Disclaimer: I work at Backblaze. > though they're less reliable, it's cheaper to buy more of them Exactly. Each month our buyers go out and get bids for more

Disclaimer: I work at Backblaze. > though they're less reliable, it's cheaper to buy more of them Exactly. Each month our buyers go out and get bids for more drives. The cost is input into a little spreadsheet, and the SPREADSHEET tells us which drive to buy. It isn't about picking the most reliable drive, we have a software layer and redundancy for that! It is about picking up the least expensive drive. The spreadsheet isn't complicated. If drive model X fails 1% less but costs 2% more then we don't buy it that month. It might change the next month. If you want to win our business, just look at the failure rates and under bid the competitors by the failure rate of your drive. There are some other things in the spreadsheet I should mention. If a drive is twice the density (let's say a 16 TByte drive vs an 8 TByte drive) it is still the same physical size and we pay for physical space rental in datacenters. And another thing is that drives that are twice as dense uses approximately the same amount of electricity, and power costs are an ENORMOUS amount of our overall cost of operation. So the spreadsheet will choose a more dense drive even if it is slightly more expensive per TByte just because of the other savings it implies. Again, the spreadsheet isn't complicated, but the spreadsheet tells us which drive to buy. If you are only going to purchase one drive, and you aren't going to back it up, you should sort by reliability of that drive. You are also insane -> always backup your drives!! And as long as your drive is backed up and you trust the backup, then who cares if the failure rate is 1% or 2%?