Backblaze - disk failure report
| TestsIn February, cloud backup and storage company Backblaze released its 2021 annual report on hard disk drive failure rates.
For the first time this year, Backblaze has published a special follow-up to its 2021 annual report on solid-state drives (SSDs).
Looking first at the standard HDD report, Backblaze ended 2021 with 203,928 HDDs under its wing.
Out of a total of 203,928 drives, Backblaze removed 409 drives from its statistics. These were for testing purposes or the company did not have at least 60 copies of a given drive in use. This brings the total to 202,759 hard drives. Of these, a total of 1,820 drives failed in 2021.
Backblaze measures the reliability index using an annual failure rate. AFR = (disk failures / (days of disk operation / 365)) * 100. Of the drives tested, the lowest failure rate was recorded for a 6TB Seagate drive (model ST6000DX000) - the annual failure rate (AFR) was only 0.11%.
Backblaze points out that this is extremely impressive, considering that the aforementioned model is the oldest in its fleet, with an average age of 80.4 months.
Two drives added in 2021 are performing particularly well. The 16TB WDC drive (model WUH721816ALE6LO), which has an average age of 5.06 months, has an AFR of 0.14%. Toshiba's 16TB drive group (model MG08ACA16TE) has an AFR of 0.91%.
The total AFR in 2021 for all Backblaze drive models was 1.01%, slightly higher than in 2020, when the AFR was 0.93%. However, 1.01% is significantly lower than the 2019 AFR of 1.89%. Overall, the best performers over the past three years have been HGST and WDC, whose AFR was below 0.5% in all but a few quarters. Toshiba came next, with Seagate drives boasting the highest AFR. Of course, when you dig deeper into the data, you'll find that there are drives from every manufacturer that perform well.
Let's now turn our attention to a new report on SSDs. While Backblaze uses HDDs for data storage, the SSDs in the report are used exclusively as boot drives. Starting in Q4 2018, Backblaze began replacing failed HDD boot drives with SSDs. With Backblaze, boot drives also store log files and temporary files produced by the storage server. Each day, the boot drive reads, writes and deletes files. By the end of 2021, Backblaze had 2,200 SSDs in use.
The annual failure rate of SSDs in general is similar to that of HDDs. In 2019, the AFR was 0.86%. In 2020, it was 0.78%. Last year, the rate rose slightly to 1.22%. In 2021, however, there are two notable exceptions. SSDs from Crucial (CT250MX500SSD1) and Seagate (ZA2000CM10002) failed at 43.22% and 28.81% respectively. Unlike the HDD report, there is a difference here in the size of the units tested. Backblaze used only 20 Crucial drives, and they were all installed in December. Although the AFR is high, we are dealing with a small number of test units.
In the case of the Seagate drive in question, the situation is even more extreme. There are only four such drives in use, and one of them has failed.
In general, not all SSD models are used in significantly large numbers. Backblaze had 1,090 Seagate ZA250CM10003 drives in use, and in 2021 their AFR was 1.04%. In addition, the company used 562 Seagate ZA250CM10002 drives. Their AFR was even more impressive at 0.36%. Of the 250 Dell DellBoss VD SSDs. None of them failed.
Also appearing in the data are two SSD models that are not included in the report, including the Samsung 850 EVO 1TB and the HP SSD S700 250GB. These were used for internal testing or specific migration tasks.
While 2,200 SSDs is a small number of drives, it's still a huge amount of data to analyze. Backblaze intends to keep adding SSD boot drives to its portfolio, improving data quality. It is also considering adding SSDs that Backblaze uses in other types of servers in its environment to its 2022 annual report.
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