As of March 31, 2018, the company had 100,110 hard drives working for it, made up of 1,922 boot drives and 98,188 data drives, ranging from 3TB WDC WD30EFRX drives all the way up to 10TB and 12TB Seagate ST10000NM0086 and ST12000NM0007 drives, along with 10 Samsung 850 EVO SSDs.
The overall Annualised Failure Rate (AFR) for Q1 sat at just 1.2 percent, well below the Q4 2017 AFR of 1.65 percent. Some drives had an AFR of zero percent and did not fail at all while the 4TB Seagate ST4000DM000 had the highest AFR of 2.3 percent , out of 30,941 drives the company had in service, 178 failed during the Q1.
Backblaze has increased its use of HGST 8TB HUH728080ALE600 drives from 45 last quarter to 1,045 this quarter. This is because the 10TB and 12TB drives were more available and the price per terabyte of the 8TB drives had gone down. This "presented an opportunity to purchase the HGST drives at a price in line with our budget".