These days, everyone is trying to be green and conserve power. I’m aware that running a bunch of computers 24/7 isn’t easy on the electrical bill, so I was interested in the low power aspect of the TS-439. I used the Kill-A-Watt meter from P3 to test the devices in my server closet. As advertised, the NAS draws 50 Watts during normal operation. If it is not accessed and spins down the drives, it will draw only 25 Watts. For comparison, my Linux Core 2 Quad draws 75 Watts when running Bit Torrent and more that 110 Watts when transcoding video.
Getting your NAS to spin down may be difficult, though. At first I had a hard time. However, after a bit of experimentation, I can say that the NAS does spin down when it is idle. In order to be idle, the drives may not be accessed. This means, that you cannot be accessing the NAS at all. Any Mac or Windows machines awake on your subnet will not allow the NAS to spin down. This is due to the fact that both Mac and Windows machines poll the NAS to see what shares are available, which keeps the NAS up.
Though mounted Linux machines shouldn’t keep the NAS busy since NFS does not poll or otherwise use the network if you’re not accessing the filesystem. This is unless you have a file browser pointed at the mounted shares; to be safe, close any windows showing files on the NAS and any programs that are accessing files on the NAS. The NAS also will not spin down if it is running the Download Station services or if the Twonky Media Server is rescanning content directories. I set Twonky to rescan directories every two hours so that it doesn’t keep the NAS up too much.
All in all, there is a good compromise between keeping your media server up to date and accessing your data that allow the NAS to spin down most of the time and save power.