Turning the calendar from April's picture of a tabby kitten with a yarn ball to May's photo of two calico kittens curled up inside coffee mugs means we are one-third of the way through 2018. It also means that Backblaze is back with its latest hard drive reliability report. The cloud backup outfit provides data about the reliability of drives in its enormous storage pool every three months, and the results this quarter are the best so far.
At the end of the quarter, Backblaze pooled together reliability data from 98,046 drives that met the criteria for inclusion. Long-time readers will know that Backblaze tends to use more drives from Seagate than from other manufacturers, and that trend continues this quarter—just four Seagate models represent over 73% of all drives in the report. Furthermore, all of Backblaze's drives with capacities larger than 8 TB come from manufacturer. All told, the company tracked data from fifteen models from Hitachi, Seagate, Toshiba, and Western Digital.
The annualized failure rate for Q1 2018 fell to just 1.2%, down from 1.65% in the previous quarter. Seagate's 4-TB ST4000DM000 had the highest single-model annualized failure rate at 2.3%, with WD's 3 TB WD30EFRX following closely at 2.25%. Those two models are some of the smallest-capacity models that Backblaze keeps in operation, suggesting they may also be among the oldest.
When looking at reliability over the hard drives' lifetime, the annualized failure rate across all manufacturers rises to 1.84%. The big losers in this metric are a pair of WD drives, the 3-TB WD30EFRX mentioned above and the company's 6 TB WD60EFRX model. We must note that Backblaze ran fewer than 450 of each of those models, a small sample size compared to the pool of nearly 31,000 Seagate 4 TB drives. That 1.84% annualized failure rate is the lowest the company has ever seen, beating the previous best of 2% in the previous quarter.
Backblaze has found exceptionally low failure rates for Toshiba drives over the last couple of quarters and is introducing 8-TB models from the manufacturer into its pool. The 20 units in use aren't enough for inclusion in the company's reliability report, but the company did point out that those drives have been flawless so far. Backblaze also notes the number of helium-filled drives from Hitachi and Seagate is growing and teased comparisons of helium-filled and standard drives in the future.
Gerbils that want to take a closer look at the company's figure can download Backblaze's data in raw form here or read the Q1 2018 writeup by following this link. Those that choose to pore over the numbers themselves might notice that the company has started recording five new SMART attributes, all of which are related to SSDs. Backblaze experimented with speeding boot times of its servers with Samsung 850 EVO SSDs before deciding the improvements weren't worth the extra cost.