Disk Spin Down power management settings

PapaBear wrote:
Maxblack - even more expensive is the replacement tubes and the union electricians wages to come and change them out periodically. In a large industrial plant setting that drives many more decisions than the cost of anything else.

Not sure what implication you are drawing. however it is true that the cost of "relamping" is what is balanced against the cost of energy use. The US government advice says that if you won't be using the fluorescent lights for 15 minutes you should turn them off. (http://www.energysavers.gov/your_home/l ... opic=12280).

Anyway, our facilities have corridor lights on timers, and a couple years ago replaced the switches with motion-sensor versions that automatically turn off the lights in the offices if no motion has been detected for a while. So at least in our company there is no debate on turning off the lights.

The corresponding tradeoff for a NAS is balancing the power savings against the disk replacement costs. I haven't seen much definitive on this topic, though there are several researchers who have been looking at variations of Raid that allow some disks to spin down. For instance, concentrating frequently accessed data onto some of the disks can allow the other disks to spin down. One paper on this is here: http://www.eng.auburn.edu/~xqin/pubs/icpp10.pdf It is a bit surprising that there is so little information on what is suitable spin down threshold.