Backblaze has recorded and saved daily hard drive statistics from the drives in their data centers and released the statistics for the year 2017. At the end of 2017 they had 93,240 spinning hard drives. Of that number, there were 1,935 boot drives and 91,305 data drives

Below are the lifetime hard drive failure statistics for the hard drive models that were operational at the end of Q4 2017. As with the quarterly results above, Backblaze have removed any non-production drives and any models that had fewer than 45 drives. First the Q4 results:

The disks of with a large number in use and that have dropout a percentages above two percent, are the Seagate ST12000NM0007 with a failure rate of 2.01 percent, the Western Digital WD60EFRX, with a failure rate of 3.66 percent and the Seagate ST4000DM000, with a failure rate of 2.89 percent.

The failure rate for each year is calculated for just that year. In looking at the results the following observations can be made:

• The failure rates for both of the 6 TB models, Seagate and WDC, have decreased over the years while the number of drives has stayed fairly consistent from year to year.
• While it looks like the failure rates for the 3 TB WDC drives have also decreased, you’ll notice that we migrated out nearly 1,000 of these WDC drives in 2017. While the remaining 180 WDC 3 TB drives are performing very well, decreasing the data set that dramatically makes trend analysis suspect.
• The Toshiba 5 TB model and the HGST 8 TB model had zero failures over the last year. That’s impressive, but with only 45 drives in use for each model, not statistically useful.
• The HGST/Hitachi 4 TB models delivered sub 1.0% failure rates for each of the three years. Amazing.

A Few More Numbers

To save you countless hours of looking, we’ve culled through the data to uncover the following tidbits regarding our ever changing hard drive farm.

• 116,833 — The number of hard drives for which we have data from April 2013 through the end of December 2017. Currently there are 91,305 drives (data drives) in operation. This means 25,528 drives have either failed or been removed from service due for some other reason — typically migration.
• 29,844 — The number of hard drives that were installed in 2017. This includes new drives, migrations, and failure replacements.
• 81.76 — The number of hard drives that were installed each day in 2017. This includes new drives, migrations, and failure replacements.
• 95,638 — The number of drives installed since we started keeping records in April 2013 through the end of December 2017.
• 55.41 — The average number of hard drives installed per day from April 2013 to the end of December 2017. The installations can be new drives, migration replacements, or failure replacements.
• 1,508 — The number of hard drives that were replaced as failed in 2017.
• 4.13 — The average number of hard drives that have failed each day in 2017.
• 6,795 — The number of hard drives that have failed from April 2013 until the end of December 2017.
• 3.94 — The average number of hard drives that have failed each day from April 2013 until the end of December 2017.

Backblaze Hard Drive Stats for 2017 - HGST HDDs Very Reliable