This is the one to look at once you're past eight bays or the array's busy all day, because WD rates it for 550 TB a year and doesn't care how big the box is. WD backs it for five years, which is a long time in drive terms. Recording is CMR, the right kind for RAID and ZFS.
!Watch out for
It's a 7,200 rpm drive and you'll hear it working.
Backblaze doesn't run enough of these for a failure rate we'd publish. On paper it makes 25 dB at idle and 32 dB seeking. WD lists 3.6 W at idle and 6 W working, which comes to 32 kWh a year for a drive that idles around the clock. Four of them in SHR or RAID 5 give 78 TB usable, or 70.9 TB once Windows has done its binary maths on it.
Specifications
Each value links to the Western Digital page or datasheet it came from.