Backblaze has published statistics on HDD reliability for 2018

More than five years ago, Backblaze published the first report on the use of disk drives in its servers. Backblaze provides a cheap cloud backup service. Their infrastructure is based on consumer-grade hard drives. The company has collected a large statistics on the resiliency of different types of HDD. Backblaze's fleet of drives at that time consisted mainly of Seagate, Hitachi and WD drives, and Hitachi drives were the most reliable.

Since then, Backblaze publishes statistics annually, and now it’s time for another report .

As of December 31, 2018, the company had 106,919 active HDDs, of which 1,965 boot disks and 104,954 data disks. The review shows the failure rates of hard drives with data in the company's data centers. It also discusses new HDD models that have been added to server racks throughout 2018, including the 12 TB model HGST and the 14 TB Toshiba model. It is clear that a lot of statistics have not yet been collected on new models, because they have only recently been installed and the number is small. So, it is still too early to finally bury, for example, the Toshiba MG07ACA14TA model with a bounce rate of 3.03% (if we bring it to annualized estimates). Maybe just got a bad game.

The table lists only those models for which statistics is collected from at least 45 copies (some of these drives were used just for testing). The number 45 is the minimum amount needed to fill one Backblaze Storage Pod in the data center. Thus, out of 104,954 hard drives, 104,778 pieces were left to analyze the statistics.


Note: the annual failure rate of 0.00% means that during 2018 there was not a single failure

Backblaze experts admit that by the end of 2018, the overall annual failure rate (AFR) was very good: only 1.25%. For comparison, in 2013 the numbers were much worse, and some Seagate models then fell down to AFR 25.4% (model Seagate Barracuda 7200, ST31500341AS). The second and third years of operation became especially critical for Seagate drives.


Statistics from the first Backblaze report for 2013

Now all models have shown themselves to be very reliable drives. Exceptions are cases when there were a small number of copies of a particular model (less than 500) and / or they all worked together for a small number of days (less than 50,000). In these cases, AFR cannot be considered reliable for making purchasing decisions.

The total AFR for all models for the year was only 1.25%, which is significantly lower than in previous years.

Backblaze writes that in 2018, replacing old drives with 2, 3 and 4 TB with drives of 8, 10, 12 became a noticeable trend, and in the fourth quarter - another with 14 TB. It can be assumed that this trend is characteristic not only for Backblaze, but also for the entire consumer market: many users made such an upgrade last year. In 2018, the total storage capacity of Backblaze increased from 500 to more than 750 petabytes, with an average of 75 disks added per day.

After last year's upgrades, there are almost no Western Digital disks left in the storage, only 383 of them are now working, all on 6 TB, this is only 0.37% of the total number of drives.

Backblaze notes good HGST discs (model HUH721212ALN604). In the first month of testing 1,200 such drives, only one failure was registered, so the company decided to increase their fleet. But the most popular disk in the data center was the Seagate 12 TB model (ST12000NM0007), which employs 29.7% of the farm.

The following table compares AFR by year and shows how much more reliable the discs became in 2018: the number of failures has been systematically decreasing for the third year in a row.



Another interesting observation: none of Toshiba’s 45 5 TB drives failed since the second quarter of 2016 (model MD04ABA500V). Also, the reliability of Seagate's 10 TB drives (model ST10000NM0086) with AFR is only 0.33% last year, with a total of about 1,220 disks that have worked out for 500,000 days, so the statistics are quite reliable.

Finally, the last table shows the failures of hard drives for all time since April 2013 - for those models that are still in operation.



The full data set of this review is published here . If you only need tables from this article, you can download a CSV file with data.