides several tables of SSD failure rates, but this one looks at AFRs over the entire period that Backblaze has used SSDs. The company started using SSDs in 2018, but has added most of the drives in the table below over the past three years.
The highest AFR (7.31 percent) comes from a 2 TB Seagate drive, but that drive has only been in use for 4,996 days. Looking at drives with at least 100,000 active days, the highest AFR comes from the single Crucial drive. But again, all of these drives have different drive counts and usage days.
Backblaze’s blog also highlighted the large confidence intervals in the table caused by the limited drive days for these SSDs.
“As we collect more data, these confidence intervals should become more accurate,” the blog states.
Backblaze said it prefers to analyze models with a confidence interval of 1 percent or less, which leaves us with two Seagate consumer drives, the ZA250CM10003 with an AFR of 0.66 percent and the ZA250CM10002 with an AFR of 0.96 percent. The data for the Dell drive (no failures) also meets Backblaze’s confidence interval standards, but the company says this is one of the few enterprise drives in its dataset, making it hard for consumers to come by. Dell’s VD boot-optimized storage solution is an M.2 drive mounted on a PCIe card for server deployments.
As you can see above, the drive with the highest AFR in 2022 was Seagate’s 250GB ZA250CM10002 at 1.98 percent. The SSD model had one of the most drive days and is the second most common SSD in Backblaze’s inventory at 554 drives.
Seven SSDs in the table above experienced zero failures in 2022. However, Backblaze noted that six of these only had 10,000 drive days, so “there isn’t enough data to make a reliable prediction about the failure rates of these drive models.”
Aside from the Dell, which consumers would be hard pressed to find, Crucial’s stats for the Seagate BarraCuda 120 SSD ZA250CM10003 and BarraCuda SSD ZA250CM10002 and the CT250MX500SSD1 are the most helpful, as they show at least 100,000 active days. Among these drives, the Seagate ZA250CM10003 had the lowest AFR at 0.73 percent.
Taking a step back, Backblaze also shared dates for 2020, 2021, and 2022 for its SSDs, including four models Backblaze added last year.
You may notice a high AFR on the Crucial 250GB CT250MX500SSD1, but note that Backblaze only added the drive in 2021 and it “recovered well in 2022 after some early failures in 2021,” according to Backblaze, which reported this trend expected to continue. The early failures of Crucial SSDs coincide with the bathtub curve, which assumes device failures occur early in the release cycle before falling to a stable rate and then increasing as the product ages.
Backblaze also highlighted different AFRs of Seagate ZA250CM10003 250GB and Seagate ZA250CM10002 250GB.
“The Seagate drive (model: ZA250CM10003) has delivered an AFR of less than 1% over all three years. While the AFR for Seagate’s hard drive (model: ZA250CM10002) slipped to almost 2% in 2022. The ZA250CM10003 model is the newer model of the two by about a year. Otherwise there is little difference, except that the ZA250CM10003 uses less idle power, 116mW versus 185mW for the ZA250CM10002. It will be interesting to see how the younger model fares over the next year,” the blog said.
Backblaze has previously demonstrated the reliability of SSDs versus HDDs over a five-year period, but this latest data gives us a model-by-model breakdown of the AFRs of SSDs in its arsenal over a slightly longer period. The longer Backblaze has these SSDs and puts them through their paces, the more insight into SSD reliability it can provide.
Backblaze’s full dataset is available on the Hard Drive Test Data page.
