“The 4 TB HGST drives have roughly 6000 hours on them after ten years.”
Twenty-four drives, ten years, zero failures and zero checksum errors. The machine is off most of the time: 6000 hours is about 250 days of runtime in a decade. The BMC alone draws 7 W at idle, so the whole box gets powered down, and the UPS went for burning 10 W by itself. The most reliable drive is the one that isn’t spinning.