Monday, May 25, 2009

Home Server Energy Consumption

I'm moving toward 'less is more', where 'less' is measured in watts. Right now my entire home entertainment and technology stack uses about 150 watts total  (server + network + storage + Sun Rays + laptops + wall warts). I no longer use the stereo or television -  that stack is unplugged and consuming zero energy, and I don’t have any watt sucking game consoles. My next iteration of home entertainment & technology should use about 25 watts for all servers and storage and about 20 watts for each user end point (laptop). The server and network should be the only devices that run continuously. End points should suspend and resume quickly and reliably so that no more than one is normally running at a time, so the net of all server, network and user devices should be under 50 watts.

To get under my energy target, I’ve got to swap a 60 watt, 6 year old Sparc based SunBlade 150 with something that uses somewhere between 5 and 15 watts. Worst case energy-wise would be  netbook running Solaris, best case would be and ARM based micro server. A netbook running Solaris would use more power, but it would have more CPU and memory, ZFS, and a built in UPS. Storage would have to be USB powered notebook drives rather than 3.5” desktop drives. My total storage needs are under 250GB, so a pair of redundant USB powered notebook drives are adequate. (Transferring long term storage to DVD’s reduces its energy cost to zero, so as they fill up, I either delete or transfer.)
For user devices, low power laptops with generous use of power saving features should keep me near the 20 watt target. My XP and Vista computers don’t sleep or hibernate reliably so they tend to be running most of the time. Windows 7 and OSX sleep and hibernate reliably, so devices with those OS’s are set for maximum power savings even when plugged in. Switching the XP and Vista notebooks to W7 will allow me to use aggressive power saving settings and reduce their energy footprint.

Power measurements at my breaker box show about a 300 watt parasitic draw when there are no lights, refrigerators or other appliances running. I can account for 150 watts as computer related. Someday I’ll have to track down the other 150 watts.

As home lighting moves from 60 watts per device to 13 watts per device, so should home computing.
Inspired by this discussion.
…every geek seems to need to one-up those around them and somehow differentiate and prove their geekdom... this is done in one of two ways:
  1. More is More: These are the guys with a deep wallet that always have the fastest processors, biggest screens, flashy furniture, etc.
  2. Less is More: The geek who does the most with the least (and generally brags about it). The more obscure your setup the better.


  1. Don't forget the "desktop laptop," the Mac Mini. Apple claims that it draws 13 watts when idle (though if you load it up, it can pull up to 110 watts). It doesn't get you the built-in battery backup, though.

  2. That's a thought too, as would some form of micro sized ITX motherboard based system.

  3. I'm building a server with a micro ITX mobile atom motherboard and a pico-psu. It'll have 4 drives in it; 2x2.5" drives for the OS, and 2x3.5" WD green drives for media. I think I can get it under 30W... I'll let you know :) I'd still rather have an ARM server...

  4. I ended up buying a Mac Mini (server version) with two 500MB internal drives, mirrored, and an external 2.5" drive for time machine backups. It's about a 40w stack, including cable modem and Wifi.

    The only down side is that I had to join the (cargo) cult of the Mac, pay homage to Jobs the Savior, and tolerate a handful of partially implemented server side applications. :)