Inspired by my read of this article http://sandeen.net/wordpress/computers/how-to-build-a-10w-6-5-terabyte-commodity-x86-linux-server/ I wanted to do some experimentation on my own NAS server.
The biggest power users (aside from the CPU) are the hard drives. In my NAS I have (5) 3TB WD Red Drives, and (1) 2TB WD Red Drive as well as a pair of Samsung 850 based SSDs. Of course the spinning disks consume the most power. I’m able to determine this based on the UPS which I have connected to the NAS. It has a nice little power meter built-in which I’m sure isn’t extremely accurate but is good enough for my needs.
After much experimentation with the options provided in the article above I found the only things to make a noticeable difference on my NAS were the spindowns of the mechanical harddrives.
Using the following script I was able to cut down my idle power draw from ~72 watts –> ~54 watts for an 18 watt savings or 25% which isn’t too bad!
#!/bin/bash echo "Setting Power down to 60 seconds." hdparm -S 12 /dev/sda hdparm -S 12 /dev/sdb hdparm -S 12 /dev/sdc hdparm -S 12 /dev/sde hdparm -S 12 /dev/sdf hdparm -S 12 /dev/sdd echo "Powering Down Hard drives immediately." hdparm -y /dev/sda hdparm -y /dev/sdb hdparm -y /dev/sdc hdparm -y /dev/sde hdparm -y /dev/sdf hdparm -y /dev/sdd