Deltaqueue just posted the prices and there is a $5.00 difference between the two. So you pay 4% more for 2.5% less annual failures. That sounds close enough to be worth paying more for less operational expense. Obviously, backblaze gets a better deal or they would be buying up the Hitachi drives instead.
The AFR is 2.3 percentage points less (0.9% vs 3.2%), which in this case means that a single unit of the inferior brand is 3.5 times more likely to die during a full year of use. I'd love to see their calculations that justifies buying non-Hitachi drives.
I think percentage points is the right metric here. Spending a lot of money to cut down the frequency of a rare occurrence doesn't make sense, even if you can cut it down by 100x.
I have experience with hundreds of T of data stores. My opinion is very high of Hitachi 1T and 3T Deskstars. The problem is that they are not generally available - there could be months when you just could not order them.
