Cloud backup provider Backblaze has released its hard drive reliability statistics for the third quarter of 2019.
The company compared active hard drives used in its operations from Seagate, Western Digital, Toshiba, and HGST to compile the report.
As of September 30, 2019, Backblaze had 115,151 spinning hard drives, comprising 2,098 boot drives and 113,053 data drives.
Reliability was measured as an annualised failure rate, calculated using the number of drive failures relative to the number of active drive days for each disk.
Backblaze recorded the number of failures for each hard drive from 1 July to 30 September 2019, extrapolating an annualised failure rate from this data.
Instead of publishing a quarterly perspective on failure rates, however, the company only provided lifetime statistics updated with its latest data set.
Blackblaze said that it would only reflect the lifetime failure rates this quarter due to the effect of one of its integrity checks on its quarterly data.
“For the Q3 table, the data which we typically use to create that report may have been indirectly affected by one of our utility programs which performs data integrity checks,” Backblaze said.
“While we don’t believe the long-term data is impacted, we felt you should know.”
Backblaze noted that drive failures only occur when disk sectors are accessed and found to have failed, meaning the process of conducting an integrity check would result in a reported increase in failures.
This does not mean that the drives are failing at a higher rate, only that activity conducted by Backblaze improved the probability of detecting them compared to previous quarters.
The company still published its lifetime failure rate data, which measures hard drive reliability from April 2013 – 30 September 2019.
Lifetime Failure Rates
|Model||Drive Count||Drive Failures||Annualised Failure Rate|
|4TB Hard Drives|
|6TB Hard Drives|
|8TB Hard Drives|
|10TB Hard Drives|
|12TB Hard Drives|
|14TB Hard Drives|