NAS Disk Test - 3rd test extremely slow.

I've looked for studies on this topic, but the ones I've found are all from the mid-90s - and disks are very different now. So my opinion reflects my intuition more than anything else.

On the power side, your spin-down stats suggest that you'd save at most 70-75 kwh of electricity per year in direct power costs. That would save me about $20-$25. I'd take those savings if they are free, but they aren't enough for me to spend a lot of time trying to maximize them.

At +6 spin-ups per day, each drive spins up about 10,000 times over 5 years. It seems to me that the drives should last at least as long as drives running 24x7, given that you are also reducing the spinning hours over that timeframe by 15,000 hours. If the spin-ups exceeded the hours saved (e.g, 12 spin ups per day for 8 hours saved), I'd probably increase the threshold. But there's no engineering behind that, it just seems sensible to me.

EDIT- the 70-75 kwh power savings is an upper bound (real savings would be less). I based it on the difference between average power and standby power (4.5 - 4.1). It's probably more accurate to use the difference between idle power and standby power (3.3 - .04). If you do that, the power savings estimate drops to 50 kwh per year.