"Each quarter, Backblaze updates our hard drive statistics with the latest data. As of the end of Q2 2015, there were 47,561 drives spinning in our datacenter. Subtracting out boot drives, drive models with less than 45 drives and drives in testing systems, we are publishing data on 46,038 hard drives spread across 21 different models, from 1.5TB to 8.0TB in size" - BackBlaze
Find out the results: https://www.backblaze.com/…/hard-drive-reliability-stats-f…/